T he right t e m perature w o r l d w i d e

Transcription

1 T he right t e m perature w o r l d w i d e NEW with LAUDA TD 1 C and MPT C LAUDA Interfacial instrumentation: Tensiometer

2 Company h i s t o r y The d e v e l o p m e n t of LAUDA m easuring technology Dr. Rudolf Wobser founds the MESSGERÄTE- WERK LAUDA Dr. R. Wobser KG in the Baden town of Lauda. Computer controlled Tensiometer with automatic CMC determination (reverse CMC patented by LAUDA) Development of new types of laboratory thermostats in a modular system and development of cooling thermostats with machine cooling. As a result of the expanding of the range of products, the MESSGERÄTE-WERK LAUDA is renamed as LAUDA DR. R. WOBSER GMBH & CO. KG The first series-production thermostats produce a considerable growth in sales. Product introduction of first Drop Volume Tensiometer TVT 1 in the world for measuring dynamic surface and interfacial tension. At the same time, product introduction of the semi-automatic Ring/Plate Tensiometer TD 1 took place. Development of the first Bubble Pressure Tensiometer MPT 1 (see picture) in the world, using to the Fainerman/Miller method Introduction of the first Ring/Plate Tensiometer TE 1 and the Film Balance FW 1 (see picture) the first representatives of today s product group measuring instrumentation. Modular processor-controlled Viscosity Measuring system PVS with modern Windows software and the automatic Viscosity rinsing system VRM enters the market Market introduction of the first automatic Capillary Viscosity Measuring System in the world. Existing PVS/VRM complemented by fully automatic sampler becomes the VAS 1. The logical step to full automation of viscosity measuring. 2

3 I n t r o d uction Applications of tensiometry The improved Drop Volume Tensiometer TVT 2, equipped with the latest microprocessor technology and easy to use Windows program, was presented this year. A lot has changed since the company was founded in LAUDA has developed many technical refinements that have now become the standard. Emphasis used to be placed on technical innovation. Today, applications clearly define the focus of attention Introduction of the new generation of Ring/Plate Tensiometer TE 2 at ACHEMA Surface and interfacial measuring technology is used everywhere where surfactants are used, e.g. as wetting and spreading agents, emulsifiers, foam stabilizers, dispersants, lubricants, washing agents and waterproofing agents. Therefore, a tensiometer must be universally applicable The TE 3 with new highly sensitive measurement cell for the highest requirements and new features is developed: e.g. automatic surface cleaning and contact angle determination for fibres. The LAUDA measuring instrumentation for surfaces and interfaces provide valuable tools in research and development. They are useful in optimizing the wetting properties of coatings, for investigating the adsorption and diffusion of amphiphilic molecules and for the development of cleaners, washing agents and sprays that contain surfactants The new Ring/Plate Tensiometer TD 2 is presented at ACHEMA The handy equipment offers a comfortable control with large display. In the analytical laboratory, LAUDA measuring instrumentation is used to characterize emulsifiers and floatation additives, to investigate the dissolving behaviour of powders and tablets, and the adsorption behaviour of proteins and bio-surfactants. Another application area is quality control. LAUDA measuring instrumentation reliably monitors the surfactant content in aqueous solutions and cleaning agent residues in wastewater The new instruments MPT C and TD 1 C are examples for the new upcoming tensiometers which are independent from any PC. The easy use via remote control enables mobile, practicable and highly precise working. For physical reasons, tensiometers work optimally only in specific ranges. The area defined by the application is the deciding criteria. LAUDA has provided this brochure to help you to find the best instruments for your requirements. In addition: The informative presentation of the numerous application options and the technical data underline our claim of offering top technical performance at reasonable prices. 3

4 Overview Measured values Phases Methods Force methods Introduction TD 1 C Economical Ring/Plate Tensiometer with separate remote control and manual adjusting for beginners Surface tension Interfacial tension Density Weight Liquid/gaseous Liquid/liquid Liquid Du Noüy ring Wilhelmy plate Buoyancy method Weighing TD 2 Cost-effective Ring/Plate Tensiometer with separate remote control and automatic adjustment Surface tension Interfacial tension Density Weight Liquid/gaseous Liquid/liquid Liquid Du Noüy ring Wilhelmy plate Buoyancy method Weighing TE 3 Fully automatic Ring/Plate Tensiometer with numerous measuring options Surface tension Interfacial tension Critical micellar concentration Adsorption isotherms Contact angle on interfaces Density Liquid/gaseous Liquid/liquid Liquid/solid Liquid Du Noüy ring/ Wilhelmy plate Automatic surfactant feed Automatic dilution ( Reverse method) Dynamic Wilhelmy method Washburn method Buoyancy method Dynamic methods Introduction TVT 2 Robust Drop Volume Tensiometer for dynamic surface and interfacial tension testing Dynamic surface tension Dynamic interfacial tension Adsorption processes of emulsifiers Liquid/gaseous Liquid/liquid Drop volume method MPT C Bubble Pressure Tensiometer for surfactants in millisecond range Dynamic surface tension Surfactant monitoring Adsorption processes of surfactants Liquid/gaseous Bubble pressure method Recommended Thermostats Service Glossary

5 Ta b l e o f c o ntents Measuring range Dynamic time range Temperature range Application areas (examples) Control system Page 6 < 300 mn/m < 999 mn/m < 2 g/cm C For the testing of physical properties of liquids, solutions, development and testing of surface active substances Control with handy remote control Command 8 < 5000 mg < 300 mn/m < 999 mn/m < 2 g/cm 3 < 5000 mg 5 85 C Determination and testing of physical properties of liquids, solutions, waste water/waters; development and testing of surface active substances (surfactants, emulsifiers); surfactant content determination below CMC Control with handy remote control Command, RS 232 interface for data transfer to PC mn/m > 1 min C Determination and testing of physical properties of liquids, solutions, waste water/waters; development and testing of surface active substances (surfactants, emulsifiers), wetting properties of materials (hydrophobic/hydrophilic), contact angle and surface energies; surfactant content determination below CMC PC interface and control via Windows software 16 < 2 g/cm mn/m s 5 60/90 C For the development and selection of emulsifiers and other application optimized surfactants. Pure solvents; surfactant solutions, bio-polymers; quality control (water/ waste water control); Production monitoring in cosmetic industry, brewing, color or paint production, plant protection emulsions; biological liquids (e.g. eye fluids); highly viscous liquids PC interface and control via Windows software mn/m 0,001 2 s 5 85 C For the development and selection of fast surfactants to optimize of sprays, coating and printing processes, monitoring of surfactant-based aging and contamination; continuous control of surfactant production in reactors; monitoring and to optimize of washing processes; surfactant content determination above CMC Control with handy remote control Command, RS 232 interface for data transfer to PC 30 The right LAUDA thermostats available in various different technical configuration levels and with wide temperature ranges optimise the selection of applications

6 Force methods Surface and interfacial tensions are called static and quasistatic when their values, under constant external conditions, do not change, stop changing or change very slowly. They are therefore in or very close to thermodynamic equilibrium. To determine this, a ring (Du Noüy method) or plate (Wilhelmy method) is placed in contact with the surface of the liquid and the resulting force is measured. This force is a measure of the surface/interfacial tension. The geometry of the measuring body is set by standards, e.g. ASTM D971 and DIN The Wilhelmy m e t h o d Determination o f the surface and interfacial tension of liquids Measuring principle: The weight of the plate is tared. If necessary, calibration is performed F with a standard weight (100 mg ^= 24.5 mn/m). The plate is brought into contact with the sample liquid. The meniscus weight is then L d Air Contact angle α measured until the measurement values reach stability. The surface tension is calculated from the measured value. Condition: The contact angle α = 0 must be ensured through intensive cleaning, e. g. by thoroughly annealing the measuring body. Preferred a p p l i c ations: σ = F 2 (L+d) Static surface tension measuring Equipment suitable for this method: The LAUDA Tensiometer TD 1 C and TD 2 Examples o f t y p i cal s amples: (see p. 8 ff. and p. 12 ff.) Pure liquids, polar and non-polar liquids The fully automatic, PC controlled LAUDA Tensiometer TE 3 Low surfactant concentrations (see p. 16 ff.) Determination o f contact angle on solids Force Fr Fa Measuring principle: The contact angle and therefore the wettability of a solid can be determined from the known surface tension σ and measured weight of the liquid meniscus. The weight of the solid being measured is tared. The solid is brought into contact with the sample liquid and automatically moved up and down. The recording of force against distance results in a hysteresis force curve (see diagram). The F r and F a values determined are used to calculate the advancing angle (α a ) and the receding angle (α r ). 0 Immersion depth cos (α r,a ) = F r,a 2 (L+d) σ 6 Preferred a p p l i c ations: Determination of surface energy of solids Examples o f t y p i cal s amples: Foils/films Painted surfaces Silicone wafers Specially treated surfaces Equipment suitable for this method: The fully automatic, PC controlled LAUDA Tensiometer TE 3 (see p. 16 ff.)

7 F o r c e m e thods The Du Noüy ring method, rather than the plate method, is preferred despite greater effort (correction of measured value) as it gives triple the resolution. Further reason is simpler cleaning of the robust measuring body. The ring method offers particular advantages in fully automated measurements, e.g. the automatic determination of concentration dependencies (CMC) and in quality control. T he Du Noüy r i n g m e t h o d D e t e r m ination o f t h e surface and interfacial tension of liquids r F max Measuring principle: The weight of the ring is tared. If necessary, calibration is implemented with a standard weight (500 mg ^= 40.9 mn/m). The ring is dipped completely into the sample liquid. The ring is then slowly withdrawn from the liquid until maximum force is reached. The surface and interfacial tension are calculated from the maximum force F max. σ = F max 4πRf corr f corr: ring correction factor dependent on ring geometry and density ρ Ring m e asuring phases: Force without rupture Time P referred a p p l i c a t i o n s : Static surface and interfacial tension measurements Determination of CMC E x amples o f t y p i c a l s amples: Pure liquids, polar and non-polar liquids All types of surfactants and solutions Low surfactant concentrations Equipment s uitable for this method: The LAUDA Tensiometers TD 1 C and TD 2 (see p. 8 ff. and p. 12 ff.) The fully automatic, PC controlled LAUDA Tensiometer TE 3 (see p. 16 ff.) 7

8 LAUDA Ring/Plate Te n s i o meter T D 1 C E c o n o m i c a l i n t r o d u c t i o n i n t o t h e w o r l d o f t e n s i o m e t r y w i t h t h e L A U D A R i n g / P l a t e Te n s i o m e t e r T D1C.

9 A p p l i c a t i o n s TD 1C The TD 1 C units, whose technology has been completely revised and which bear a new design, offer even easier handling due to the handy remote control Command which has proven itself with LAUDA thermostats and measuring instruments. State-of-the-art processor technology allows extended documentation options. The measuring values are only displayed on the remote control. The evaluation of these values can be printed on an optional protocol printer. Easy determination of surface tension The measuring desk with the sample stage of the easy to handle tensiometer can be manually adjusted. The sample stage can be moved smoothly by means of ergonomic adjusting screws, like a microscope Easy measurements with Wilhelmy plate Simple determination of force maximum during the ring measurement By means of the high-resolution display of the remote Command control, the increase in wetting force during with drawing of the ring can be followed and the maximum force will be detected automatically and signalised by an acoustic signal without detaching the lamella The value displayed in the maximum is automatically corrected according to Zuidema and Waters, and thus corresponds to the surface tension of the measured liquid in nn/m At the touch of a button, the measured value and all parameters can be either saved or directly printed out on an optional protocol printer In total the TD 1 C is a very flexible and highly precise measuring instrument. Example: The perfect instrumentation for professional training At the university s practical training in physics students must learn to understand the principles in static surface and interfacial tension. This should be done with a simple instrument to learn the basics behind fully automated systems for tensiometry. S o l u t i o n : The robust and intuitive TD 1 C allows students to measure exactly and without additional corrections the static surface and interfacial tension of numerous liquids according to the standardized methods of Du Noüy and Wilhelmy. Furthermore, they are able to determine the density of liquid media according to the Archimedes principle. Now it is possible by a single, well-priced instrument to combine various experiments. Static surface tension [mn/m] Acceptable range Too much surfactant traces Current number of tests 9

10 LAUDA Ring/Plate Te n s i o meter T D 1C The TD 1 C model works with Du Noüy ring and Wilhelmy plate according to international standards (DIN 53914, ISO 304, ASTM D971). Furthermore, the density, according to the Archimedes principle, as well as smaller weights can be measured due to a newly-developed, even more powerful force-measuring cell with a considerably enlarged measuring range. Easy handling The measuring desk includes the high-resolution force-measuring cell and the lifting device for the manual positioning of the sample stage. Various standard test beakers with a diameter of up to 8 cm can be inserted into the large sample compartment accessible from all sides. The samples can be brought to the correct temperature by using a LAUDA RE 104 thermostat, for example, connected to a double-walled glass thermostating vessel. This handy, removable control unit enables the input of the measurement parameters and assumes the evaluation and representation of the measurement results. The large, high-resolution graphic display takes over the menu-driven user guide, and displays single measurements and results. The remote control with its self-explanatory menu-driven operation offers an optimum degree of user-friendliness. The scope of delivery: High resolution (± 0.1 mn/m, ± 1 mg) and enlarged measuring range up to 300 mn/m or 5 g Automatic maximum detection Automatic correction of measuring values (according to Zuidema and Waters) Semi-automatic calibration at three levels of precision with calibration weights Input of ring/plate dimensions possible Measuring desk with remote control Command and manual lifting device Other options: Print-out of the measuring values (surface / interfacial tension, density) on an optional printer at the touch of a key Storage of up to 500 measurements and the accompanying parameters Numerical sample description determined by the user Displaying of different measuring values and modes Measuring of the surface tension with Wilhelmy plate 10

11 A d v a n t a g e s a n d t e c h n i c a l d a t a T D 1C The measuring values displayed on the remote control Command, can be printed on an optional protocol printer. Double walled glass thermostating vessel Logging of measuring values Technical data TD 1 C Measurement type Surface and interfacial tension; density, weight Measurements surface and interfacial tension mn/m ring < 300; plate < 999 Resolution mn/m 0.1 Density measurement g/l < 2000 Resolution g/l 1 Weight measurement mg < 5000 Resolution mg 0.1 Calibration Calibration weight Sensitifity 3 levels Display 320 x 240 Graphic display Selection of measuring modes Menu-controlled Parameter input Menu-controlled Sample designation Numerical (0-999) Data storage Results Max. 500, with date, time and measuring parameters Stage movement (sample) manual Maximum recognition Automatic Ring correction Automatic according to Zuidema und Waters Documentation Protocol printers Weight kg approx. 5.0 Dimensions (WxDxH) mm 260 x 230 x 335 Power supply V; Hz External power adapter, V; 50/60 Hz Standard accessories Du Noüy ring Calibration weight Immersion plunger made from glass for determining density Further accessories Wilhelmy plate Double walled glass thermostating vessel Protocol printer Thermostats (see p. 40) Measuring technology standards DIN DIN ASTM D971 ISO 304 ISO

12 LAUDA Ring/Plate Te n s i o m e t e r T D 2 S u r f a c e a n d i n t e r f a c i a l t e n s i o n i n s t u d y a n d e d u c a t i o n a t t h e t o u c h o f a b u t t o n.

13 Applications TD 2 The LAUDA Tensiometer TD 2 is used to measure surface and interfacial tension, to determine the density of liquids and to measure small weights. The fully-automatic and cost-effective instrument consists of a precise electromagnetic weighing cell plus a remote control panel with a user-friendly graphic LCDscreen for precise measurements. Fully automatic yet simple and precise The TD 2 accomplishes the move to fully automated tensiometry and maximises user convenience directly over a PC. This extremely compact stand-alone device offers everything needed to measure surface and interfacial tension at the push of a button either in the laboratory or in the field as simply as possible. The accurate, reproducible results can be displayed, printed, saved, or transferred to a PC. With this device it is also possible to measure the density of liquids and to determine small weights. The convenient external control panel has a large graphic display that can be operated intuitively without special training. The integrated microprocessor handles sample positioning, force maximum detection and data correction. The program repeats measurements until a user-defined stability is reached and calculates static surface/interface tension and standard deviation over the last series of individual measurements, and compiles the results in easy-to-understand tabular format. Advantages of the Ring/Plate Tensiometer TD 2 The LAUDA Tensiometer TD 2 is easy to operate and supplies surface and interfacial tension of liquids at the touch of a button. It is therefore particularly suitable for beginners and for education. Surface and interfacial tension values are displayed digitally. The selection of measuring methods is simple and calibration is implemented using standard weights. Application options There are numerous applications for the LAUDA Tensiometer TD 2. It is used for example to determine and test physical properties of solutions, organic and inorganic liquids, liquid/liquid or liquid/solid dispersions, emulsions, etc. or to develop and test surface active substances such as surfactants and emulsifiers and to identify these such substances in effluents and in waters. Example: Control of cleaning water Surfactant traces left from cleaning agents can negatively affect foam formation, e.g. in beers, and must be prevented. A surfactant analysis would take too much time and would be too expensive. Solution: It can be determined whether traces of surfactant are present in the rinsing water by measuring the surface tension with the TD 2, e.g. using the ring method, and then comparing it with that of pure water. Static surface tension [mn/m] Acceptable range Too much surfactant traces Current number of tests 13

14 LAUDA Ring/Plate Tensiometer TD 2 With its robust design, ease of operation, and high precision, the TD 2 is ideal for use in all quality control applications. Since measurements are taken completely independently by the user and documented together with the required settings, the device also meets the stringent requirements of the GLP guidelines. The scope of delivery: High resolution (± 0.01 mn/m, ± 0.1 mg) and expanded measuring range up to 300 mn/m or 5 g Automatic maximum detection and maximum scanning with selectable range Tabular representation of individual measurements, number of measuring points, measuring time, corrected data (surface/ interfacial tension, density) Automatic ring correction (based on Zuidema and Waters) Automatic control of data stability based on predefined standard deviation Semiautomatic calibration in three accuracies with standard weights Input of ring/plate dimensions possible User-defined measuring point density and measuring time Other options: Storage of up to 500 measurements with related parameters Numerical user-defined sample designation Direct or subsequent output of data to optional protocol printer or PC (optional data transfer program required) via RS 232 interface Measurement and documentation of temperature in the sample by means of digital temperature probe (optional) Magnetic stirrer control for homogenisation of disperse samples Basic components: Measuring unit with high-reslution force-measuring cell and motor-driven sample platform Easy-operation control Remote Control Command This convenient remote control allows the complete remote operation of the measurement desk: (movement of sample table, input of measuring parameters, start of measurement, and transfer of data over RS 232-interface to printer or PC). This minimises vibrations to the measurement desk. The high-resolution graphic display offers menu-based user guidance and displays individual measurements and results in tabular format. Measurement desk The measurement desk is equipped with a high-resolution load cell and a DC motor for smooth movement of the measuring table with selectable speeds. A temperature sensor and magnetic stirrer can be connected to the device on request. The accessible sample chamber allows the use of sample beakers up to 8 cm in diameter. Table of surface tension measurements 14

15 Advantages and technical data TD 2 The TD 2 tensiometer uses the standardized Du Noüy und Wilhelmy measuring methods, which have proven reliable for decades. The delivery scope includes a measuring ring made according to standard from a high-quality, corrosion-proof platinum and iridium alloy and a glass plunger to determine the required density of the medium for the automatic ring correction. In addition to the platinum Wilhelmy plate, a temperature probe and a magnetic field stirrer are also available. The right accessories increase the range of uses of the TD 2 Technical data TD 2 Measuring mode Surface and interfacial tension; density, weight Measuring range surface and interfacial tension mn/m < 300 (ring) < 999 (plate) Resolution mn/m 0.01 Temperature range for samples C 5-85 Temperature measurement/resolution/accuracy C Digital (optional)/0.1/0.5 Density measurement /Resolution kg/m 3 < 2000 /1 Weight measurement/resolution mg < 5000/0.1 Calibration weight mg 500 Display Graphic display 320 x 240, 11 x 40 characters Measuring mode selection/parameter input Ring, plate, density, weight/menu-controlled Sample designation Numerical (0-999) Measuring point interval Minutes 1-120, selectable Data storage Results Max. 500, with date, time and measuring parameters Stage movement /Stroke speed mm/s DC motor, selectable in 10 steps from 0.1 to 0.7 Maximum detection Automatic Ring correction Automatic according to Zuidema und Waters Magnetic stirrer Control integrated; table with stirrer optional Stability criterion Standard deviation by user-defined 3to9measurements Interface/Documentation RS 232/Printer, PC (optional) Data transfer software For PC based on WINDOWS 98 SE and higher (optional) Weight kg Approx. 4.0 Dimensions measurement desk (WxDxH) mm 225 x 165 x 305 Power supply External power adapter, V; 50/60 Hz Standard accessories Du Noüy-Ring circumference: 60 ± 0.2 mm Calibration weight: 500 mg Tweezers Set of 10 sample beakers Ø 6 cm Glass immersion plunger for density fixing Plastic case for accessories Recommended accesories Wilhelmy plate: circumference: 40 ± 0.2 mm Double-walled glass thermostating vessel Set of 10 sample beakers Ø 8 cm Magnetic stirrer Digital temperature probe Data transfer software (PC) under WINDOWS Protocol printer Thermostats (see p. 40) Measuring technology standards DIN DIN ASTM D971 ISO 304 ISO 4311 ASTM D1331 ASTM D1590 ISO 6295 ISO/DIS

16 LAUDA Ring/Plate Te n s i o meter T E 3 T h e p e r f e c t s y m b i o s i s b e t w e e n p r o v e n m e t h o d a n d m o d e r n t e c h n o l o g y T h e L A U D A R i n g / P l a t e Te n s i o m e t e r T E 3.

17 A p p l i c a t i o n s TE 3 The LAUDA Tensiometer TE 3 is creating new horizons. It offers the usual surface/interfacial tension measurement technology based on the Du Noüy ring and Wilhelmy plate, plus additional options for measuring critical micellar concentrations and contact angles on solid and powdered samples and therefore also the surface energy. Thanks to the high sensitivity and extremely short response time of the new force measurement system, even hair-fine fibres can be characterized. The LAUDA Tensiometer TE 3 enables numerous measurements Surface tensions of liquids with ring or plate Interfacial tensions between two immiscible liquids (e.g. water/oil) Contact angles on solid plates with the dipping method (dynamic Wilhelmy method) Contact angle on fibres using dynamic Wilhelmy or on powders using the Washburn method Automatic concentration changes to determine the critical micellar concentration (CMC) Automatic surface aspirating for cleaning surfaces and for adsorption tests Density using the buoyancy method Example: CMC determination for different surfactants (washing agents) The CMC must be determined for different surfactants. The surfactant is added to the solution. Even with automatic control of the dosimats, the required cleaning of the dosing system when changing surfactants is time consuming. At the start of measurements, reaching equilibrium can also take up a lot of time, due to slow surface adsorption at low surfactant concentrations. Solution: The concentration changes are automatically implemented by the control of the dosimat, including homogenization and surface aspiration, by the LAUDA Tensiometer TE 3. The sample is automatically diluted with the Reverse CMC method. This method can also be used for surfactant systems that only remain in solution at higher temperatures. As the dosimat and supply tubes only ever contain water, the dosing system does not require cleaning. The CMC point is also reached rapidly as equilibrium is reached more quickly at higher concentrations. Static surface tension mn/m Surfactant 1 Standard method (slow) Surfactant 2 Reverse method (fast) CMC 1 CMC 2 Concentration mol/l Example: Characterization of wetting behavior of materials Dirt deposits on surfaces of glass, metal or polymers can be avoided by rendering the surfaces hydrophobic. The property here is the wetting angle of a drop placed on the surface (contact angle). This can be automatically measured using expensive PC supported video systems. Disadvantage: one only obtains information about the environment directly surrounding the drop. Powders and very rough surfaces are very difficult to measure in this manner. Solution: The LAUDA Tensiometer TE 3 simplifies the characterization of the wetting behavior of the whole surface. The contact angle, which is relevant for the determination of surface energy, is measured by means of the precise adjustment of the immersion/receding rate and the micrometer-accurate measurement of the immersion depth. The hysteresis curve and fine structure of the force progress provide more information, e.g. regarding the surface roughness. The Washburn method is used to measure contact angles on powders. Wetting force in mn/m (contact angle) 70 (0 ) 0 (90 ) Hydrophilic material (smooth) Hydrophobic material (rough) Immersion depth in mm 17

18 LAUDA Ring/Plate Te n s i o meter T E 3 The big brother of the LAUDA TD 2 is a highly precise all-round measurement device for all types of interfaces. Thanks to the high level of automation it is also suitable for use in quality control. It is essential for interfacial researchers due to it s high precision and the numerous measuring options. The combination of a fast, microgram accurate force measuring system with the high resolution distance encoder is the basis for the wide application spectrum of the LAUDA Tensiometer TE 3. Determination o f surface and interfacial tension Measuring and graphic display of surface and interfacial tension time dependence over a wide range, specified by the user, with linear or logarithmic measuring point distribution. Automatic maximum detection, calculation and correction of the surface and interfacial tensions using various methods Calculation of mean values and standard deviations. Determination of static thermodynamic equilibrium surface or interfacial tensions Unique o p t i o n s f or automatic determination of c ritical m icellar concentrations In standard CMC mode, the surfactant is added automatically at every concentration change by a dosimat using a diffusion-free dosing tip and the sample is then stirred. In Reverse CMC mode, patented by LAUDA, the solvent, generally water, is added by a dosimat and the appropriate portion of the diluted solution is aspirated by a second dosimat. The function of the additional dosimat can be replaced by an integrated pump. The surface is also automatically cleaned of any adsorption layers at each concentration step. The critical micellar concentration can be determined automatically, semi-automatically or manually, as required, from the concentration dependency and is stored with all individual measurements. Contact a n g l e a n d surface energies of solids Measuring of dynamic contact angle on sample plates or cylinders using the Wilhelmy immersion method Measuring of contact angle and adsorption behavior of pulverized or porous samples using the Washburn method Calculation of the solid surface energies, preferentially using the Neumann method Determination o f density By measuring the buoyancy force of a glass displacement body, the density of liquids can be determined using the Archimedes principle. 18

19 A d v a n t a g e s TE 3 The robust and reliable LAUDA Tensiometer TE 3 is extremely simple to operate and is resistant to unfavourable ambient conditions and aggressive vapors and chemicals. The large open interior simplifies the introduction of samples. If necessary, it can be protected by a detachable housing. The double spindle guide in combination with a PLL controlled DC motor provides almost total play and friction free, and therefore low vibration, stage movement over a wide speed range. The measurement unit with force measuring cell, distance encoder and thermostating sample stage with magnetic stirrer The control unit with keys to control stage movement and aspirator pump Display and graphic presentation of current values The main measuring data are displayed with very short intervals during the test. This enables the visualization of even complex wetting behavior during the movement of the measuring body in contact with the test liquid. This means, e.g. that Du Noüy measuring rings or Wilhelmy plates can be evaluated. The contact angles and therefore the surface energies of porous or powdery samples can be determined using the adsorption method according to Washburn. Special measuring methods for interfacial tension The determination of interfacial tensions with unfavourable wetting behavior of the measuring ring is also much simpler, or even possible in the first place, with the TE 3. In these cases, the minimum force for calculating the interfacial tension can be used. Connection and control of dosimats Up to two dosimats can be connected to the control unit and independently operated. This simplifies and automates, e.g. the determination of the critical micellar concentration or other concentration dependencies. An integrated magnetic stirrer ensures the necessary homogeneity of the sample. Integrated aspiration pump An integrated aspiration pump can, in combination with a dosimat, also be used to effectively and easily automate concentration changes, e.g. in dilution series. In addition, insoluble impurities or adsorption layers can be aspirated from the liquid surface. 19

20 LAUDA Tensiometer T E 3 The software offers the researcher many advantages in measuring and evaluation. For instance, the accurate determination of static surface and interfacial tension values can be implemented with statistical analysis. The force course of the measurements is displayed online. This enables wetting problems to be identified immediately. Important physico-chemical parameters of surfactants, such as the critical micellar concentration, adsorption isotherms and surface energies (solids/powders/plates or fibres) can be determined as required automatically, semi-automatically or manually. The 32 bit program is fully compatible with MS Windows (from Version 95) and can also work without problems in the background. The scope of delivery: Easy to use, intuitive program with familiar Windows functionalities Measuring and graphic display of time dependence of surface and interfacial tension with linear or logarithmic time scales Automatic maximum detection, calculation and correction of the surface and interfacial tensions Calculation of mean values and standard deviations. Determination of static thermodynamic equilibrium surface or interfacial tension Automatic control of up to two dosimats, integrated aspiration pump and adjustable magnetic stirrer simplify CMC measurements Concentration dependency can be determined logarithmically or linearly, in standard or reverse mode Adsorption isotherms can be displayed, the CMC point can be automatically or semi-automatically identified and inserted in tables Measurement and evaluation of critical micellar concentration Other options: All relevant measuring data such as wetting force, immersion depth, time and temperature are displayed online in their own windows Contact angle hysteresis can be displayed individually, advancing and receding angles are automatically determined and inserted in tables Interfacial energies are determined using the Neumann method Reports, graphics and tables generated by the user can be transferred to other Windows applications Easy calibration and test functions Contact angle measurement and interpretation Updating older models compatibility is an obligation Even users of the predecessor models, LAUDA Tensiometer TE 1 and TE 2, can now take advantage of the new options. The software runs without any modifications on the PC controlled TE 2. Even the oldest devices of the LAUDA Tensiometer TE 1 can be updated by connecting the measurement desk, together with its force measuring cell and measurement table to the control unit of the TE 2 and therefore also to the PC with just a few modifications. Optionally, for contact angle applications, a digital distance encoder can be installed. 20

21 Te c h n i c a l d a t a TE 3 The LAUDA TE 3 is configured to the application case. This saves costs and increases efficiency. One can select from the individual measuring bodies (ring/plate) for surface tension measuring and special sample supports for contact angle measuring. Depending on the external conditions and the precision required, thermostating or double protection using the glass tempering bell cover might be necessary. The same applies to the connection of dosimats to the system. LAUDA can provide the necessary accessories, including its thermostating proven LAUDA thermostats. Glass tempering bell cover protects against ambient influences Measuring probes and accessories for numerous measuring methods Technical data TE 3 Wetting force range and resolution mg Surface tension with Du Noüy ring mn/m Surface tension with Wilhelmy plate mn/m Resolution surface tension mn/m 0.01 Integrated distance encoder and max. stroke distance resolution mm Density measuring range and resolution g/cm 3 < Speed of stage movement mm/min PC controlled Temperature range for samples C Integrated magnetic stirrer PC controlled Interfaces RS 232C 1 Dimensions of TE 3 measurement desk (WxDxH) mm 240 x 240 x 600 Dimensions of TE 3 control unit (WxDxH) mm 340 x 240 x 105 Weight of TE 3 measurement desk kg 8 Weight of TE 3 control unit kg 4 Power consumption W 100 Power supply V; Hz ; 50/60 1 for connecting 2 Metrohm 765 burettes, Thermostat, PC Measuring b o d i e s Du Noüy ring Circumference: 60 ± 0.2 mm Wilhelmy plate Circumference: 40 ± 0.2 mm Plunger density measuring Boro-silicate glass (Vol: 1 cm 3 ) Sample holder for contact angle measurement on platelets and fibres Sample holder for powder Boro-silicate glass tube (Ø 1 cm with 0.1 ml scale, max. filling volume: 2 ml) Standard accessories Du Noüy ring Standard weight 500 mg Clutch fastening (for measuring body and sample holder) Tweezers Sample beakers (10 p. Ø 8 cm) Connection cable RS 232 Software for surface/interfacial tension and CMC determination Plastic case for accessories Further accessories Wilhelmy plate Contact angle set with software and sample holder for solid and powder samples Sample platform capable of thermostating with Pt 100-probe and built-in magnetic field stirrer Temperature protection bell (glass) Thermostats (see p. 40) CMC measuring accessories Measuring technology standards Reverse CMC measuring set Burette 765 Dosing and aspiration capillaries PTFE tubes and adapter DIN DIN ASTM D971 ISO 304 ISO 4311 ASTM D1331 ASTM D1590 ISO 6295 ISO/DIS

22 Dynamic methods Surface and interfacial tensions are called dynamic when their values, despite constant external conditions, decrease significantly with increasing age, i.e. when they are not in thermodynamic equilibrium. The most familiar methods for determining these dynamic values are the drop volume and bubble pressure methods. In the drop volume method, the dynamic surface or interfacial tension is determined from the volume of a falling drop. Surfactants a t i n t e r f a c e s Origin of the dynamics Air/oil phase Interface Subsurface Surface-active substances, because of their structure, prefer to migrate to surface or interfacial regions. The migration characteristics of these molecules mean that, over time, they enrich the Aqueous phase Hydrophobic component Hydrophilic component surface/interfacial regions. This constantly decreases the surface/ interfacial tension. At the same time, a few molecules manage to leave the surface/interfacial regions. If the number of molecules arriving equals those leaving, then a stable surface/interfacial tension value is reached. These dynamic effects are based on previously poorly understood surfactant properties. In many analysis cases using so-called general tensiometers (ring/plate), this effect can lead to serious measuring errors. The analysis of these effects is particularly important in time-controlled surfactant actions, such as, e.g. rapid coating processes, droplet formation in sprays and liquid jets, wetting processes or emulsion stability. The drop volume and bubble pressure methods are particularly suitable for recording these dynamic changes. Container wall Desorption Material transport The drop volume m e t h o d Determination of the dynamic surface tension and the interfacial tension between immiscible liquids Surface t e n s i o n : Drops are generated using a suitable device. These drops grow as long as their weight is less than their holding force on the capillary. As soon as this weight has reached the same level as the holding force, the drop falls and the volume of the falling drop is measured. The surface tension is then calculated from this volume. σ gρv = 2π rf HB I n t e rfacial t ension: Drops of a liquid with a high density, e.g. water, are generated in a liquid with low density, e.g. oil. Both fluids are immiscible (water/oil). As soon as the weight, minus buoyancy, reaches the same level as the holding force, the drop will fall. The volume of the falling drop is measured and the interfacial tension calculated. σ g(ρ = 1 -ρ 2 )V 2π rf HB Preferred applications: For surface and interfacial tension Particularly suitable for dynamic interfacial tensions Examples of typical samples: For solutions, oils and viscous systems that contain surfactants Particularly suitable for emulsifiers, average-speed surfactants and average surfactant concentrations 2rf HB V 22 Equipment suitable for this method: The LAUDA Tensiometer TVT 2 easy to use, robust and PC controlled (see p. 24 ff.) ρ: sample density g: acceleration due to gravity f HB: correction factor ρ 1: density of specific heavier sample ρ 2: density of specific lighter sample σ: surface and interfacial tension

23 D y n a m i c m e thods In the bubble pressure method, the pressure in a small gas bubble is used to determine the dynamic surface tension. The age of the drop/bubble can be varied in both the drop volume and bubble pressure methods. This enables specific dynamic effects to be investigated. The LAUDA Tensiometers TVT 2 and MPT C work with very wide time ranges that overlap. The Drop Volume Tensiometer TVT 2 enables measuring of interfacial tension with surface aging up to several hours. M aximum bubble p r e s s u r e m e t h o d D e t e r m ination o f t h e surface tension of liquids M easuring principle: Air is blown through a capillary into the liquid being measured. The pressure in the gas bubble formed on the end of the capillary rises. Maximum pressure is reached when the bubble reaches the hemispherical shape. At this point in time, the radius of the hemispherical bubble corresponds to the radius of the capillary. Once the hemispherical shape is exceeded, the pressure only serves to expand the bubble until it detaches itself. The surface tension can be calculated with the Laplace equation from the maximum bubble pressure and the bubble radius. The time from the start of bubble formation to the hemispherical shape (maximum pressure) is the surface age corresponding to the surface tension. The time from the hemispherical shape until the bubble detaches is the dead time. It is not relevant for the measurements. σ = ; P h =ρ g h r cap (P max P h ) 2 h: immersion depth ρ: sample density g: acceleration due to gravity σ: surface tension r cap: capillary, internal radius P max: maximum pressure P h: hydrostatic pressure P referred a p p l i c a t i o n s : Dynamic surface tension For systems containing surfactants Examples of typical s amples: Very rapid surfactants and/or high surfactant concentrations E q uipment s u i t a b l e for this method: The MPT C: it enables precise determination of dynamic surface tension with surface ages measured from fractions of milliseconds up to 2 s (MPT C) (see p. 30 ff). L AUDA Tensiometers s u p p l e m e n t e a c h o t h e r Surface tension σ [mn/m] MPT C TE 3/TD 2 30 TVT Surface age [s] If depicted in a logarithmic way the surface tension/surface age is an S-shaped curve which is characteristic for each surfactant and its concentration. Each of the LAUDA Tensiometers covers a certain range of the surface age for physical-technical reasons. The range defined by the application is therefore the deciding criteria in selecting the equipment. Using the combination of different LAUDA Tensiometers provides nearly complete coverage of the time range. 23

24 LAUDA Drop Vo l u m e Te n s i o m e t er T V T 2 Drop by drop, the LAUDA TVT 2 can measure very small dynamic interfacial tensions as precisely as the surface tensions for highly viscous samples.

25 A p p l i c a t i o n s TVT 2 The LAUDA Drop Volume Tensiometer TVT 2 is used to measure the surface and interfacial tension of liquids. Its strengths lie in the high-precision determination of dynamic interfacial tension. The TVT 2 uses the characteristic that the volume of a drop released from a needle in air is dependent on its surface tension or on its interfacial tension between the two phases if released into a second, immiscible phase (oil). This measuring principle has been realised in a measuring device that is easy to use thanks to precision engineering and modern electronics. The TVT 2 is a suitable device for many applications that cannot, or only partially, be evaluated by other devices. Characterization of the dynamic behaviour of surfactant molecules at the surface and interface within seconds or hours High-precision measuring of interfacial tensions in a very wide range down to very small values (0.1 mn/m) Measurements on highly volatile and/or toxic substances through gas-tight system sealing No wetting problems as occurs, for example, with ring, plate and frame methods Low sample requirements (0.25 ml to 5 ml) Simple thermostating options over a wide temperature range ( C) Measurements of rising and falling drops Syringes and needles for various applications Highly viscous and skin-forming liquids are easily and rapidly measured E x a m p l e : We t ting a g e nt concentration in galvanic baths Wetting agent concentrations in galvanic baths must be evaluated as rapidly and simply as possible. Ring/plate tensiometers cannot record any concentration differences for evaluation. S o l u t i o n : The dynamic surface tension of baths containing surfactants shows a significant dependency, even at concentrations that are greater than the critical micellar concentration. Reproducible drops with defined lifetime can be generated with the TVT 2. The surface tension/concentration dependence can be represented as a reference curve and this can then be used to determine the wetting agent content of other samples. E x a m p l e : S c r e ening tests of emulsifiers To facilitate pre-selection of suitable emulsifiers for stabilizing emulsions, the interfacial activity and adsorption behaviour must be determined as rapidly and simply as possible. Normal ring/plate tensiometers are suitable for this only to a certain extent. Dynamic surface tension mn/m σ 1 50 σ 2 25 σ(c), Drop age = 10 s C 1 C 2 Wetting agent content C S o l u t i o n : The dynamic interfacial tension at the interface between the two phases shows, in addition to the interfacial activity, how fast emulsifiers reach the interfaces. Reproducible aqueous drops with variable lifetimes in the oil phase can be generated with the TVT 2. This can be used to determine the interfacial tension dependent on the interface age. The extrapolation to infinity provides the thermodynamic equilibrium value. Dynamic surface tension σ (t ) 5mN/m slow emulsifier extrapolated fast emulsifier measured 2 0 1/ t t Drop age 25

26 LAUDA Drop Vo l u m e Te n s i o m e t er T V T 2 The LAUDA Drop Volume Tensiometer increases the options for measuring dynamic surface and interfacial tensions. With the TVT 2, time-critical functions, such as drop monitoring and speed control, have been moved from the PC to a powerful microprocessor. This means that the instrument can be controlled under Windows with minimum loading of the computer, even when multi-tasking. New functions, such as e.g. individual drop measuring of up to 100 drops, are now possible. The LAUDA Tensiometer TVT 2 consists of a measurement desk and a control unit. The core of the electronic component is a microprocessor that controls the Simple f u n c t i o n principle for highly precise results Syringe needle Aqueous phase Light sensor Position Motor Control unit PC RS 232 Sample drops are produced by the plunger being pushed into a needle with a known diameter. The syringe plunger path l is measured to the micrometer with a high-resolution distance encoder and the speed is precisely adjusted and controlled by the PLL control system. At a certain size, determined by the holding force (see Dynamic methods ), the drop breaks away and falls into a collection tube. As it does so, it is recorded by the light sensor, which transfers the data to the microprocessor. This then measures the distance of the syringe plunger and determines the time from the precursor drop. This data is transferred from the control unit via the RS 232 to the PC. There the drop volume V is calculated from the distance l and the cross-section area A of the syringe and this is used to determine the surface/interfacial tension taking into account density difference. Oil phase (air) I F F σ G F F σ G F F σ G V By multiplying the distance l of the syringe plunger with the known crosssection area A of the syringe, one obtains the volume V of the falling drop and therefore the surface/ interfacial tension (see Dynamic methods ). The drop grows: The weight of the drop increases, but is still smaller than the holding force. F G < F σ The drop grows to a maximum, where the weight of the drop just compensates for the holding force. F G = F σ The drop then falls and is detected. The growth of the next drop begins. F G << F σ 26

27 A d v a n t a g e s TVT 2 discharge speed, counting the encoder pulses and provides communication. LED s and pictograms indicate the current status of equipment. Keys are provided for positioning the syringe plunger also in offline operation. Communication with the operating PC during online mode is enabled via an RS 232 interface. The measurement desk contains the easily replaceable and thermostable syringe, the light barrier, a high-resolution distance encoder and the precision mechanics for drop generation. This m a kes the T V T 2 unique The excellent precision and reproducibility of the measuring values provided by the TVT 2 are due to, amongst other factors, the following technical equipment: Individual drop volume determination Positioning accuracy in micrometer range Variation of advance speed by a factor of 300 through the PLL speed control Automatic adjustment of advance speed to actual volume status of drop Automatic adjustment of light sensor intensity to suit the liquid used Simple application of various syringe/needle combinations and sizes Quasi-static mode for very high surface ages Measurement desk with high resolution distance recording Control unit with keys and RS 232 interface for communication between measurement desk and PC T h e u n d e r l y i ng p r e cision t echnology Ground, precisely measured spindles Consists of a discharge device, driven by PLL-controlled, low-vibration DC motor High-resolution, micrometer-precise distance encoder for volume determination High-quality gas-tight syringes with constant internal diameter Drop formation needles made from steel or glass, for rising and falling drops Optical, electronically controlled drop sensor Hermetically sealed collection tube Sturdy construction, no problems with corrosive or toxic samples Syringe and cell can be thermostated to 60 C, or optionally 90 C, with LAUDA thermostats 27

28 LAUDA Drop Vo l u m e Te n s i o m e t er T V T 2 The dialogue-based, self-explanatory user guidance on the PC with MS-Windows (from Version 95) and the sturdy, easy to operate mechanics means that it can be used even by untrained personnel. The software provides test guidance, optimized for the applications, and many options for graphic and tabular representation and output of measuring data. The scope of delivery: Simple software installation Self-explanatory Windows user guidance Output of recorded measuring data in graphic or tabular form to standard printers Data back-up of measuring data on various media or further processing with standard programs Tabular online presentation of a dynamic measurement Other options: Online calculation of the determined surface/interfacial tensions Standard mode for determination of surface/interfacial tension in rapidly adsorbing and surfactant-free systems Two measuring methods for characterizing the adsorption behaviour of surfactants A) by varying the drop formation time B) by determining the drop separation time at a given drop volume Representation of recorded measuring data in tabular or graphic form on-screen (up to 5 test series in one graphic) Extrapolation to static values (equilibrium) even with very slow surfactant adsorption through fitting of theoretical curves Automatic measurement of the temperature dependency (only in conjunction with LAUDA thermostats from the E3xx range see p. 40) Graphic presentation of a dynamic measurement 28

29 Te c h n i c a l d a t a TVT 2 To precisely record the drop sizes that can vary widely during interfacial tension measurements and provide sufficient drops for series measurements, syringes with 0.25 ml 5 ml volumes and needles with various diameters and materials can be used. Rising drops can also be measured with the Reverse measuring set. Moreover, the use of disposable needles/cannulae makes cleaning superfluous, which significantly simplifies and speeds up routine measurements. Simple to change: syringes of various volumes and needles for falling and rising drops Technical data TVT 2 Measuring range mn/m Resolution Stroke µm 0.1 Volume µl 0.01 Surface/interfacial tension mn/m 0.01 Drop formation time s 0.1 Reproducibility of individual drops for pure liquids (mechanical tolerances): Stroke µm < 2.5 Volume (with reference to syringe volume) µl 0.07 Surface tension mn/m 0.08 x Syringe volume [ml] 1 Interfacial tension The above value must be multiplied with ρ (density difference) Drop formation time for t < 100 s 2 s Reproducibility of mean value over 5 drops Surface tension (depending on syringe and needle type) mn/m Absolute accuracy approx. 0.5 % of end value of surface tension Drop times s/µl 0.04 (at 5 ml) 170 (at up to 0.25 ml) Speed control < 1 % Temperature range C 5 60, 5 90 (with special thermostating block) Interfaces RS 232 Dimensions of TVT 2 measurement desk (WxDxH) mm 220 x 240 x 555 Dimensions of TVT 2 control unit (WxDxH) mm 340 x 270 x 105 Weight of TVT 2 measurement desk kg 8.0 Weight of TVT 2 control unit kg 4.2 Power consumption W 0.1 Power supply V; Hz ; 50/60 Standard accessories Software RS 232 cable Mains cable Connecting cable measurement desk/control unit Light barrier cable (transmitter and receiver) Syringe 2.5 ml Standard needle SK1 Cell Thermostating block (60 C or 90 C model) Allen key Cell handling tool R e c o m m e n d e d accessories Syringe with various volumes Thermostating block (max. 60 C or alternatively 90 C) Spare screw cap for needles Temperature probe Cell handling tool Adapter RS 232 cable Steel needle Reverse needle Glass needle Cell (heat-proof glass) Reverse measuring set Thermostats (see p. 40) Disposable syringes and cannula 1 this means, for instance: Syringe volume [ml] σ[mn/m] ± 0.02 ± 0.04 ± 0.08 ± 0.16 ± depending on drop size and discharge speed Measuring technology standards ISO 9101 ASTM D

30 LAUDA Bubble P r e s s u r e Te n s i o m e t e r M P T C T h e h a n d y L A U D A B u b b l e P r e s s u r e Te n s i o m e t e r M P T C a l s o r e c o r d s f a s t s u r f a c t a n t s i n m i l l i s e c o n d r a n g e. 30

31 A p p l i c a t i o n s MPT C The bubble pressure tensiometer MPT C has been added to the family of LAUDA tensiometers. As opposed to scientific research tensiometers as the MPT C the final step has been taken for the full automation of dynamic surface tension measuring. Ultimate user-friendliness is achieved without having to take a detour via the PC. The extremely compact stand-alone device offers all the necessary features for the simple measurement of dynamic surface tensions in the laboratory or as a mobile device. Exact measurements of the dynamic surface tension independent of a PC The measurements are precise and reproducible, yet time-consuming settings can be presented, stored and transferred to a PC at the touch of a button. The measuring method according to Fainerman also guarantees exact surface tensions at even extremely small surface ages and the accompanying real bubble age. The program offers two measuring procedures. In the first mode, the bubble frequency is reduced in stages, whereby a specified flow range is gradually passed through in order to clearly determine and represent the dependency of the dynamic surface tension from the surface age. The flow is re-adjusted at every single measuring point and is identified as measured value. The evaluation of the measurements and the necessary correction, such as for calculating the dead time, is carried out on a scientifically-founded base. In the constant flow mode, the bubble frequency and, thus, the surface age, is kept constant in order to document any changes in the surfactant concentration, e.g. in the course of reactions. Various areas of application Thanks to the self-explanatory user guidance, the simple cleaning of the capillaries as well as the compact structure of the unit, the unit is especially suitable for the quality control of dynamically-critical surfactant solutions or for the fast determination of a surfactant at concentrations above the critical micelle concentration. The MPT C is robust, user-friendly and highly precise. Measurements are carried out completely independently by the user and documented along with the necessary settings. Thus complying with the strict specifications of the GLP guidelines. Example: optimisation of the surfactant dosage It is only by measuring the surface tension of extremely short-lived surfaces of washingup liquids that the surfactant content can also be determined above the critical micelle concentration and be optimised directly in the process or a dosage formula be developed from it. S o l u t i o n : The MPT C allows fast and easy measurements of surface tension even at high concentrations of surfactants. Precise determination of concentration is possible due to an extremely large dynamic range from 1 millisecond up to several seconds. Dynamic surface tension mn/m σ 1 50 σ 2 25 Calibration characteristic for surface age = 100ms C 1 C 2 Concentration of washing surfactants C 31

32 Applications M P T C Example: O p t i m i zation of drop size The drop size in sprays, e.g. for agrochemicals, cosmetics or inkjet printers, is dependent on the surface tension immediately after leaving the nozzle. The surfactants that produce the right drop size must rapidly reduce surface tension. Normal tensiometers are too slow to measure these rapid changes. Solution: The dynamic surface tension is measured by the MPT C on surfaces that are only a few hundredths of a second old. This corresponds to the age of the droplet immediately after leaving the nozzle. This allows suitable surfactants to be selected and their concentration is optimized. Dynamic surface tension σ (t) [mn/m] 50 Surfactant too slow σ (0.01 s) = 58 mn/m s Surface age [s] Suitable surfactant σ (0.01 s) = 33 mn/m Example: D e t ermination of surfactant c onsumption The surfactants consumed during the washing processes are measured online via the changes in surface tension. Normal tensiometers were found to be unsuitable for this process as the surfactant concentration always lies significantly above the critical micellar concentration (CMC). Solution: The dynamic surface tension shows a clear dependency on concentration at surface ages of 0.01 s, even above the CMC. This means that the MPT C can determine the effective surfactant concentration and hence surfactant consumption. Dynamic surface tension σ (c ) [mn/m] 50 σ σ (0. 01 s) x CMC CMC 10 x CMC Concentration c Dosing range for washing surfactants 32

33 L A U D A B u b b l e P r e s s u r e Te n s i o m e t e r MPT C The ergonomic measurement desk contains the sensitive pressure sensors and the holder for the capillaries included as standard accessories, humidifier and sample beakers. A temperature probe, combined with a LAUDA thermostat guarantees the stability of the temperature. The measuring capillary can be inserted directly into the reaction vessel via a hose connection up to one metre in length or via a flow cell (bypass) for the online monitoring of the surfactant reactions. Simplest handling via external remote control The external, handy remote control Command with a graphic display can be intuitively used without the need for any special know-how. The integrated microcontroller offers a series of useful testing methods with which, for example, it can automatically carry out a scan of the dynamic surface tensions over a range of 1 to 2000 milliseconds, thus recording the adsorption kinetics of even very fast surfactants in a complete, comprehensive manner. The scope of delivery: Extremely large dynamic range from 1 ms up to several seconds Automatic recognition of the transition point bubble/jet range Tabular representation of the dynamic surface tensions, number of measured points, real bubble age Graphic representation of the dependency of the dynamic surface tensions on the bubble age, linearly or logarithmically User-defined measuring point distance and duration of the measurement Storage of up to 50 measure results including the accompanying parameters Clear presentation of the measuring results Other options: Numerical description of samples determined by the user Output of the measured values on an optional printer or PC via RS 232-interface Plug-in boards with relay output in order to control the processes via the surface tension High-resolution pressure sensors guarantee the precise pressure logging Measuring with double-walled thermostating vessel 33

34 Advantages a n d t e c h n i c a l d a t a M P T C Output of the measured values is optional via a printer or a data transmission software on the PC via the RS 232-interface. The measurement and the documentation of the temperature in the sample can also be carried out by means of an optional digital temperature probe. Steel and glass capillaries for various samples Complementary accessories simplify work Technical data MPT C Measured value Measuring methods Dynamic surface tension Constant flow, automatically changed volume flow, constant surface age Resolution mn/m 0.1 Measuring range of surface tension mn/m 10 to 100 Dynamic range s 0,001-2 Monitoring mode constant flow min. 1 to 60 and more Temperature range (sample) C 5-85 Temperature measurement Digital (optional) Resolution C 0.1 Precision C 0.5 Display mm 320 x 240 graphic display, 11 x 40 characters Display modes Tabular, graphic: surface tension as a function of the surface age (t, Lg t) Selection of measuring mode Menu-controlled Parameter input Menu-controlled Sample description Numerical Measuring point distance mode constant flow min. Selectable Data storage Max. 50 results with date and time Duration of experiment min. 3 to 20 (depending on the measuring point density) Interfaces RS 232 Documentation Protocol printer, PC (optional) Data transmission software For PC running WINDOWS 98 and higher (optional) Weight kg Approx. 6.5 Dimensions (WxDxH) mm 280 x 300 x 300 Power supply V External power adapter, V; 50/60 Hz Standard accessories Two glass capillaries Set of beakers to take samples Further accessories Digital temperature probe for measuring in the sample Data transmission software for PC under WINDOWS (optional) Double-walled thermostating vessel Diverse types of capillary Protocol printer Membrane pump for capillary rinsing Online flow cell Rinsing set Measuring standards ASTM D

35 L A U D A E c o l i n e S t a r e dition Heating and cooling thermostats for cost-effective thermostating in laboratories from -20 to 200 C R ecommended L A U D A t h e r m o s tats f o r t e n s i o m e t e r s The right thermostat Ring/plate tensiometer TD 1 C Ring/plate tensiometer TD 2 Ring/plate tensiometer TE 3 Drop volume tensiometer TVT 2 Bubble pressure tensiometer MPT C Bubble pressure tensiometer MPT 2 = recommended thermostat up to 150 C E100 LCD display, resolution of indication 0.1 C Symbols to show operating status Simple 3-key operation User-friendly menu guidance Display of actual or set temperature Overtemperature protection Low-level protection Vario pump technology Audible alarm Fault report with automatic self-tests Facility for calibration Enlarged temperature range up to 150 C E 103 E 203 E 306 RE 104 with E 200 (as E 100, but additionally) 2-line LCD display, resolution of indication 0.05 C Parallel display actual/set temperature Setting resolution selectable C or 0.01 C Messages of operating states in clear text Remote fault indication through floating contact RS 232 and RS 485 interfaces 2-point factory calibration as standard Basic-Programmer for 20 temperature/ time segments, with loop, alteration and pause function RE 204 RE 306 Programmer with LAUDA Wintherm Plus PC software E 300 (as E 100/E 200, but additionally) Back-lit 2-line LCD display, resolution of indication 0.05/0.01 C External control Screw-on nipples with M 16x1 thread Mains voltage outputs for solenoid valve for controlled cooling with mains water or to operate through-flow cooler Analogue inputs and outputs V or 0/ ma with standard signals e.g. for peripheral equipment Remote control as accessory Programmer for max. 150 temperature/time segments, devided into 5 programs with loop, alteration and pause function LAUDA Wintherm Plus PC software controlled with any PC by interfaces 35

36 Thermostats LAUDA Ecoline Staredition cooling baths of various sizes made of high-quality stainless steel are made to measure for all of your wishes and provide optimum cooling and heating curves thanks to their insulation. All of the Ecoline Staredition cooling thermostats are equipped with power-saving automatic cooling control. All the units have carrying handles and a drain tap. The panel with the ventilation slots at the front can easily be removed for cleaning. LAUDA Ecoline Staredition thermostats offer you the top digital technology that is indispensable in the laboratory of today. In order to get only as much technology as you actually require, we have provided the Ecoline Staredition with three different control heads with different performance packages. You only pay for what you actually need. Cooling thermostat RE 306 Heating t h e r mostats Technical features E 103 E 203 E 306 Working temperature range C Temperature stability ± C Heating power kw Discharge pressure max. bar Pump flow max. L/min Bath volume L Bath opening*/depth mm 135x105/ x105/ x130/160 Cat. No. 230 V; 50/60 Hz LCB 0691 LCB 0692 LCB 0699 Cooling t h e rmostats 36 Technical features RE 104 RE 204 RE 306 Working temperature range** C Temperature stability ± C Heating power kw Cooling output at 20 C kw Discharge pressure max. bar Pump flow max. L/min Bath volume L Bath opening/depth mm 130x105/ x105/ x130/160 Cat. No. 230 V; 50/60 Hz LCK 0861 LCK 0862 LCK 0866 * Dimensions of bath opening are overall dimensions of the bath which are slightly reduced downwards. ** Working temperature range is equal to ACC-range.

37 K e y c a p a b ilities We have been in the business of thermostating and measuring technology for more than 50 years. The precision equipment from LAUDA is highly esteemed worldwide in all branches of research and industry. Thanks to our worldwide sales service network, we have a presence in over 70 countries around the world. Our key capability, in addition to thermostating liquids, is the precise static and dynamic measuring of surface and interfacial tensions, together with the viscosity of liquids and polymer solutions. We set the standards around the world LAUDA is a pioneer in the development of automatic interfacial measuring systems. We have produced, e.g.: The first automatic film balance The first fully automated tensiometer The first computer-controlled film balances and tensiometers More than 30 years experience in implementation of scientific measuring methods guarantees user-friendly series instruments. The automated process introduced by LAUDA for the determination of the critical micellar concentration is a global standard. Special variants, such as, e.g. Reverse CMC are patent protected. The sturdiness of our devices speaks for itself: Most LAUDA instruments are still in operation today. The high LAUDA quality standard has been certified by DIN EN ISO 9001:2000 and is to be renewed every 3 years. LAUDA devices comply with international standards EN and EN , the EMC and low voltage directives.they are particularly well known for their safety in long-term operation. Our competence carries you further Your individual requirements are met by experienced and specialist engineers and designers in the fields of measuring instruments, microprocessor electronics, firmware and hardware, together with software specialists. We provide you with solid and professional support in the area of surface/interfacial measuring instruments with globally recognized experts who have long-term national and international experience. The LAUDA Service Center and specially trained service technicians at the LAUDA representational centres help you rapidly and unbureaucratically. We can also help you with questions that go beyond the area of interfacial technology, e.g. regarding viscosity or thermostating technology, and we can provide you with competent contacts. Specially for you We not only support you in the maintenance and calibration of your equipment, but also in the installation, adaptation to your requirements and interpretation of the results obtained. On request, our experts can advise you on-site. We offer a sample service before purchase to ensure that your samples can be measured. We take time for our customers: We offer you individual solutions and personal consultation by telephone or . Our sales network guarantees you qualified service practically around the entire world. Regular seminar with globally recognized experts in theory and practice of interfacial technology and important applications provide you with further training and exchange of experiences in neighbouring fields. Our strength is our service The continual updating of products and software broadens the range of possible applications. Special update contracts serve as prevention and guarantee unbureaucratic help in the case of technical problems. Our manuals support you in the optimal use of our hardware and software. They include the theoretical background of methods and equations, together with help for evaluation and interpretation, and a comprehensive bibliography. The proven LAUDA Thermostats provide all measuring instruments with optimal thermostating technology from our own company. We guarantee long-term supply of spare parts and a wide range of accessories. Rapid delivery times ensure that you are always on time. 37

38 Glossary Important terms in tensiometry Adsorption is the accumulation of (amphiphilic) molecules at the surfaces and interfaces of liquids and solids. This leads, amongst other things, to a reduction in surface/interfacial tension. Bubble Pressure Tensiometer is used to determine the surface tension of liquids from the pressure in gas or air bubbles that are generated in the measuring liquid with a capillary of known dimensions. This method is not suitable for determining interfacial tensions between liquid phases. CMC measuring is the determination of the surfactant concentration at which the surfactant molecules begin aggregating into micelles (CMC concentration). This can be determined from the dependency between the concentration of the surfactant in the solution and the surface tension. Contact angle/contact angle measuring characterizes the wetting properties of liquids on solid bodies. The contact angle can be determined by measuring individual drops on a solid or from the forces required to move a solid in contact with a liquid lamella. The contact angle is used to calculate surface energy. Correction as per Harking and Jordan Harkin and Jordan produced tables for correcting surface and interfacial tensions measured with a ring. These values are standardized. Correction as per Zuidema and Waters Zuidema and Waters developed a polynomial for correcting surface and interfacial tensions measured with a ring. Critical micellar concentration (CMC) At this concentration, surfactant solutions suddenly change their physical properties. The reason for this is the formation of organized aggregates (micelles) of the surfactant molecules when the critical micellar concentration is exceeded. The structure of the micelles is dependent on the character of the solvent and the structure of the surfactant molecules. Diffusion coefficient characterizes the thermal migration movements of molecules in the material examined. In tensiometry, the diffusion coefficient refers to the migration of molecules in the liquid measured. Drop Volume Tensiometers determine the surface/interface tension of liquids at the moment of drop separation, from the volume of the drop that is formed in air or in an immiscible second liquid. The densities of the phases concerned must be known in order to calculate the surface/interface tension from the measured drop volume. Du Noüy ring is a measuring body made of a platinum-iridium alloy to determine surface/interfacial tension from the tensile force of a lamella produced by this body using a Ring/Plate Tensiometer. Du Noüy ring method is used to measure the surface/interface tension using a standardized ring with a ring/plate tensiometer. The ring is immersed in the liquid and then drawn out. This forms a liquid lamella that is stretched to its maximum. The surface/interface tension is calculated from the resulting force. The calculated value must be corrected. Dynamic interface or surface tension is the measurable reduction in interfacial/surface tension with time due to adsorption of surface active substances. Dynamic measuring process (tensiometry) is used to calculate the surface/interfacial tension dependent on surface age. Emulsion is a disperse system consisting of two immiscibel liquids, such as water or an aqueous solution and an organic. The dispersed or inner phase is present in form of small droplets, surrounded by the dontinuous or matrix phase. Interfacial energy is the sum of free energy of all the molecules present in the interface between different materials. The interface between a liquid and a gas is designated as the surface and the corresponding energy from this region is the surface energy. Interfacial tension is the work that must be applied to increase the interface of the liquid by one surface area unit. This is equivalent to the specific interfacial energy. Lenard frame simple test wire. Is used as an alternative to the Du Noüy ring. Reverse CMC Reverse CMC is the determination of CMC by automatically reducing surfactant concentration. This measuring method is based on a LAUDA patent. It is faster and offers significant advantages in handling compared to other methods. Ring/Plate Tensiometers measure the force with which a lamella attacts a Du Noüy ring or Wilhelmy plate. This is used to calculate the surface/ interfacial tension between liquid phases. Ring/Plate Tensiometers are also used for dynamic contact angle measuring and CMC measuring with software controlled burettes. Surface age is the age of a surface since its creation. In bubble pressure tensiometry, this is the period from the beginning of bubble formation to the hemispherical shape of the bubble. In drop volume tensiometry, this is the period between the creation and separation of a drop. Surface tension is the interfacial tension between a liquid and any gas. Surfactant is a interfacially active substance. The reason for this activity is an asymmetric structure of the surfactant molecule, consisting of a hydrophobic (water-repelling) part and a hydrophilic (water-soluble) part. The interfacial tension is reduced by the adsorption of these molecules at the interface. Suspension is a disperse system, i.e. a fine, but not molecular distribution of a solid body in a liquid. Washburn method The contact angle is calculated from the weight increase over time of powders in contact with liquids. Wilhelmy plate is a standardized plate, usually made of a platinum alloy. It is used to measure surface tension with a Ring/Plate Tensiometer. The material of the plate is selected so that its contact angle to the test liquid is equal to zero. Optimal cleaning, e.g. by in a Bunsen flame, is essential. Wilhelmy plate method is used to measure the surface tension using a standardized plate with a Ring/Plate Tensiometer. The plate is moved towards the surface until the meniscus connects with it. The surface tension is calculated from the resulting force. Due to uncertain wetting behaviour, the plate can only be used for interfaces under certain limitations. 38

39 Vi s c o s i t y m e a s u r i n g s y s t e m s PVS This page offers you an other brochure of the our product range: LAUDA measuring instrumentation Viscosity measuring systems PVS The right temperature worldwide LAUDA Measuring instrumentation: Viscosity measuring system PVS Request the free copy of the LAUDA Viscosity measuring systems PVS brochure. 39

40 Our product lines: Thermostats Circulation chillers Water baths Heating and Cooling systems Viscometers Tensiometers LAUDA DR. R. WOBSER GMBH & CO. KG P.O. Box Lauda-Königshofen Germany Phone: +49(0) Fax: +49(0) Internet: e-4/3.09