Simplifying the Peel Test and Peel Test Validation. Natalya Peskin Senior Biomedical Engineer Microsurgical Technology

Transcription

1 Simplifying the Peel Test and Peel Test Validation Natalya Peskin Senior Biomedical Engineer Microsurgical Technology

2 Acknowledgements I would like to thank Savannah Hoover for all the help with testing. Abbott Associates, PRENT Corporation, Oliver-Tolas and SreriPax for providing sample materials for testing. Microsurgical Technology for providing an opportunity to perform this study.

3 The Goal of the Study ASTM F88/F88M 2015 (Standard Test Method for Seal Strength of Flexible Barrier Material) has many requirements and provisions. The standard allows to deviate from the prescribed regiment if it does not impact the test results. We looked at the ASTM F 88/F88M critically and evaluated how we could adapt the test method without affecting the final results. The following test parameters were evaluated: Seal conditioning prior to testing Tolerance on sample width Grip separation/sample positioning Rate of separation.

4 Tested Materials Sample type Material #1 Material #2 Adhesive Tray material Polycarbonate Tyvek 1073B 24AL with Tyvek lid PETG Tyvek 1073B 34NP PETG Tyvek 1073B CR27 MEDEX Tyvek 1073B CR27 Tyvek pouch 48PET/200 LDPE Tyvek 1059B none Paper pouch Mylar Paper none Foil pouch* Ofoil 48 Ofoil 48 Q15 Steriflex -31P Steriflex -31P none Plastic pouch* Nylon co-extrusion Nylon co-extrusion none Polyester coextrusion Steriflex-101 Polyester co-extrusion Steriflex-101-W *MST did not previously have experience with these materials none

5 Test Set Up Shimpo vertical test stand Shimpo gauge Film grips 1 hand-held sample cutter 90 stainless steel angle Stainless steel protractor Stainless steel rulers

6 Test Method Flat stock was tested. Pouch materials were tested with unsupported tail unless otherwise noted. Tray materials naturally have 180 supported tail. Unsupported tail 180 supported tail Max peel force was recorded for all the tests. Statistical analysis was performed using MiniTab17 software (95% confidence level). Each data point is the average of minimum 30 measurements. Approximately 3,600 peel tests were done for this study, almost 6,000 data points were analyzed.

7 Seal Conditioning Standard requirement Minimum 40-hr seal aging before testing (per ASTM E171). Potential issue Waiting for 40 hrs. may not be practical. If seal strength changes during the first 40 hrs. after sealing, we need to know. We tested The samples of the same seals were tested at various time intervals after sealing (5 min 100+ hours).

8 Peel force, lb/in Seal Conditioning No significant changes after 1 hr. No change after 24 hrs. P=0.876 Changes after 40 hours p< min 1 hr. 24 hrs. 40 hrs hrs.

9 Sample Width Tolerance Standard requirement Potential issue Sample width tolerance +/-0.5% (per ASTM D882). For 1 seal it is ± Tolerance ± is very difficult to reliably achieve or measure. We tested Peel force of samples with width 0.73, 1 and 1.5. Measured width of samples of different materials cut with the same 1 cutter.

10 Peel force, lb/in Peel Force vs. Sample Width R² = R² = Tyvek pouch Paper pouch Seal width, in

11 Sample width % samples ±1.4% 95% samples ±1.3% % samples ±1.8% Medex/Tyvek (calipers) Paper Pouch (Toolmakers microscope) Foil Pouch (Toolmakers microscope)

12 Sample Width Measuring with calipers

13 Sample Width Optical measurement:

14 Sample positioning Standard requirement Potential issue Initial grip separation 1 for less extensible material. Recording grip separation, measuring ±2%. Seal line perpendicular to the pull direction Cannot be achieved with some samples. Precise grip positioning is time-consuming. We tested Peel force with 1 grip separation Peel force with 3 grip separation Peel force with asymmetric 2 grip separation Samples cut under 90, 85 and 75 angle

15 Grip Separation Standard (1 ) Elongated (3 ) Asymmetric (2 )

16 Peel force, lb/in Sample Positioning Statistically equivalent (p>0.05) 13% up P= % up P<0.001 Equivalent P= Tyvek/Mylar Paper/Mular PC/Tyvek Nylon Polyester Ofoil, free Steriflex, Steriflex, tail free tail 180 tail 1" grip separation 3" grip separation (MST seal) 2" asymmetrical (long clear/short opaque) 2" asymmetrical (short clear/long opaque) (pre-made seal)

17 Sample positioning, angle Sample cut at angle to seal, grip parallel to seal Sample cut at angle to seal, grip parallel to the side

18 Angles

19 Sample positioning, angle Angle Peel force for ample cut at angle to seal, grip parallel to seal Peel force for sample cut at angle to seal, grip parallel to side 85 o (5 off) 75 o (15 off) Equivalent to perpendicular sample (p=0.186) 3% decrease comparing to perpendicular sample (p=0.012) Equivalent to perpendicular sample (p=0.968) 7% decrease comparing to perpendicular sample (p=0.028)

20 Rate of Separation Standard requirement Potential issue Rate of separation 8-12 in/min The rate is not representative of use. Some equipment does not support this range. We tested The samples from the same seals were tested at separation rates between 2 in/min and 16 in/min.

21 Peel force, lb/in Rate of Separation Peel pouch MST seals Peel Pouch pre-made seal PETG-Tyvek-34NP Steriflex foil pouch Rate of separation, in/min

22 Standard deviation, lb/in Rate of Separation, standard deviations Peel pouch MST seals Peel Pouch pre-made seal PETG-Tyvek-34NP Steriflex foil pouch Rate of separation in/min

23 Occurence Putting Things in Perspective Peel Strength of Sterilized Peel Pouches Mean=2.69 lb/in STDEV=0.597 N=1956 Peel force, lb/in With 95% confidence of 95% compliance the peel force will be 2.69±1.2 lb/in(±45%)

24 Summary Based on our test results: 40-hour conditioning could be unnecessary in some cases and insufficient in others. Test your materials, determine the aging profile. Width tolerance ±0.5% is probably unrealistic. Measure what you can achieve, compensate for the error when setting the acceptance criteria. Precise grip positioning is not critical for most materials. Test what variation your can tolerate. Changes in the rate of separation affect peel test results (increase in rate corresponds to increase in results, more noticeable at lower rates (2-8 in/min). Consistency of data is about the same at separation rates 2 in/min -16 in/min.

25 Conclusion Adapt application of ASTM F88/F88M to your situation: Know your materials (aging, impact of sample positioning). Understand your process capabilities. Be realistic about what you can achieve and measure. Build the impact of potential variations into your acceptance criteria. If you do this work upfront, it would make validation of peel test method and future testing simpler and easier.

26 Thank you for your attention. Questions??? Feel free to contact me at