Available at: http://digitalcommons.calpoly.edu/theses/169
Date of Award
MS in Engineering - Biomedical Engineering
Biomedical and General Engineering
In order to take advantage of the properties of poly(styrene-isobutylene-styrene) PIBS and PIB based blends as lead insulation materials, they must be able to sufficiently bond to the various materials that make up the cardiac device. The bonded PIBS must be able to withstand the mechanical stress and corrosive environment of the human body due to the long term use of these devices. Based on the component requirements of lead insulation, the first objective of this study was to perform an initial screening of multiple PIBS / stainless steel / silicone adhesive combinations. The specific polymers of interest were PIBS, 10%55D polyurethane, 10%75D polyurethane, 10%PP, and a silicone control. Based on the bonding shear strength results of the initial screening, the best performing combinations were artificially aged to simulate their resistance to degradation in vivo. Each combination was subjected to both 3% hydrogen peroxide and Phosphate Buffered Saline solutions for a period of 8 weeks to test for oxidative and hydrolytic stability. Bonding shear strengths for all sample groups were tested at each 2-week period. The 10%55D sample group had the highest mean bonding shear strength at .5602 MPa, but to observe the aging stability of all sample groups, all combinations were used in Phase II. The phosphate buffered saline solution in Phase II caused no significant decrease in bonding shear strength for all sample groups. Alternatively, oxidation caused by the 3% hydrogen peroxide solution did significantly affect the bonding shear strengths of all sample groups (minus the silicone control). Over the 8-week period PIBS degraded 28% and 10%55D and 10%75D decreased 40.0% and 30.8%, respectively. 10%PP degraded 32.0% and the silicone control remained relatively unchanged.