"Various chemical and physical aspects of high lipid absorption by medical grade silicone rubber and the dynamic mechanical properties of lipid-rubber systems were studied in order to provide an insight into the problem of 'variance' of these materials when subjected to 'in vitro' and 'in vivo' environments. Wide variations of post cure procedures of the silicone rubber were studied. Different post cures did not appreciably affect the mechanical properties of the silicone rubber. Mass transfer studies demonstrated that the diffusion of linolenic acid into a silicone rubber slab is a purely physical diffusion process (D = 3.2 x 10-3 cm2/min). Pure diffusion did not account for the high lipid uptake of silicone rubbers which had been exposed to a human environment. Several 'in vitro' tests utilizing a metal salt (FeCl3) as a catalyst inside the silicone rubber produced a 21% lipid weight gain in 10 days.
A possible mechanism for high lipid uptake of the silicone rubber is proposed. The mechanism is consistent with reported analytical findings of 'in vivo' lipid tests. Dynamic mechanical (viscoelastic) property studies indicated that silicone rubbers which had high lipid uptakes were deteriorated. At body temperature the modulus of the lipid-rubber system (35% lipid uptake) was 0.34 x 108 dyne/cm2 compared to 1.0 x 108 dyne/cm2 for new silicone rubber.
The findings of this investigation will serve as a foundation for further study directed toward the elimination of high lipid uptake when silicone rubber is subjected to 'in vivo' environments "--Abstract, page iii.
Mayhan, Kenneth G.
Bertrand, Gary L.
Wellek, Robert M.
Venable, Raymond L., 1935-2008
Patterson, G. K. (Gary Kent), 1939-
Chemical and Biochemical Engineering
Ph. D. in Chemical Engineering
University of Missouri--Rolla. Graduate Center for Materials Research
University of Missouri--Rolla. Department of Chemical Engineering
National Institutes of Health (U.S.)
University of Missouri--Rolla
xi, 130 pages
© 1974 Shu Hua Wu, All rights reserved.
Dissertation - Restricted Access
Library of Congress Subject Headings
Silicone rubber -- Analysis
Viscoelasticity -- Mathematical models
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Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.http://laurel.lso.missouri.edu/record=b1067249~S5
Wu, Shu Hua, "In vitro studies of lipid uptake by medical grade silicone rubbers used for heart valve balls" (1974). Doctoral Dissertations. 282.
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