Biomedical Engineering Reference
In-Depth Information
Fig. 8
Mechanism proposed by Jana et al. [65]
was grafted with polyacrylamide via a radical polymerization of acrylamide
initiated from the PDMS backbone. In order to promote chemical interac-
tions, EPDM was sulfonated, and for chemical reactivity, it was modified with
maleic anhydride (MA-g-EPDM). On the one hand, for the interactive sys-
tem PDMS-g-polyacrylamide/sulfonated EPDM, dipole-dipole and hydrogen
bonding (Fig. 9) were identified by the FT-IR shifts of the carbonyl and amide
stretching bands. It was observed that elongation at break was lower and the
tensile strength was higher in this system than in the blend of the unmodi-
fied homopolymers. According to the authors, the improved ageing behaviour
and thermal stability are due to the strong intermolecular forces. On the other
hand,forthereactivePDMS-g-polyacrylamide/MA-g-EPDMsystem,asimi-
lar analysis showed the same tendencies that is to say a higher tensile strength
and a lower elongation at break of the modified blend, and a much better re-
tention of the properties vs. ageing and thermal stability. The use of a radical
process to graft silicone has also been patented for fluoroelastomers/silicone
blends [68, 69].
