A Study on Phase Separation of PA-PDMS Composites Dependent on Molecular Weight

An opaque PA-PDMS (polyamide-polydimethylsiloxane) mu-composite and a transparent PAI (polyamidimide)-PDMS nanocomposite were produced by a sol-gel process. Molecular weight played the largest role in affecting the size of PDMS particles, and this was proven by using the same polymer (PA) with different molecular weight. Unlike the original PA, PA with lower molecular weight produced transparent PA-PDMS nanocomposites. The mechanical properties were largely affected by molecular weight; however, the thermal property was not affected as much. The Tg of the PA-PDMS composite was the same as that of PA. In the case of the PA-PDMS composite, the water-resisting quality improved greatly, and toughness was most improved when 30 wt.% DEDMS (diethoxydimethylsiloxane) and 30 wt.% coupling agent was added to the polymer, regardless of the degree of phase separation, molecular weight, and the type of polymer.