NOVEL FUNCTIONAL POLYMERS - POLY(DIMETHYLSILOXANE)POLYAMIDE MULTIBLOCK COPOLYMER .4. GAS-PERMEABILITY AND THERMOMECHANICAL PROPERTIES OF ARAMID-SILICONE RESINS

Poly(dimethylsiloxane) (PDMS) and aromatic polyamide (aramid) multiblo ck copolymers (PASs) ranging from 26 wt % to 75 wt % in PDMS content w ere prepared and east into transparent, ductile, and elastomeric films from N,N'-dimethylacetamide solutions. The gas permeation properties and dynamic thermomechanical properties of the PAS films were investig ated. It was found that the PASs containing < 75 wt % of PDMS had two- phase morphologies due to the great difference between the solubility parameters of the two components, in spite of the relatively low molec ular weight of each segment. PASs containing greater than or equal to 35 wt % of PDMS showed the PDMS continuous phase and interfacial mixin g occurred clearly between the two phases at the higher PDMS contents. PAS containing greater than or equal to 53 wt % of PDMS showed high e nough gas permeability compared with conventional silicone rubbers. Th e gas permeation properties can be well predicted by the PDMS contribu tion to the continuous phase rather than by the modulus behaviors alon e. (C) 1996 John Wiley & Sons, Inc.