Blends Containing Tetramethyl Bisphenol-A Polycarbonate. 1. Styrenic Polymers

摘要

The phase behaviour of blends of tetramethyl bisphenol-A polycarbonate, (MPC), with styrene copolymers and substituted styrene homopolymers was examined using differential scanning calorimeter and optical indication of phase separation on heating, i.e. lower critical solution temperature, (LCST), behaviour. MPC was found to be miscible with styrene/acrylonitrile copolymers, (SAN), having an Acylonitrile content smaller than 13%, with a styrene/maleic anhydride copolymer, (SMA), having an maleic anhydride content equal to 8% and with oligomeric styrene/allyl alcohol copolymers, (SAA), having an allyl alcohol content less than 19.1%. MPC was also found to be miscible with an oligomeric poly(alpha-methyl styrene), P alpha MS, and a copolymer of alpha-methyl styrene/acrylonitrile, P alpha MSAN. Some of the mixtures showed LCST behaviour and based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. It appears that small amounts of AN or MA in the copolymers apparently increases the strength of interactions relative to those observed in polystyrene blends with MPC, whereas the the inclusion of a methyl group in the styrene repeat unit has the opposite effect. The phase behaviour of MPC with styrene based copolymers appears to be influenced by intrachain repulsion between styrene and comonomer units. MPC was found to undergo thermal and solvent induced crystallization when blends were cast from tetrahydrofuran and toluene solutions, but no crystallinity was observed when methylene chloride was used as the solvent.