RIGID-CHAIN POLYESTERS GRAFTED WITH FLEXIBLE-CHAIN VINYL-POLYMERS

The concept of ''molecular reinforcement'' has been advanced, in the l ast decade, as an alternative to conventional fibre reinforcement of t hermoplastics: In blends with normal (flexible-chain) thermoplastics, rigid chains of main-chain LC polymers (PLC) can act as strengthening fibres on the molecular scale. However, the rigid PLC chains must be w ell dispersed which is improbable since PLC and normal polymers are us ually incompatible. A related concept is ''micellar reinforcement'': G raft copolymers made of a rigid-chain PLC backbone and flexible-chain grafts can form a microphase morphology of cylindric micelles where th e PLC chains act as reinforcing fibres on a micellar scale. Such rigid -flexible graft copolymers are discussed in this study. They were pepa red from a polyester of terephthaloyl, dihexoxyterephthaloyl and pheny lhydroquinone moieties with special comonomer units carrying a double bond onto which styrene was grafted via radical copolymerisation. Graf ting occurred with high efficiency, leading to products with the desir ed morphology of cyclindric micelles.