TOUGHENED POLYESTER NETWORKS

Mixtures of unsaturated polyesterstyrene and liquid epoxy resin, each with its own curative, have been found to yield transparent crosslinke d material when a reactive liquid rubber (ATBN) is added. The properti es of this network vary in a systematic fashion with rubber content. A s much as a tenfold increase in critical energy release rate, from 59 N/m to 618 N/m, and a six-fold increase in strain-to-failure, from 1.6 % to 11.2%, have been measured. The final matrix is a two phase materi al comprised of pure polyester/epoxy domains and a rubber modified pol yester/epoxy domain. Transmission electron micrographs show the rubber to be uniformly distributed throughout the matrix with domain sizes o f the order of a few hundred angstrom units. This morphology is also s upported by SEM and DMA data.