MODEL NETWORKS.

Abstract

This review paper is concerned with model networks which can be considered as a new class of tridimensional polymeric material, with elastic chains of known and rather constant length, and branch points of almost constant functionality, with few defects, and of very satisfactory homogeneity. By combination of structural determinations and of swelling and deformation measurements it was shown that the existing theories of rubber elasticity are applicable, even though some ambiguity still exists as to what concerns the value and the meaning of the memory term. The model networks can be synthesized with linear polymer chains trapped in the tridimensional matarix. If the chains are chosen long enough they cannot diffuse out of the network, even when it is swollen in good solvents. The most important result obtained on the structure of model networks is the existence of a rather well-defined correlation distance between first neighbor crosslinks. It is concluded that model networks, synthesized by endlinking processes, contain few structural defects and are close to ideality. Spring-suspended bead models seem to fit adequately with the structural data obtained on labeled networks and with the swelling and uniaxial deformation behavior of these networks.