ENTANGLEMENT IN BLENDS OF MONODISPERSE STAR AND LINEAR POLYSTYRENES .1. DILUTE BLENDS

Viscoelastic properties of binary blends composed of narrow molecular weight distribution (MWD) 4-arm star polystyrenes (2-chain) of molecular weight (MW) M//2 and narrow MWD linear polystyrenes (1-chain) of M//1 were examined and compared with binary blends of narrow MWD linear polystyrenes of M//2 and M//1. In these blends the volume fraction phi //2 of the 2-chain was kept small so that the 2-chains were entangling only with the matrix 1-chains but not with themselves. When the MW of the components of these dilute blends were such that M//c less than M//1 VM LS TH M//2, with M//c being the characteristic MW, the star 2-chain exhibited Rouse-Ham-like relaxation modes with the (weight average) relaxation time proportional to phi //2**0M//1**3M//2**2 and the compliance proportional to phi //2** minus **1M//1**0M//2.