Reptation and constraint release

Abstract The reptation and constraint release models are discussed by considering three recent experimental examples: (1) the diffusion of hydrogenated polybutadiene in matrices of molecular weights raning between 1 ⩽ Mw / Me ⩽ 253; (2) the diffusion of polystyrene (PS) chains in matrices of star branched PS; (3) the diffusion of very long PS chains in chemically cross-linked PS-networks. It is concluded that the reptation and constraint release models are applicable, but ‘constraint release’ should be understood in a wider sense allowing for non-reptative removal of barriers to lateral chain motion. The analysis of the third example proves that lateral modes of motion have a negligible inf…