Entanglement Formation Near the Glass Transition Temperature
The formation and breakdown of entanglement coupling points between molecular coils plays an important role in polymer rheology. Their effect on the viscosity of solutions and on the elastic modulus of rubbery networks is well investigated. Until recently very little was known, however, on the kinetics of entanglement formation at temperatures close to the glass transition temperature (Tg) although the practical importance of chain interpenetration and entanglement coupling for good mechanical properties of thermoplastic materials, especially at long times, higher temperatures and in the presence of active environments, is generally recognized. In the last few years, however, the self-diffusion and interpenetration of chain molecules in entangled polymer systems has attracted growing attention following the development of the reptation model of longitudinal diffusional motion by De Gennes (1) and Doi and Edwards (2). Experimental studies have been carried out meanwhile concerning the kinetics (3–5) and the mechanical effects (6) of chain penetration. In this paper the mechanism of entanglement formation and resolution is further investigated by variation of the conditions of entanglement formation and by measurement of the energy necessary for the mechanical separation of the partially interdiffused networks.
KeywordsFracture Toughness Glass Transition Temperature Compact Tension Virgin Material Entanglement Formation
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