The concept of cohesional entanglement

Abstract

A concept of cohesional entanglement through local nematic interaction of neighboring chain segments has been introduced in addition to the usual topological entanglement of chains. As topological entanglement is important to properties of the polymer in the rubbery and flowing states at temperatures well above its Tg, the cohesional entanglement is important to properties at temperatures around and below Tg. Evidences for the existence of cohesional entanglements are presented. From the point of view of cohesional entanglement the DSC curves of glass transition and the effect of sub‐Tg annealing are discussed. Finally the stress peak on yielding during uni‐axial drawing, rejuvenation of sub‐Tg annealed polymer by drawing and anti‐plasticization of plastics are discussed based on the concept of cohesional entanglement.

Analysis of the Adequacy of the Representation of Entanglement Effects by Chain Loops

“…[37] He followed a completely different approach than the one used in this work, and he was not as incisive and clear in his conclusions as the results of Figure 2 and 4 demonstrate. He evaluated the amount of coil interpenetration as a function of the polymer molar mass from the coil and polymer melt densities.…”

The Study of Stress-Yielding of Aged Atactic Polystyrene (a-PS) by Differential Scanning Calorimetry

“…This structure is believed to be the result of local molecular packing arrangements upon annealing, which later was termed as cohesional entanglements (CE for short), a kind of binary or multiple inter-chain cohesion (attractive interaction) with local parallel alignment of neighboring chain segments. [10,11] A similar idea that is in complete accord with the concept of CE was first raised by Raha and Bowden, by the name of 'cohesional points', to explain the strain behavior of rubber at yielding. [12] In order to achieve evidence for the unlocking of CE as a mechanism of yielding for glassy polymers, DSC was used to monitor in detail the process of stretch of aged a-PS.…”

Influence of water on the physical aging of poly(ethylene terephtalate)

“…Many authors are postulating the formation of regions in the glassy state in which interchain packing occurs. Recently, Qian (17)(18)(19)(20) has proposed the concept of interchain cohesional entanglements of neighbouring chain segments in the glassy state.…”