高分子链的去拥挤转变及低温流动

简述了拥挤理论的基本原理,运用拥挤理论来说明高分子链间弱相互作用对高分子链所处的状态的影响,特别是对高分子玻璃化转变的影响.在实验中,采用固体核磁共振方法探测高分子的链间邻近度,并比较了不同链间邻近度的高分子样品在玻璃化转变温度以下的压力诱导流行行为,发现即使测试温度比高分子玻璃化转变温度低132℃,高分子链在压力下依...

UNJAMMING TRANSITION AND COLD FLOW OF POLYMER CHAINS

Jamming occurs when a system develops a yield stress——behaves as a solid——in a disordered state,and it governs the transition behavior of foams,emulsions,colloidal suspensions,pastes,granular media and molecular glasses.For polymer glasses,when the interchain proximity was enlarged,the weak interaction between polymer chains was decreased,and these loosely packed chains can flow solely by applying pressure at temperature 132 degrees below their calorimetric glass transition temperature,Tg,which means Tg decreased to a great extent in this progress.This phenomenon is connected to the concept "jamming",which suggests the generality of an idea that one can take polymer glasses through solid-to-liquid transition by thermalization,through temperature,or by a load.It is expected within the jamming picture that we could process polymers at lower temperature or even at room temperature.