高聚物从高弹态到流体态的转变

Transition from a Rubbery Elastic State to a Fluid State of Polymer

将高聚物由高弹态转变为流体态的转变温度命名为流动温度Tf,该转变温度与高聚物分子量密切相关。在高聚物从高弹态转变为流体态的研究中,由于Tl,l的概念忽视对高聚物分子量的依赖性,因此采用Tf的概念更为合理。本文对高聚物的流动温度Tf的讨论涉及高聚物温度-形变曲线、高弹态温区、高聚物熔体剪切粘度。从高聚物凝聚态观点来看,高聚物熔体中凝聚缠结网络中的凝聚结点是分子链的局部向列相互作用使链单元间产生平行凝聚而形成的,而高聚物从高弹态到流体态的转变正是反映了高聚物熔体中凝聚缠结网络的物理交联点,即凝聚结点状态的变化。高聚物熔体可以流动,说明熔体中凝聚网络中的凝聚结点至少是可以在瞬间内打开的,升温使凝聚结点的解凝聚状态存在的时间加长,凝聚状态存在时间减短,当升高到某一温度时,在凝聚结点解凝聚状态的时间内,分子链通过内旋转使质量中心在外加力的方向上可以发生位移,此时高聚物从高弹态转变为流体态,而此时的温度就是流动温度Tf。对高聚物流体弛豫网络的研究,是一个很有前景的研究课题。

On increasing the temperature of polymer a transition from a rubbery elastic state to a fluid state could occur. The transition temperature is termed the fluid temperature of the polymer, Tr, which has direct relation with the polymer molecular weight. As one of polymer parameters, special attention to Tf should be paied for polymer processing. In researches on the transition of polymer from a rubbery elastic state to a fluid state the concept Tf would be more reasonable and more effectve than the concept Tl,l because it is neglected in the concept Tl,l that the molecular weight of polymer has effects on the transition. In this paper the fluid temperature of polymer, Tf ,is involved in the characters of polymer,such as the curve of deformation-temperature, rubbery elastic state and shear viscosity of melt. From the viewpoint of cohesional state of polymer the transition of polymer from a rubbery elastic state to a fluid state responds to destruction and construction of the cohesional entanglement network in the polymer. The relaxing network of polymer melt would be worthy to be considered as an object of studv.