熔体拉伸对聚苯乙烯屈服行为影响的研究

Study on Effect of Melt Stretching on Yielding Behavior of Polystyrene

作为典型的玻璃状聚合物,聚苯乙烯在室温下通常表现出脆性。通过熔体拉伸法可以诱导聚苯乙烯在室温下发生脆韧转变。研究聚苯乙烯的脆韧转变行为和屈服行为是研究玻璃状聚合物大形变机理的重要工作之一。采用熔体拉伸法在不同的熔体拉伸应变下制备了聚苯乙烯薄膜,基于Eyring屈服活化理论计算了熔体拉伸聚苯乙烯薄膜在不同温度下的屈服活化能。结果表明,随着熔体拉伸应变的增加,薄膜的屈服应力及屈服活化能快速下降,从而赋予了聚苯乙烯在室温甚至更低的温度环境内发生拉伸屈服的能力。

As a typical glassy polymer,polystyrene usually exhibits brittle fracture at room temperature.The melt-stretching method can induce the brittle-ductile transition of polystyrene at room temperature.The study on brittle-ductile transition behavior and yielding behavior of polystyrene is one of the important works to investigate the mechanism of large deformation of glassy polymers.The pure polystyrene films with toughness at room temperature were prepared by the melt-stretching method.The yield activation energy of pre-melt stretched polystyrene films at different temperatures was calculated based on the Eyring yield activation theory.The results showed that the films yield stress and activation energy decreased rapidly with increasing melt stretching strain,which conferred the ability of polystyrene to undergo tensile yielding at room temperature or even lower temperature environments.