凝聚条件对聚甲基丙烯酸甲酯薄膜银纹化现象的影响

<正> 当玻璃态聚合物受张力作用时,常可以观察到银纹形成,它是聚合物材料内部断裂的先兆,银纹是垂直于拉伸方向的平面缺陷,与正常裂纹不同,银纹的质量不是零,而是由沿拉伸方向排列的高度应变的微纤及孔穴组成,银纹的典型尺寸约为长100μm,宽1—2μm,微纤的直径约5—15nm,微纤的总体积分数约占20—50％,微纤能支撑负荷,因此银纹在控制聚合物屈服以后的力学行为中的作用一直是个重要的研究领域。近年来从聚合物分子缠结网对银纹生长,微纤断裂及银纹稳定性的影响方面做了一些有意义的工作。

EFFECT OF CONDENSED CONDITIONS ON CRAZING FOR CAST FILM OF POLY (METHYL METHACRYLATE)

Thin films of Poly(methyl methacrylate) (PMMA) were prepared by casting from dilute solutions. Methylene chloride, chloroform and benzene were used as solvent respectively. These films were annealed at 40 ℃ or 70 ℃. When rectangular specimens were drawn at a slow strain rate, the tensile strain for crazing εc and for specimen breakdown e?was recorded. The results show that for these films their εc , εb and the craze fibril stability which was defined as εb- εc , depends strongly on the kind of solvent and annealing temperature.