偏氯乙烯-氯乙烯共聚物薄膜挤出成型中的动态结晶过程

Study on the dynamic crystalline process of VDC/VC copolymers in their film extrusion

对偏氯乙烯氯乙烯共聚物（ＶＤＣＶＣ）薄膜生产过程进行了分步模拟， 通过Ｘ 光衍射、ＤＳＣ分析， 揭示了生产环节中温度、应变、时间等对薄膜结晶的影响。实验表明， 骤冷保持了管膜的无定形状态； 在３６ ℃温水浴中停留时间的增加使晶粒尺寸增长； 随拉伸速度增加， 初期结晶速度加快， 但在结晶后期达到的结晶度变化不大；当拉伸比大于３ 时， 应变诱导结晶形成较快， 拉伸结晶比等温结晶形成的晶粒尺寸小得多； 正常生产的薄膜在室温下存放晶粒会缓慢增长， 结晶度略有提高。

The manufacturing process for VDC/VC polyvinylidene chloride film was simulated step by step to analyze the effect of processing parameters, including temperature, strain and time, on the crystallization. Some analyzing techniques like X ray diffraction and DSC were applied to observing the crystal structure of samples. The experimental results have shown that quenched operation in a cold water bath made the tubular extrudate remain in the fully amorphous state, which was in the nucleating period; the crystalline size increased with the increase in retention time of the tube in a warm water bath(36?℃); although the initial crystallizing velocity was higher at higher extension rate, the final crystallinities reached in the samples were approximate; when the extension rate was greater than 3, the strain induced crystallization proceeded relatively fast and the crystalline size formed by extension crystallization was much smaller than that by isothermal process; the crystalline size in VDC/VC film would increase slowly and the crystallinity would rise slightly when the VDC/VC film obtained in production was stored at room temperature.