自动铺放成型热塑性复合材料的非等温结晶动力学研究

利用差示扫描量热仪结合Avrami方程研究玻璃纤维增强聚丙烯复合材料自动铺放成型过程非等温结晶动力学,推导非等温结晶动力学模型,并通过构建冷压辊下方铺层的冷却模型,将结晶动力学模型和传热模型相结合,设定自动铺放成型过程中的冷却条件,探讨冷却速率及冷却时间对基体材料结晶行为的影响,求解出不同冷却速率下的最大铺放速率。研究结果表明:铺层树脂基体的结晶度随冷却速率的增大而依次减小;随着冷却速率的提高,树脂结晶起始温度和结晶完成温度均向低温方向移动,且树脂相对结晶度随温度变化规律接近反S形曲线;自动铺放成型实验件的压缩强度及层间剪切强度随着铺层结晶度的增大基本呈增大趋势,而冲击强度与铺层结晶度的变化趋势完全相反,随着结晶度的增大,材料韧性越差。

Non-isothermal Crystallization Kinetics of Thermoplastic Composite for Automated Fiber Placement

The non-isothermal crystallization kinetics of glass fiber reinforced polypropylene for automated fiber placement was studied by differential scanning calorimetry (DSC) and Avrami equation. To investigate the influence of cooling rate and cooling time on non-isothermal crystallization behavior of matrix material and solve the maximum processing speed at different cooling speed, the non-isothermal crystallization kinetics model and the heat transfer model were derived and the cooling conditions in the process of automated fiber placement were set up. The result shows that the crystallinity of the polypropylene decreases along with the increase of cooling speed. The initial and final crystallization temperature are both moving in the direction of low temperature with the increase of cooling speed. The relative crystallinity is closed to the S type curve along with the change of temperature. The compress strength and the interlaminar shear strength are all increasing with the increase of the crystallinity, however, the impact strength is decreasing along with the increase of the crystallinity which is opposite to the compress strength and the interlaminar shear strength.