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

Abstract

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.

Keywords

• thermoplastic composites
• automated fiber placement
• non-isothermal crystallization kinetics
• cooling speed
• crystallinity