Effects of extruder screw configuration on thermal properties of glass fiber reinforced polyamide 6 composites throughout the direct long-fiber reinforced thermoplastics process

This study investigates the effects of screw configuration of the second extruder on the thermal properties of glass fiber reinforced polyamide 6 (PA6) composites throughout the direct long-fiber reinforced thermoplastic (D-LFT) process. Two screw configurations, which generate low and high shear stress in composite melts, were applied to the second twin-screw extruder in the D-LFT process. Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) analyses were performed on samples taken from different locations along the D-LFT process. TGA results showed that thermal stability of the final products can be improved by decreasing shear stress in composite melts in the second extruder. Non-isothermal DSC crystallization analysis revealed no substantial changes to the material's degree of crystallinity with the variations in screw configuration. Isothermal DSC crystallization analysis also showed that the screw configurations had little effect on crystallization half-time of the final products.