Thermal properties of carbon fiber reinforced polyamide 66 composites throughout the direct long-fiber reinforced thermoplastics process

The direct long fiber reinforced thermoplastics (D-LFT) process is a series of processes involving two twin-screw extruders, a conveyer, and a compression molding machine. This study investigates variation on thermal properties of carbon fiber reinforced polyamide 66 (PA66) composites throughout the D-LFT process. Samples were taken from five different locations along the D-LFT process and characterized using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results suggested that the thermal stability was decreased continuously up to the halfway point of the conveyer, but increased from the half conveyer to the compression molding. The degree of crystallinity was little changed throughout the process, but the crystallization half-time was increased after the half conveyer.