The direct long-fiber reinforced thermoplastic (D-LFT) process is a streamlined material processing technique which includes various types of equipment. It is imperative to understand how the process and its operating conditions affect degradation and thermal properties of the processed material for industry applications. This study investigates effects of process stages, extruder temperature, and screw speed on molecular weight and thermal properties of glass fiber reinforced polyamide 6 (PA6) composites throughout the D-LFT process. Viscosity number (VN) measurements, thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) analyses were performed on collected samples. In conclusion, it was found that thermo-oxidative degradation is the main degradation mechanism of the glass fiber reinforced PA6 composites during the D-LFT process. Therefore, minimizing temperature and residence time of the extruders as well as exposure time of plastificate to atmospheric conditions along the conveyer is an effective way to minimize degradation of PA6
