Abstract
Both hot-mold and cold-mold compression molding of unidirectional glass fiber/polyethylene terephthalate (GF/PET) commingled yams were performed. The influences of processing parameters on the fiber distribution and matrix flow were investigated using macro and micro observations. An impregnation mechanism is proposed. The experimental results show the importance of selecting optimum processing parameters. Using proper temperature and keeping the matrix viscosity low benefits the fiber reinforcement impregnation. The pressure gradient should be sufficiently great to drive the matrix into the fiber reinforcement. However, if the applied pressure is too high, more matrix will be squeezed out with increased holding time, and the fiber deformation is in doubt. Therefore, an optimum processing window should be found in order to attain high-quality composites.