Effect of processing conditions on morphology and mechanical damage in glass-reinforced polypropylene composite

Abstract

This study aims to analyze the effect of processing parameters, particularly the cooling rate, on the morphology and mechanical properties of reinforced glass fiber polypropylene (GF-PP) films. To achieve the objective, a multi-scale analysis was performed to study the different morphology of neat PP and reinforced PP films obtained by controlling the thermal condition during the fabrication process. Films of PP with a thickness of about 100 μm have been prepared to observe the crystalline microstructure's formation and follow its kinetics on the scale of the spherulites. The same procedure was followed using a single glass fiber to obtain the mono-composite film of PP by controlling the interface/interphase between the fiber and the matrix. Moreover, the dependence of the damage mechanisms on the spherulite diameters and the mechanical test conditions was established. The deformation mechanisms (intra and inter-spherulitic damage) were analyzed qualitatively and quantitatively according to the controlled morphologies produced for the polymer and the composite, especially at the level of the transcrystalline phase. The results confirm that the processing parameters affect not only the width of the transcrystalline phase but also the morphology of the fiber-matrix interface. Furthermore, increasing the thickness of the transcrystalline phase exhibited remarkably higher interfacial shear strength, as demonstrated by the single fiber fragmentation test.