Study On The Interface Crystallization Morphology Of Glass Fibre/Polypropylene Composite

Fibers, such as glass fibers and PET fibers, play a role in the nucleation of semi-crystalline polymers, inducing their crystallization and typically forming a transcrystallinity layer. The property for the composite made of fibers and thermoplastic polymers depends enormously on the forms of crystallization of the polymer matrix, but that glass fibers lack active groups on their surface leads to the low interface strength in the process of combining glass fibers and the matrix resin, and weak interlaminar shear strength, finally affecting the functions of the mechanical properties of composite materials, which restrains, in a certain degree, the application of this composite material. Similarly, that glass fibers reinforce the macro-mechanical properties of the polymer composites is also dependent on the forms and patterns of micro-crystallization of the composite materials. Therefore, the study of glass fibers'influences on the crystallization of composites is important for optimization of the mechanical properties of blended composite materials.This dissertation, by adopting various methods to carry out surface treatment for glass fibers and modification of polypropylene matrix, attempts to improve interfacial bond strength between glass fibers and polypropylene matrix.With differential scanning calorimeter (DSC), it studies non-isothermal crystallization characteristics of different ways of surface treatment for glass fibers and polypropylene composites, and investigates the cooling rate's influence on the functions of non-isothermal crystallization of the glass fibers/polypropylene composites. Furthermore, the dissertation makes use of PLM to observe the influences of different surface treatments for glass fibers and modified polypropylene upon isothermal crystallization behavior and crystalline structure of glass fibers and polypropylene composites. Such conclusions are drawn from this dissertation:(1)By using polarized light microscopy, it is directly observe that glass fiber has a good crystalline nucleation function on polypropylene, in particular, when the fiber glass's surface have been treated by coupling agent (KH550) and the matrix modified by Maleic anhydride, it induce the PP grow around the glass fiber, and the PP was induced to form transcrystallinity around the glass fiber.(2) With the increase of cooling rate, glass fiber/polypropylene composites exothermic crystallization peak shape becomes wider, and gradually move toward the lower temperature.(3) The nature of glass fiber/polypropylene composite system bonding has a significant impact on the formation of transcrystallinity, when the interface is the simple combination of the physical nature, the formation of transcrystalline is difficult, otherwise, a very solid chemical bonds occurs on the interface, it it easy to find the transcrystallinity layer.(4)Crystallization temperature has significant effect on the appearance of transcrystallinity and the types of transcrystallinity, the horizontal surface of the glass required for crystal nucleation are not the same degree, only at the appropriate temperature range, when the substrate surface in the glass high degree of nucleation, and nucleation in the matrix is low, the cross grain growth can be successfully.