The efficiency of isocyanate coating on the basalt fibre surface for the mechanical performance of elastomeric polyurethane composites

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The influence of the isocyanate layer on fibre surface to mechanical, thermo-mechanical, processing, and morphological properties of basalt fibre (BF) reinforced elastomeric polyurethane (EPU) composites was examined by utilizing tensile test data and Shore hardness measurements, dynamic mechanical analysis (DMA), melt flow index (MFI) and scanning electron microscopy (SEM) techniques. BF was modified with an isocyanate functional group containing silane modifier. Isocyanate moieties on BF surface were confirmed via functional group analysis by infrared spectroscopy. SEM/EDX analysis was also used to visualize the sized and desized BF surfaces. Composite samples were fabricated using conventional processing methods, including extrusion and injection molding. Silane covering involving isocyanate functional group on fibre positively affected the tensile strength and tensile modulus of composites. Percent elongation of EPU showed a reduction trend with the incorporation of both sized and desized BF. The shore hardness of EPU increased by BF inclusions. According to DMA results, higher storage modulus values were obtained for surface-modified BF-filled composites compared to desized BF ones. BF additions resulted in no remarkable change in the MFI parameter of EPU. SEM images represented visual evidence for enhancement in mechanical performance by investigating better adhesion of the isocyanate layer of BF to EPU matrix concerning desized BF. The importance of surface sizing on BF surface in the case of BF-reinforced EPU composite applications was evaluated based on the compatibility of composite phases.