Effect of Polyurethane Treatment on the Interfacial and Mechanical Properties of Basalt Fiber-Reinforced Polymer Composite

Improving the interfacial bonding properties of basalt fiber-reinforced polymer (BFRP) to enhance the overall performance, keeping the existing technological flowsheet, meanwhile, fulfilling the product variety needs with a simple process are of great importance for both basalt fiber (BF) producer and its industry. In this study, polyurethane was coated as a coupling agent on the surface of BF to improve the bonding properties of BFRP interfaces, and the surface coating treatment process was also investigated. The results indicated that polyurethane treatment helped to enhance both the interfacial shear stress and the tensile properties of the BFRP; moreover, the treating process was particularly important, with the most significant improvement brought about by directly coating the surface of the original BF. SEM observation results illustrated that all samples treated with polyurethane had good interfacial adhesion between the fibers and polymeric matrix. In addition, chemical structural analysis of the BF surface based on FTIR and XPS results showed that polyurethane coating treatment could bring lots of polar functional groups to the fiber surface, especially the ones performed directly on the original BFs. Combining the experimental results and the interfacial functionary mechanisms, a discussion of the reinforcing mechanisms found that the introduction of polyurethane resulted in a mix of interfacial functionary mechanisms. In general, this work demonstrated that the approach of applying polyurethane directly on the original BF was a novel and facile concept and fulfilled the demands of both BF producers and downstream manufacturers.