Optimization Mechanism of Mechanical Properties of Basalt Fiber-Epoxy Resin Composites by Interfacially Enriched Distribution of Nano-Starch Crystals

Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength, designability, good dimensional stability and ease of large-area monolithic forming. However, the problem of interfacial bonding between the resin matrix and the fibres limits the direct use of reinforcing fibres and has become a central difficulty in the development of basalt fibre-epoxy composites. This paper proposes a solution for enhancing the strength of the fibre-resin interface using maize starch nanocrystals, which are highly yield and eco-friendly. Firstly, in this paper, corn starch nanocrystals (SNC) were prepared by hydrolysis, and were deposited on the surface of basalt fibers by electrostatic adsorption. After that, in order to maximize the modification effect of nano-starch crystals on the interface, the basalt fiber-epoxy resin composite samples were prepared by mixing in a pressureless molding method. The test results shown that the addition of basalt fibers alone led to a reduction in the strength of the sample. Deposition of 0.1 wt% SNC on the surface of basalt fibers can make the strength consistent with pure epoxy resin. When the adsorption amount of SNC reached 0.5 wt%, the tensile strength of the samples was 23.7% higher than that of pure epoxy resin. This is due to the formation of ether bond homopolymers between the SNC at the fibre-epoxy interface and the epoxy resin, which distorts the originally smooth interface, leading to increased stress concentration and the development of cracks. This enhances the binding of basalt fibers. The conclusions of this paper can provide an effective, simple, low-cost and non-polluting method of interfacial enhancement modification.