Enhancement of the mechanical properties of polylactic acid/basalt fiber composites via in-situ assembling silica nanospheres on the interface

A valid strategy to tailor the properties of polylactic acid for more extensive applications was introducing filler. In this work, basalt fiber assembled with in-situ SiO₂ nanoparticles on the surface was successfully prepared via hydrothermal method and it was further treated with coupling agent KH-550 to improve interfacial interaction between polylactic acid (PLA) and basalt fibers (BF). It was demonstrated that the introduction of BFS could increase the crystallization of PLA and resulted in forming trans-crystallization based on TG and DSC results. The tensile strength of PLA/BF composites raised from 39 MPa to 62.5 MPa with increasing the fiber loading from 1 wt% to 10 wt%. Furthermore, the interfacial interaction could be effectively improved by assembling SiO₂ (especially with 250 nm in diameter) on BF surface to build mechanical locking, which could keep the PLA matrix in place during the mechanical deformation with the tensile strength value raised from 62.5 MPa to 74.0 MPa. It is noticeable that the impact and flexural properties were effectively increased with the incorporation of in-situ SiO₂ nanoparticles. The further KH-550 treatment made a positive impact as well. For instance, the impact strength and flexural strength of the sample with SiO₂ and KH-550 modification were improved to 22.49 kJ/m² and 146.83 MPa and it enhanced about 42.16% and 41.04% than those of neat PLA, respectively. Therefore, an efficient enhancement of mechanical performance was achieved and this concept of assembling in-situ SiO₂ on silica-based fiber as a modifier was a novel and simple path to design the interfacial construction and properties of the polymer composites.