Modifying the properties of polyamide 6 with high-performance environmentally friendly nano- and microsized reinforcing materials

In this study, we investigated the morphological and mechanical properties of hybrid composites with a polyamide 6 (PA6) matrix and reinforced with basalt fibers (BFs) and halloysite nanotubes (HNTs). The presence of reinforcing materials fundamentally changed the behavior of the molecules, which was morphologically manifested in the change in the ratio of the rigid and the mobile amorphous phase. The x-ray diffraction and transmission electron microscopic images showed the crystal nucleating effect of the halloysite nanotubes. Based on these, we concluded that around the basalt fibers, an interphase is formed, while around the nanoparticles, a two-layer interphase is created, the inner layer of which is semicrystalline, while the outer layer is rigid amorphous (RA). The nanoparticles are surrounded by a semicrystalline interphase, which is surrounded by an RA interphase. This overlaps with the interphase of the basalt fibers, therefore the halloysite nanotubes can effectively help the stress transfer from the matrix to the basalt fibers. The mechanical properties of the samples also reflected this: the hybrid composites had a significantly higher tensile modulus, tensile strength, and an unchanged elongation at break compared to the composite reinforced with only basalt fiber.Highlights Environmentally friendly polyamide 6 matrix hybrid composites were prepared. Uniform distribution of halloysite nanotubes was achieved. Enhanced mechanical properties were observed for hybrid composites. Halloysite nanotubes aid stress transfer from matrix to basalt fibers. Halloysite nanotubes act as crystalline nucleating agents. Enhanced stress transfer between the basalt fiber and the matrix via the overlapping interphases. image