Impact of basalt powder on the rheological, thermal, mechanical, and tribological properties of natural and polychloroprene rubber composites: A study on aging and filler interaction

This study investigates the effects of basalt powder (BP) as a filler in natural rubber (NR) and synthetic polychloroprene rubber (CR) composites, focusing on their structural, mechanical, and thermal properties before and after aging. The NR/BP and CR/BP composites were prepared with varying basalt content levels of 0, 5, 10, 15, 50, and 100 parts per hundred rubber (phr) and characterized accordingly. Mechanical properties such as tensile strength, Young's modulus, and abrasion resistance were evaluated, alongside thermal properties, using thermogravimetric analysis. The results showed that increasing the basalt content reduced dispersion quality and weakened the filler and matrix interaction, decreasing tensile strength and Young's modulus. The reduction in tensile strength is substantial, with a decrease of 71.7% in NR/BP composites and 64.1% in CR/BP composites at maximum additive ratios. Aging significantly improved the tensile strength and modulus of the materials, which are attributed to an increased crosslink density and the transformation of polysulfide bonds into disulfide bonds. Shore A hardness increased with basalt content, reaching 60.3 for NR/BP and 74.1 for CR/BP at 100 phr, while abrasion resistance decreased, with abrasion loss rising by 130% and 88% for NR/BP and CR/BP composites, respectively. Scanning electron microscopy (SEM) analysis revealed increased surface roughness and filler aggregation at higher basalt contents, contributing to reduced mechanical performance. Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX) analyses confirmed the presence and dispersion of basalt powder within the composites.