Investigation of I-poss adition in hybrid filler reinforced polyphenylene matrix composites: Mechanical, thermal and thermomechanical properties

Polyphenylene sulfide (PPS) is extensively used, particularly in the automotive industry, due to its high dimensional stability, robust mechanical properties, non-flammability, high temperature, and chemical resistance. However, PPS is inherently brittle with low impact strength and elongation. Therefore, fibers and particles are commonly employed as reinforcing polymers. Composite specimens were fabricated by incorporating short carbon fibers (CFs), pumice particles, and a hybrid of both into the PPS polymer. Three-point bending, DSC, and DMA tests were conducted on the specimens to evaluate changes in mechanical and thermal properties. Experimental results indicated that pumice reinforcement marginally reduces the strength of pure PPS; however, I-POSS reinforcement partially recovers this reduction. The beneficial effect of I-POSS was more pronounced in hybrid composites, which exhibited strength comparable to short CF-reinforced composites. The strength of hybrid composite samples increased from 126 MPa to 143 MPa with the addition of I-POSS. All composite samples exhibited a more rigid character compared to pure polymer, resulting in increased elastic modulus and decreased elongation at break. DSC results revealed that the reinforcing materials prevented the crystallization of PPS, while the addition of I-POSS had no significant effect on thermal properties. Consequently, the study demonstrated that while low-cost composites with pumice can be produced with some loss of strength, CF/pumice hybrid composites achieve equivalent strength to CF-reinforced composites with the addition of I-POSS. This suggests that the homogeneous distribution of pumice particles in the matrix, facilitated by I-POSS, enables the production of economically viable composites with comparable strength to those reinforced solely with CF.