No abstract

Hybrid composites of polycarbonate (PC) reinforced with short glass fibers (GF) and short carbon fibers (CF) were prepared by twin-screw extrusion and injection molding techniques. Composites were produced in different ratios of GF and CF by maintaining the total fiber loading at 40 wt%. The mechanical properties such as tensile, flexural strength, and impact of these composites were investigated. It was noted that an increase in GF content led to a higher strength of the hybrid composites as compared to CF. Morphological analysis by using scanning electron microscope reveals that CF had poor fiber-matrix interactions with PC, which brought about the decrement of stress-transfer efficiency. A poor fiber-matrix interaction is believed to be the main cause of the lower strength enhancement by CF than expected. Heat deflection temperatures of composites increased with the increment of GF content. From dynamic mechanical thermal analysis, high-storage modulus is observed at the temperature below Tg. Meanwhile, it was observed that surface and volume electrical resistivity decreased by increasing the CF content owing to its conductivity.

In this research, polycarbonate (PC) composites with short glass fiber (SGF) and short carbon fiber (SCF) hybrid fiber reinforcements were compounded by single screw extruder and specimens were prepared by injection molding machine. This article aims to investigate the mechanical properties of PC hybrid composites, by means of the experimental and the theoretical methods. The composites were subjected to tensile test. Experimental results showed the improvements in tensile strength and modulus by increasing the SCF content of the hybrid composite. The theoretical tensile strength was predicted based on Kelly-Tyson model and rule of hybrid mixture. Kelly-Tyson model showed to be a good approximation to predict the tensile strength of composite. When the SCF was replaced by milled carbon fiber (MCF) to form a PC/SGF/MCF hybrid system, poorer mechanical properties are reported due to the weaker interfacial adhesion between MCF and PC, as proven by the scanning electron microscopy. POLYM. COMPOS., 37:1238-1248,

The objective of this research was to study the effects of polytetrafluoroethylene (PTFE) as a solid lubricant on the mechanical, electrical, and tribological properties of carbon fiber (CF)‐reinforced polycarbonate (PC) composites. Samples were prepared by means of single‐screw extrusion and injection molding processes. The mechanical tests included tensile, flexural, and failing weight impact tests, while the electrical tests consisted of surface and volume resistivity tests. The tribological testing was conducted under dry sliding conditions using pin‐on‐disk configuration. The results showed that the addition of CF managed to significantly reduce the electrical resistivity as the CF loading approached 10–15 wt%. The addition of PTFE managed to reduce the resistivity of the composite, that is, from 4.51 to 0.53 × 10 (Ωcm). The incorporation of 15 wt%. CF resulted with an increase of 45% in tensile strength and 51.5% in flexural strength, while the addition of PTFE had a negative impact on both properties. It was shown that PTFE was able to reduce the friction coefficient, μ and wear rate, K up to 0.257 and 6.35 × 106 (mm3/Nm), respectively, which can be attributed to the excellent abilities of PTFE to form transfer film. The composite consisting of 15 wt% CF and 10 wt%. PTFE showed highest improvement in term of electrical resistivity, and is deemed the most suitable composition for this study. Scanning electron microscopy was also carried out to further elucidate the fracture and wear mechanism of the PC/CF/PTFE composites.