Exploring the effect of higher loading of short carbon fibers on mechanical and physico - mechanical characterization of polyamide66 and polytetrafluroethylene blend composites

The influence of increased short carbon fiber (SCF) content on the mechanical properties of polyamide-66/polytetrafluoroethylene (PA66/PTFE) blend composites was examined. An 80 wt% PA66 and 20 wt% PTFE blend served as the composite matrix. The potential of SCF as a reinforcement phase with higher loading (10, 20 and 30 wt%) on these blend composites was studied. The hybrid composites were produced via twin-screw extrusion followed by injection molding. Their mechanical performance was assessed using tensile, flexural, and impact tests. The results revealed that increasing the carbon fiber content markedly improved the mechanical properties, although a marginal reduction in impact strength was observed. It was observed that 20 wt% of carbon fiber exhibits the highest strength of 134, 198 and 39 MPa respectively under tension, flexure and impact loading which is 10%, 25%, 41% increase over the neat blend (PA66/PTFE). The composites with 10 wt% SCF responds with lower strength among fiber filled ones. Carbon fiber loadings exceeding 30 wt% led to a deterioration in composite strength. A consistent decline in melt flow index was observed with increasing fiber content, reaching a minimum of 9.9 g/10 min at the highest SCF loading. The heat deflection temperature [HDT] exhibited an increase from 210.8 °C to 256 °C at 0.45 MPa and from 62.98 °C to 233.6 °C at 1.8 MPa across the investigated fiber concentrations. Conversely, the VICAT softening temperature remained unchanged with increased fiber addition. SEM examination of fractured surfaces identified fiber fracture, fiber bending, and matrix deformation as the dominant failure mechanisms.