Effect of low temperature on mechanical properties and fracture behavior of 3D printed short carbon fiber reinforced polyether ether ketone composites (CF/PEEK)

This study systematically analyzes the effect of low-temperature environments on the mechanical properties and fracture behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites printed using fused deposition modeling (FDM). The mechanical properties of FDM-printed CF/PEEK composites were tested at five ambient temperatures, with liquid nitrogen's low boiling point used for cooling. A regression model predicting tensile strength was developed based on experimental results and subjected to analysis of variance and significance tests. The results showed that the tensile strength of CF/PEEK composites significantly decreased with decreasing ambient temperature. At -175 °C, the tensile strength dropped to 12.83 MPa, a decrease of 84.3% compared to 25 °C. The elastic modulus first decreased and then increased across the temperature range. Scanning electron microscopy (SEM) was used to examine the low-temperature fracture behavior. The fracture mode shifted from ductile to brittle, and the interfacial bonding between fibers and the matrix weakened, contributing to the decline in the composites' tensile properties. These findings aim to enhance the understanding of CF/PEEK composites' performance in low-temperature environments, providing insights for their application in these conditions.