Effect of annealing on tensile properties of carbon fiber reinforced PA 6 manufactured by fused deposition modeling

Development of fiber reinforced filaments for fused deposition modeling - FDM shifted this technology application towards load carrying applications. For polymer materials reinforced with carbon fibers, it is important to carry out annealing of printed products to improve the mechanical properties. In this paper ANOVA approach was used to evaluate the effect of temperature and time of the annealing treatment of PA 6 filament reinforced with short carbon fibers (PA 6 - CF). Results indicate that higher temperatures (between 110 °C – 170 °C) result in better effects on tensile properties while duration of the annealing effect was neglible in most cases. An increase of up to 16.7% in tensile strength and up to 35% in tensile modulus can be achieved with proper annealing parameters. In some cases, annealing results in a decrease in tensile strain at break up to 35%. The p-values ​​for tensile strength, strain and modulus are 0.0038, 0.0054, 0.0168, respectively, which indicates that the selected model of the influence of annealing parameters is significant because the p-value must be less than 0.05. The highest improvement in tensile strength and modulus was observed at a temperature of 170 °C, but this temperature is close to the softening temperature of PA 6 - CF, which is approximately 180 °C before annealing, which risks deformation of products.