Effect of Temperature on the Mechanical Properties and Polymerization Kinetics of Polyamide-6 Composites.

This work reports the preparation of carbon fiber reinforced thermoplastic composites via the in situ anionic ring opening polymerization of ε-caprolactam. Vacuum assisted resin transfer molding was used to fabricate polyamide-6/carbon fiber composites at different molding temperatures. As a result, the higher polymerization of ε-caprolactam was observed with the condition at 140 °C for satisfactory impregnation. Regarding molding temperature, the physical properties of polyamide-6/carbon fiber were observed that the bending and impact strengths at 140 °C were higher than those to at other molding temperatures. The polymerization kinetics of polyamide-6 was analyzed using differential scanning calorimetry by experimentally acquiring kinetic parameters according to model fitting approaches. Polymerization and crystallization, which occur simultaneously throughout the whole process, were separated using Gaussian and Maxwell-Boltzmann distributions to study polymerization kinetics. The result of the developed model was in good agreement with the experimental data for the presented first order autocatalytic reaction model.

Effect of filler content on bending properties of dental composites: numerical simulation with the use of the finite-element method.

The purpose of this work is to investigate the influence of filler content on the bending properties of dental composites by use of the finite-element method (FEM). The proposed numerical model was constructed from isotropic shell elements representing silica filler, and isotropic beam elements representing the remaining matrix resin. The proposed model was applied to failure analysis under three-point bending conditions. The validity of applying the numerical model to the failure progression analysis of composites was checked through comparison with experimental results. The results show that, in both the analytical and experimental results, the bending properties, such as maximum bending stress and bending modulus, increase with filler content. Also, the proposed method of failure progression analysis could better simulate the failure process of composites under three-point bending conditions. In addition, close agreement between the analytical and experimental results was confirmed. The above results indicate that the proposed numerical model is effective for evaluating the bending properties of dental filler composites of any content range.