RESUMO
As environmental regulations become stricter, weight- and cost-effective fiber-reinforced polymer composites are being considered as alternative materials in the automobile industry. Rapidly impregnating resin into the reinforcing fibers is critical during liquid composite molding, and the optimization of resin impregnation is related to the cycle time and quality of the products. In this review, various resins capable of rapid impregnation, including thermoset and thermoplastic resins, are discussed for manufacturing fiber-reinforced composites used in the automobile industry, along with their advantages and disadvantages. Finally, vital factors and perspectives for developing rapidly impregnated resin-based fiber-reinforced composites for automobile applications are discussed.
RESUMO
In this study, Y2O3/TiO2-loaded polyester fabric was prepared to improve the catalytic activity of the TiO2 and to increase its reuse efficiency. The samples were systematically characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (FT-IR). Furthermore, the degradation performance of methyl orange in the presence of simulated visible light irradiation was also investigated. The results showed that the TiO2 in the Y2O3/TiO2 composite photocatalyst was suitably anatase. In addition, Y2O3/TiO2-loaded polyester fabric had higher photocatalytic performance than that of pure polyester fabric under visible light and the degradation rate reached 83% after 120 min of light exposure but remained above 50% after repeated exposure (three times). Compared to the pure polyester fabric, Y2O3/TiO2-loaded polyester fabric had self-cleaning effects in methyl blue and soy sauce solutions under visible light.
RESUMO
Graphene oxide (GO) and multiwalled carbon nanotubes with silver particles (MWNT-Ag) of different concentrations were used as nanofillers to prepare poly(lactic acid) (PLA) nanoparticle films through the solvent casting method. In this study, the effects of nanoparticles on the crystallization behavior, relationships between the dispersion and electrical properties, and hydrolytic degradation behaviors were investigated for the PLA/MWNT-Ag and PLA/rGO films. Differential scanning calorimetry was used to evaluate the crystallization behaviors of the PLA/MWNT-Ag and PLA/reduced GO (rGO) films. Electron probe microanalysis was performed to characterize the dispersion of MWNT-Ag, and X-ray diffraction and Raman spectroscopy were used to determine the degree of dispersion of rGO in the PLA matrix. The results showed that nanoparticles enhanced the crystallization kinetics of PLA as well as the hydrolytic degradation rate. From the measurement of electrical properties, the electrical conductivity of PLA/MWNT-Ag 1.0 wt% was much higher than that of the pure PLA and PLA/rGO films, showing that MANT and Ag nanoparticles contribute greatly to enhancing the electrical conductivity of the PLA/MWNT-Ag films.
RESUMO
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.
RESUMO
Composites using dicyclopentadiene (DCPD) as a matrix have gained significant popularity owing to their excellent impact and chemical corrosion resistance. In the present study, experiments addressing the impact behavior of glass-fiber-reinforced DCPD were conducted to quantitatively evaluate its impact properties. The glass-fiber-reinforced polydicyclopentadiene composite utilized in impact tests was manufactured using structural reaction injection molding (S-RIM) because of its fast curing characteristics and low viscosity. The impact properties of the glass-fiber-reinforced DCPD (GF/DCPD) were quantitatively evaluated by varying its fiber content and decelerator solution. The impact properties of neat DCPD and GF/DCPD composites were examined with different amounts of decelerator solution under various temperatures from room temperature to cryogenic temperature to observe the ductile-to-brittle transition temperature (DBTT). With an increase in the fiber weight fraction of the GF/DCPD composite, the effect of the DBTT significantly decreased. However, the decreasing rate retarded as the weight fraction of the GF increased. The decreased DBTT with the addition of GF in the GF/DCPD can be attributed to the differences in the thermal expansion ratio and the interfacial force between neat DCPD and the fiber. A fractograph analysis demonstrates that the effect of the brittle (smooth) surface resulted in a lower impact absorbed energy when the temperature decreased, along with the increased amount of the decelerator.
