Recycle poly(ethylene terphthalate) (RPET) was compounded with talc, glass bead and PEG in twin screw extruder with different cooling systems of hot air cooling and water cooling processes. The air cooling system allowed slow cooling and higher crystallized of RPET in the compounds, which resulting in higher crystllinity in the compounds as compared to the water cooling. Moisture content of the compounds decreased when increasing crystallinity. It is interesting to note that tensile properties of the RPET compunds would enhance when incorporated with talc filler and when lower moisture content values in the RPET compounds.

In this research, recycled-polyethylene terephthalate (PET) and polycarbonate (RPET/PC) blends fabricated by vented barrel injection molding were presented to better understand the effect of devolatilization during molding process. The effect of dried pellets, non-dried pellets, using an opened-vented hole, and using a closed-vented hole on the miscibility, morphology, thermal properties and mechanical properties of RPET/PC blends was investigated. The results indicated that no drying decreases dispersion, thermal properties, and mechanical properties of RPET/PC blends due to hydrolysis degradation of recycled-PET during the injection molding process. Using the venting system with non-dried RPET/PC blends partially improves dispersion, thermal properties and molecular weight of RPET/PC blends processed without drying, giving results that are similar to those processed with drying. Regarding the flexural properties, using the venting system without drying prevents the flexural properties from decreasing in RPET/PC blends, if the amount of RPET is less than 75 wt%. When the content of RPET is over 75 wt%, using the venting system does not eliminate the decrease in flexural properties of RPET/PC blends. When the venting system is applied to non-dried RPET, despite hydrolysis degradation of RPET not being completely eliminated, the damaging effects are nonetheless reduced compared with those samples processed without the venting system. As a result, vented barrel injection molding hardly prevents non-dried RPET/PC blends from having reduced flexural properties when the content of RPET is greater than 75 wt%.

Abstract Improving the applicability of polyethylene terephthalate (PET) by carbon fiber/glass fiber reinforcement is of great interest. Glass fiber (GF)/carbon fiber (CF)/PET hybrid composites were fabricated by direct fiber feeding injection molding (DFFIM) process. The aim of DFFIM is to obtain longer fibers in composites in order to improve their mechanical properties. In this study, the mechanical properties of GF/PET composites fabricated by conventional injection molding and hybrid GF/CF/PET composites fabricated by DFFIM process were investigated. The influence of GF and CF volume fractions on fiber distribution, fiber orientation, and fiber length is discussed. Fiber distribution status was quantitatively measured by the fiber distribution index. Fiber agglomeration problem was observed by scanning electron microscopy. The results indicate that incorporating CF in GF/CF/PET hybrid composites by the DFFIM process greatly enhances mechanical performance even when only a small amount of CF is added. Too high GF content leads to less effective CF hybridization because it causes poor fiber distribution and poor fiber orientation and intensifies fiber attrition. The ideal volume fractions of GF and CF for fabricating GF/CF/PET hybrid composites by using DFFIM are provided.

Ammonium polyphosphate (APP) and inorganic fillers were applied for improving flame retardancy and mechanical performance of recycled poly(ethylene terephthalate) (RPET). RPET was compounded with 5-10 wt% of talc and glass bead using twin screw extruder then were injection molded with 2 wt% of APP. The effects of fillers contents and APP on properties and flame retardancy of RPET composites were investigated. The incorporation of talc and glass bead as well as the adding of APP significantly improved tensile and flexural modulus of RPET composites. Scanning electron microscope micrographs indicated good distribution of talc, while glass bead was agglomerated on the RPET matrix. Flame-retardant property of neat RPET and the RPET composites revealed V-2 of UL-94 flammability rating. It can be noted that the composites were less dripping because of the synergistic effect of adding talc and glass bead with APP. From thermogravimetric analysis results, larger of residual char contents and lower values of the activation energy were considered for enhancing flame retardancy in the RPET composites.

Abstract Blending of recycled poly(ethylene terephthalate) (RPET) and polycarbonate (PC) was performed by melt compounding. The blends were subsequently fabricated to dumbbell specimens by vented injection molding. The mechanical properties, thermal characteristic and morphology of RPET/PC blends were investigated as a function of PC contents. Vented injection molding presented an advantage for superior mechanical properties of RPET/PC blends. The addition of PC enhanced impact strength and fracture toughness with remaining tensile properties. The glass transition temperatures of PET and PC shifted toward each other, which indicated their partial miscibility of RPET and PC in the blends. The toughness mechanism of RPET and PC was related to core-shell structure and good interfacial adhesion at higher contents of PC.