The automotive industry needs to produce plastic products with high dimensional accuracy and reduced weight, and this need drives the research toward less conventional industrial processes. The material that was adopted in this work is a glass-fiber-reinforced polyamide 66 (PA66), a material of great interest for the automotive industry because of its excellent properties, although being limited in application because of its relatively high cost. In order to reduce the cost of the produced parts, still preserving the main properties of the material, the possibility of applying microcellular injection molding process was explored in this work. In particular, the influence of the main processing parameters on morphology and performance of PA66 + 30% glass-fiber foamed parts was investigated. An analysis of variance (ANOVA) was employed to identify the significant factors that influence the morphology of the molded parts. According to ANOVA results, in order to obtain homogeneous foamed parts with good mechanical properties, an injection temperature of 300 °C, a high gas injection pressure, and a large thickness of the parts should be adopted.

The use of recycled polyethylene terephthalate (PET) as a matrix for composite materials based on glass fiber reinforced virgin PET could be a cost-effective and environmentally friendly way to upgrade the bottle-grade recycled PET into engineering-grade PET for injection molding. In this work, a commercial virgin PET reinforced with 50%wt of glass fibers was compounded by mechanical mixing with a recycled PET, in order to minimize breakage of the glass fibers. The obtained compound, composed by 60%wt of recycled pet and 40%wt glass fiber reinforced virgin PET, was injection molded at three different mold temperatures (4, 40 and 80 °C) to analyze the effect of crystallization of the material during the production process. The results in terms of thermal and mechanical properties were compared with those obtained from recycled PET molded in the same conditions. The flexural tests and the analysis of thermal resistance showed that by adding 40%wt of glass fiber reinforced virgin PET to the recycled PET causes a noticeable improvement of crystallization kinetics and of mechanical properties with respect to that of the pure recycled PET, making it suitable for technical applications.