Thermomechanical recycling of post-consumer poly(ethylene terephthalate) bottles and post-industrial polyamide 6 fishing nets reinforced with organo- modified montmorillonite

This study involved the recycling of post-consumer poly(ethylene terephthalate) (PET) and post-industrial polyamide 6 (PA6). Their blends and nanocomposites were melt fabricated using twin screw extruder and injection molding machine. Recycled PET (rPET)/recycled PA6 (rPA6) blends were first prepared at five weight ratios (90/10 to 50/50). Scanning electron microscopy (SEM) depicted a sea-island morphology on their fractured surfaces, where rPA6 formed dispersed droplets within the rPET matrix. Their melt flow index (MFI) decreased with increasing rPA6 content, suggesting an increased melt viscosity. Comparing with neat rPET, tensile strength, elongation at break, and impact strength of the blends were enhanced along with the expense of Young’s modulus. The blend with 30 wt% rPA6 was further mixed with a small loading of organo-modified montmorillonite (OMMT) (1, 3, and 5 phr) using the same processing conditions. X-ray diffraction and transmission electron microscopy confirmed the presence of an exfoliated structure in the nanocomposites. SEM images showed that the addition of OMMT caused rPA6 domains to increase in size because OMMT had a strong tendency to move towards the rPA6 phases and selectively localized within or at the interface of the rPA6 domains. The MFI of the nanocomposites decreased continuously with increasing OMMT contents compared to that of the neat blend, implying an increased melt viscosity. Finally, the results revealed that only the nanocomposite containing 1 phr OMMT exhibited an increase in all the evaluated mechanical properties over the neat blend, which can make the recycled materials more suitable for a wider range of applications.