Compatibilization of recycled poly(ethylene terephthalate) and polypropylene blends: Effect of polypropylene molecular weight on homogeneity and compatibility

Abstract

ABSTRACT:The effectiveness of compatibilizers in enhancing the dispersion of polypropylene (PP) at various molecular weights in recycled polyethylene terephthalate (RPET) was elucidated. The idea of incorporating PP of different molecular weights evolved from the intention of simultaneously recycling the PET bottles together with the PP-based bottle caps, which are often of low molecular weight (M w ). Three grades of PP with known molecular weights were blended with RPET at various loadings of compatibilizers. Morphological analyses suggest that the dispersion of the PP particles was more homogeneous, and the average particle size was smaller when low M w PP was incorporated. This indicates that the interaction between the compatibilizer and PP particles was more intense with the presence of a large number but shorter PP molecular chains. Moreover, specimens containing low M w PP were found to remain homogeneous regardless of compatibilizer and PP content in the RPET/PP blends. The homogeneity of the blends significantly affected their mechanical performance as well. Higher stiffness, yield strength, deformability, and toughness were observed when low M w PP was incorporated, regardless of PP and compatibilizer loadings.

Optimization of mechanical performance of compatibilized polypropylene/poly(ethylene terephthalate) blends via selective dispersion of halloysite nanotubes in the blend

“…Polypropylene (PP)/poly(ethylene terephthalate) (PET) blends with PP as the major phase are widely studied and used in many application areas, especially in packaging materials 1–6. For example, flexible intermediate bulk containers (FIBCs), a typical PP/PET blend in which the PET content is about 10 wt %, are widely used in the industry for the transport and storage of powders, granules, or pellets 7–9.…”

Effectiveness of Compatibilizer on Mechanical Properties of Recycled PET Blends with PE, PP, and PS

“…On the other hand, the fillers such as talc or CaCO 3 were used in order to improve the thermal resistance and flame retardancy of RPET/RPP blends [5]- [9]. Inoya et al [10] [11] has reported on hydrogenated block-copolymer of SEBS for improving the compatibility of R-PET with PP blends. Many investigations had been performed on polymer blends involving RPET bottles from post-consumer waste PET bottles with discarding caps and labels.…”

Recycling Polymer Blends

“…As expectable, adding the SEBS rubbery compatibilizer caused an increase of ductility and impact resistance. Since 15 phr of compatibilizer is a too high amount in terms of costs, another way is to change the PP molecular weight (Inoya et al 2012). In this case, lower molecular weight PP helps with the diffusion of the compatibilizer inside the melt and the maximization of its concentration at the interface, allowing the reduction of the compatibilizer amount.…”

“…Some authors (Inoya et al 2008;Inoya et al 2012) studied the effect of the compatibilizer level (SEBS) on the mechanical properties of r-PET/PP blends. The addition of up to 15 phr of compatibilizer resulted in a size reduction of the dispersed phase, while a slight increase in density suggested an improvement on interfacial interactions.…”