Influence of Processing Parameters and Composition on the Effective Compatibilization of Polypropylene–Poly(ethylene terephthalate) Blends

Abstract

The effects of the addition of different functionalized compatibilizers on toughness, morphology and rheological properties of a polypropylene (PP) -poly(ethylene terephthalate) (PET) (85-15 wt%) blend were studied. The three compatibilizers compared were: (Styrene Ethylene Butylene Styrene)-grafted-(glycidyl methacrylate); (Styrene Ethylene Butylene Styrene) -grafted -(maleic anhydryde); (polyolefin) -grafted -(glycidyl methacrylate), abbreviated to: SEBS-g-GMA, SEBS-g-MA and POE-g-GMA respectively. The effective grafting content was the same for all three compatibilizers. Before the comparison of the different compatibilizers was done, first the effects of three different processing temperatures and three different compatibilizer contents were investigated, based on the addition of SEBS-g-GMA. The compatibilization effect was significantly improved with an increase in processing temperature from 250 to 300 8C. The toughness was increased with almost a factor two and a decrease in the average domain size of the dispersed phase was observed. An increase in compatibilizer content from 0.25 to 2.5 wt% resulted in a finer dispersity as well as in a steep increase in toughness, which was noted to approach the brittle-to-ductile transition. The comparison of the three compatibilizers was subsequently done at the most promising processing temperature and content: 300 8C and 2.5 wt%. The results showed that the addition of SEBS-g-MA and POE-g-GMA had a less significant positive effect on the compatibilization compared to SEBS-g-GMA. The difference is attributed to a higher reactivity for GMA compared to MA and a higher possibility for migration towards the PP-PET interface for the SEBS chain compared to the POE chain.

Upcycling of contaminated post‐industrial polypropylene waste: A design from recycling case study

“…The effect of the CA, however, is also obvious from the much better dispersion of the PET phase. All observed PET particles are now under 1 μm in size, mitigating also the embrittling effect of the non‐compatible polar PET in the apolar PP matrix . Both of these morphological effects lead to the dramatically increased impact strength, which is nearly quadrupled.…”

“…Therefore, we opt to include in the 15 wt% SEBS a small amount of 2.5 wt% CA, being a SEBS‐g‐MA, which is expected to effectively compatibilize the PET. MA has been found to be a good CA for PET in a PP matrix . Additionally, a CA will increase the interfacial adhesion between the PP matrix and dispersed PET phase, thus improving impact properties as energies can now be transferred more effectively between the two domains .…”

“…The EPDM rubbers were selected because they are generally cheaper and the compatibility with the PP matrix might be higher, based on the PP content in the backbone (additionally to the ethylene content, which is present in both types of impact modifier) [18]. The SEBS rubbers were selected because the styrene groups introduce a certain polarity, which has the potential to interact better with the PET contamination [5]. One impact modifier, which provided the best combination of flexural and impact properties, was selected as the additive for a large-scale industrial trial.…”

“…This is particularly the case for our material combination of polar polyethylene terephthalate (PET) in apolar polypropylene (PP). The polar PET will form large spheres within the PP matrix, thus reducing mechanical properties, impact strength foremost amongst them . Common methods to mitigate these effects include the addition of impact modifiers , which have a toughening effect when added in sufficient amount, or the more expensive compatibilizers .…”

Effect of copolymers synthesized by nitroxide‐mediated polymerization as chain extenders of postconsumer poly(ethylene terephthalate) waste

“…Consequently, there is a need to develop an appropriate technology for improvement of r-PET properties, to make it suitable for new applications. Several methods, such as the addition of virgin polymers [8], fillers [9], compatibilizers [10][11][12][13], and chain extenders [14][15][16][17][18][19][20][21][22][23][24] have been described in the literature to compensate for PET degradation by mechanical reprocessing.…”