Remarkable Role of Experimental Olefin-Maleic-Anhydride Copolymer Based Compatibilizing Additives in Blends of Waste PET Bottles and Polyamide

Abstract

Over the past 50 years demand for plastics drastically increased worldwide resulting in plastic wastes causing serious environmental problems. The main market sector of European plastics industry is the packaging industry most of which are polyolefins and poly(ethylene-terephtalate). In the EU, 29.1 million tonnes of plastic waste were collected in 2018, of which 32.5% was recycled, 42.6% was recovered for energy, and 24.9% was landfilled (Plastics-the Facts, 2019). Although landfilling of collected waste in the EU is steadily declining, there is still too much unused waste. Polymer blends based on waste resources can solve the issues of recycling. The main purpose of the research was to produce polymer blends from waste based PET that have appropriate mechanical properties and rheological behaviour as well in order to find application areas where product requirements are not strict. Blends containing waste based PET were extrusion moulded and calenderd producing extrusion strings and films. Rheological and tensile properties of three types of PET/engineering thermoplastic blends (PET/PC, PET/PA and PET/ABS) were studied. Miscibility of components of the blends is limited leading to weak mechanical properties such as low tensile strength and/or elongation at break. Due to that phenomenon compatibilizing additives are also required. As compatibilizing additives olefin-maleic-anhydride copolymer based additives have been used in our experiments. Structure of additives differed from each other both in ratio and length of carbon chains of compounds linked to maleic-anhydride groups. Blends have been studied with PET content ranging from 10 to 90%. As an outstanding result improving of mechanical properties was achieved, for example almost 40% growth was observed in elongation at break of extruded 80/20 PET/PA blends in the presence of 0.2% compatibilizing additive compared to the sample without additive, meanwhile its strength has also improved. Graphic Abstract

Shear-Induced Structure Formation in MAH-g-PP Compatibilized Polypropylenes

“…Maleic-anhydride-grafted polypropylenes are widely used to compatibilize glass-fiber-reinforced polypropylene composites − as well as thermoplastic blends − and (partially) biobased composites. ,− With increasing demand for high-end applications and the global strive toward full recyclability of polyolefins, compatibilization of such materials has regained the interest of both academia , and industry . Although several synthetic functionalization pathways are well-studied, ,− the subsequent effect on the bulk crystallization of isotactic polypropylene (iPP) is still underexposed; under quiescent conditions, Cho et al observed a slight increase in the crystallization temperature and thus in the non-isothermal crystallization kinetics above a critical grafting content .…”

FT-IR combined with oscillatory rheology: How to evaluate chemical structure of ester derivatives of MA-containing compatibilizers

“…In the additives containing functionalized MA, the acid number and the MA content/ratio do not offer sufficient information to select the appropriate compatibilizing additive for a given composite material based on its chemical structure, which would be more advantageous in many cases. The experimental olefin-maleic anhydride copolymer based additive, synthesized at the University of Pannonia, in which the anhydride ring was functionalized with various compounds, proved to be more advantageous in numerous composite system compared to the commercial MA-grafted polymer types [ [35] , [36] , [37] , [38] , [39] , [40] ]. The synthesis of olefin-maleic anhydride copolymer-based additives allows to applying the additive with the proper chemical structure in the various composite systems, since the structure of the additive can be tailored to the structure and polarity of the polymer and/or rubber components.…”