A journey into recycling of waste elastomers via a novel type of compatibilizing additives

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

Ester derivatives of experimental olefin-maleic anhydride copolymers synthesized at the University of Pannonia have been investigated by both classical and instrumental analytical methods that contribute to a deeper understanding of how that type of additives functions as compatibilizers for plastics and rubbers. Titration-based acid and saponification numbers have provided limited information about the chemical structure of the experimental copolymer compounds. A prompt, precise and low-cost method or combination of methods has been required to access to the ratio of the various derivatives not only straight after esterification but also for quality control during long-term storage considering the even stricter sustainability aspects either. Reproduction and scaling-up synthesises can be also followed by the combined measuring techniques of Fourier-transform infrared spectroscopy (FT-IR) and oscillatory rheometry. Structural changes occurred in the additives could be followed through monitoring their Ester Indices (EI) during the measurement, which can be connected also to the long-term properties. Experimental additives (AD) like AD-1 and AD-2 types with lower EI values of 21.5 % and 32.1 %, respectively, resulted in higher upper limits of the linear viscoelastic (LVE) range (15 % and 10 %). Conversely, the higher EI values of AD-3 and AD-4 led to significantly lower or even immeasurable upper limits of the LVE range. Additives with solid behaviour showed slight dependence on frequency above the crossover point that indicated strong connections disappearing.

A practical manner to GTR recycling in waste-HDPE/ABS

Waste high-density polyethylene (w-HDPE)/ acrylonitrile–butadiene–styrene (ABS)/ground tire rubber (GTR) have been melt blended by two-roll milling. Ternary blends of w-HDPE/ABS/GTR have been observed to be incompatible in the composition range studied which revealed in the deteriorated mechanical properties. Two main types of compatibilizers such as an experimental olefin-maleic anhydride copolymer based one synthesized by the authors and a commercial maleic anhydride grafted polypropylene (MA-g-PP) have been chosen for enhancing compatibility between the components ergo the mechanical properties. For characterizing tensile and impact properties of the blends mechanical tests have been carried out besides the scanning electron microscopy (SEM), X-ray diffraction and Fourier transform infrared spectroscopy. The most advantageous result in industrial practice can be that the experimental additive allows to apply higher GTR concentration ergo gives the opportunity to recycle higher level of GTR.

PE-contaminated industrial waste ground tire rubber: How to transform a handicapped resource to a valuable one

Sustainability and enhancement of recycling differing polymer waste has become a leading driver for industries associated with this type of waste. However, polymer waste streams that have not seen as 'typical' have existed in smaller but not insignificant amounts. This study has focused on the recycling of such a waste resource that is not classified as a typical one in developed countries but appears in other locations globally where opportunities for careful waste pretreatment are hindered, therefore creating a challenge for waste handling and the application of modern techniques. Compatibilizing is a strategy employed to recycle ground tire rubber (GTR) by blending with waste high density polyethylene (w-HDPE). Such processing methods and measurement techniques have been chosen to allow easy access without extra costs. For enhanced incorporation of the filler into the matrix olefin-maleic-anhydride copolymer based additives have been synthesized and have succeeded in creating a more homogenous blend with samples having a good surface appearance and mechanical properties. Outstanding Charpy impact strength at room temperature (10.1 kJ/m²) has been achieved in compatibilized 70/30 w-HDPE/GTR (containing 20% PE-contaminant), while elongation at break and tensile strength have been 10.3% and 14.9 MPa. Morphological structure of rubber resources and blends have been assessed by SEM while analytical properties and other features of experimental compatibilizing additives have been studied by e.g. FT-IR.