Quality Assessment for the Improved Use of Recycled Styrenic Polymers: Application to packaging and electronic waste
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Polymeric waste materials should be considered resources for the manufacture of new products through recycling processes, with a similar status as virgin fossil-based plastics and biopolymers from renewable resources. Several efforts can be done to achieve this qualitative quantum leap and introduce recycled products in the market with competitive performance. Detailed scientific knowledge about the degradation processes to which polymeric materials are subjected under their life cycle is important when discussing their further waste recovery possibilities and the performance of recycled plastic. The development of fast and reliable analytical methods for the quality assessment of recycled plastics is fundamental to guarantee their performance in new applications. Three key quality properties have been previously defined for this quality analysis: degree of mixing (composition), degree of degradation, and presence of low molecular weight compounds (degradation products, contaminants, additives).A dual experimental approach employing multiple processing and thermooxidation is proposed to model the life cycle of recycled high-impact polystyrene (HIPS) used in packaging applications, and in electrical and electronic equipment (E&E). Both reprocessing and thermo-oxidative degradation are responsible for coexistent physical and chemical effects (chain scission, crosslinking, apparition of oxidative moieties, polymeric chain rearrangements, and probably physical ageing) on the microstructure and morphology of polybutadiene (PB) and polystyrene (PS) phases; these effects ultimately influence the long-term stability, and the rheological and mechanical behaviour of HIPS. The PB phase has proved to be the initiation point of HIPS degradation throughout the life cycle. Thermo-oxidation seems to have more severe effects on HIPS properties; therefore, it can be concluded that previous service life may be the part of the life cycle with the greatest influence on the recycling possibilities and performance of HIPS recyclates in second-market applications.Different strategies are presented for the quality analysis of recycled styrenic polymers from packaging waste and electrical and electronic equipment. The results from the life cycle degradation simulation were compared with those obtained from real samples from a large-scale mechanical recycling plant. The presence and emission of low molecular weight compounds from recycled HIPS from packaging waste has been critically discussed using solvent and headspace extraction procedures. Special attention has been devoted to the determination of brominated flame retardants in recycled HIPS from electrical and electronic equipment using advanced extraction and chromatographic techniques, due to the legislative and environmental implications of these additives.
Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 57 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2008:63
IdentifiersURN: urn:nbn:se:kth:diva-4895ISBN: 978-91-7415-112-1OAI: oai:DiVA.org:kth-4895DiVA: diva2:1802
2008-10-09, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Jimenez, Alfonso, Prof.
QC 201009202008-09-252008-09-172010-09-20Bibliographically approved
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