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Summary The usage of plastic materials in daily life has continuously increased over the last 30 years. The amount of plastic consumed per inhabitant in the industrialized countries has increased by a factor of 60 over this period, while the generation of plastic wastes has grown at a similar rate. Recycling of plastic materials is now an important field in the plastics industry, not just an activity born under environmental pressure. The recycling processes include industrial operations in which secondary materials are reprocessed and/or monomers recovered for further polymerization; such processes are termed secondary and tertiary recycling. At present, there are three main alternatives for the management of plastic wastes in addition to land filling: (i) mechanical recycling by melting and regranulation of the used plastics, (ii) feedstock recycling and (iii) energy recovery. Consequently, feedstock recycling appears as a potentially interesting approach, based on the conversion of plastic wastes into valuable chemicals useful as fuels or as raw materials for the chemical industry. The cleavage and degradation of the polymer chains may be promoted by temperature, chemical agents, catalysts, etc. The purpose of this work is to describe and review the different alternatives developed for the feedstock recycling of plastic wastes, with emphasis on both the scientific and technical aspects.

The study of molecular level interactions in elastomer composites has got very scant attention even though a large number of studies are going on in this topic. This work embodies the understanding of confinement effects in natural rubber (NR)/ ZnO composites from micro to nano length scales, and their influence on macroscopic properties of the composites. The interactions between fillers and matrix are characterized from the Donth's approach, which allows estimating the cooperativity size Nα at the glass transition, Nα being directly related to the filler‐matrix interactions. The improved properties of NR‐nano ZnO composites can be attributed to microstructural and morphological changes due to nano ZnO in the NR matrix. A correlation between Nα, the constrained volume Cv and the thickness of immobilized polymer chains χm at the glass transition has also been established. Thus, this work proves that the Donth's approach is a powerful probe to estimate the enhance of mechanical properties in nanocomposites from calorimetric investigations.

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