Following a study of the mechanical properties of recycled W C recovered from post-consumer bottles, this study focuses on the effects of recycled material on processing. In particular, the effects of multiple recycling were studied to investigate any problems that may arise due to the repeated incorporation of recycled material into the processing stream. Batches of recycled flake and powder as well as pure but processed bottle flake material were subjected to simulated multiple recycling using a Torque Rheometer. Ten minutes at 170°C followed by granulation represented one recycle. Molecular weight and Infi-ared analyses were performed to assess the degree of degradation occurring during reprocessing. The results indicated a rapid degradation of the two recycled grades when compared with the purer bottle flake W C . Further multiple recycling was then performed on bottle flake mixed with 0.2Oh polyethylene, which showed that the PE impurities accelerate the degradation process. Finally, the effects of restabilizing by adding new bottle flake material at each step were investigated. It was shown that surprisingly small levels of new material (30?h) prevented degradation, even after 15 recycle steps. IlWTRODUCTION n a previous paper (11, the mechanical behavior of I recycled post-consumer W C material was studied.The recycled material was obtained from the Reprise bottle separating plant, operated by EVC compounds Ltd. Two forms of the recycled material were studied: granules and pulverized powder. In addition, the behavior of virgin WC and pure but reprocessed bottle flake were studied as a comparison. It was found that the strength, ductility, fatigue, and Esc resistance of the recycled flake were considerably reduced compared with the virgin W C . i-effect predominantly due to the presence of large mpurity particles. Pulverization of the material did improve the performance but not to the levels of the virgin material. GPC analysis showed that there were no significant Werences in the molecular weight distributions of the three materials, and an impurity analysis showed that the levels of impurity were 0.3% by weight, mainly of PET, PE, and paper.In this study, attention turns to the reprocessing behavior of these materials. If recycled PVC is to be incorporated into the raw material stream in greater quantities, it will be important to fully understand the effects it has on processing behavior. There are cer-tainly concerns about the possibility of accelerated degradation during processing caused by recycled material, and so this part of the study is aimed at addressing these concerns, determining the causes of any accelerated degradation, and assessing the degree of restabilization that may be needed.There has been a large amount of work performed on the thermal, oxidative, and thenno-mechanical degradation of W C . It has been found that with predominantly thermal degradation, where little oxygen is present, the degradation proceeds by a process of dehydrochlorhation, which leads to the formation of conjuga...

The properties of recycled W C bottle material separated from the post-consumer waste stream were investigated. In the first part of this study, attention was focused on the mechanical properties. In order to examine the effects of recycling, the properties of the recycled material were compared with those of virgin W C and pure material that had been processed into bottles and then granulated. The effects of pulverization of the recycled material were also studied. The mechanical properties investigated included tensile, fatigue, and environmental stress cracking tests, in conjunction with fracture surface examination. molecular weight determination, and i m p~~-Q analysis. It was found that the recycled material did show significant reduction in strength and ductility, though pulverization improved the situation considerably. The main reason for this was the presence of impurities. especially PET, which although present at levels below 0.5%. had a large effect on the properties. IlpTIlODUCTIONver the past ten years, there has been a growing 0 awareness that a more sustainable solution is required to deal with the large amount of plastic waste produced, especially from packaging applications. It is currently estimated that over ten million tonnes of plastic waste are generated in Western Europe each year (1). A breakdown of this into plastic type is shown in Fig. I, from which it is clear that the major contributors are the packaging materials of PE, W C . PP, and PS. As legislation and the cost of landfill drive the need to reduce the amount of plastic waste going to landfill sites, a greater emphasis will have to be placed on recycling as one of the options. Currently, less than 200h of plastics produced across Europe are recycled (2). with the purer in-house generated waste (such as off-cuts) accounting for a significant part of this. In order to increase the proportion of packaging materials that can be recycled, there are many economic and social issues to address, but also some important materials considerations, and it is these that form the basis of this study.As drink bottles provide one of the easiest routes to collection and separation, these have been targeted as a sensible area in which to concentrate recycling effort. The materials investigated in this study originated from the Reprise pilot-scale bottle separating plant operated by EVC Compounds Ltd. This study focuses on the WC collected from this plant, and attempts to deal with the issues that are important if such recycled material is to be treated with confidence as an alternative to virgin polymer. These issues in-iii) a better understanding of the properties of the recycled material, characterization of molecular weight changes, the levels of separation purity required in order to achieve acceptable properties, and the influence of the recycled material on subsequent reprocessing.Studies of the effects of recycling on the mechanical properties of polymers have generally concentxated on the short-term strength properties (3)(4)(5)(6)(7)(8). ...

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