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Plastic film recycling from waste sources

Marsh, Richard. 2005. Plastic film recycling from waste sources. PhD Thesis, Cardiff University.

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This thesis focuses on the thermal recycling of plastic film materials that have originated from waste sources. The problems with waste plastic film recycling are outlined. The key aspects of this work included waste management, economics, logistics, the recycling industry, aspects of polymer science and the effect of the consumer environment on material properties of polymers. The aim of the research was to determine how these problems can be best understood and solved in order to prove that plastic film recycling is a sound opportunity from a financial and engineering point of view. A series of novel experimental studies were designed and performed to evaluate the effect that a film's life-cycle has on the material properties of the product. These studies involved exposing a number of polyethylene samples to factors such as heat cycling and dust contamination whilst measuring the characteristics of the material before and after exposure. Material tests included evaluation of mechanical and rheological properties, crystallinity content and molecular weight. As a natural continuation of the behaviour and characteristic studies already highlighted, two novel products namely a geomembrane and aggregate drainage material were manufactured. Tests were undertaken to determine the suitability of these under harsh environmental conditions. It was found that both materials were capable of meeting specifications laid down for application as engineering barriers. With the effects of a products' life-cycle understood, the investigation then involved the development of a predictive model. This anticipated the effects of these life-cycle factors and calculated the resultant physical properties of a plastic film material once it had been thermally recycled. This model used correlations between the key factor and the crystallinity of the polymer in order to determine the degradative effects. Results showed that key material properties could be modelled to within 15% accuracy of those found by experimental verification. To assess the feasibility of recycling plastic film an economic model was produced to simulate the financial performance of a recycling plant. Model inputs were based on industrial experiences and were used in conjunction with a series of operating parameters to outline economic feasibility. The simulation showed that profitability was closely related to the quality of the input material, the cost of procuring waste feedstocks and the price paid for the final product. Overall the thesis showed that plastic film recycling is a viable concept, provided recyclers sufficiently improve the quality of feedstocks by separation and washing, procure a reliable source of feedstock and operate a facility that is adaptable to changes in material condition. These factors must be undertaken with sound financial management to ensure that a profitable product is produced. Although there is a small number of possible recycled products to be produced from plastic film, more development is needed to create a demand for waste feedstock materials. This will ensure that mandatory recycling targets are met for government and businesses that are required by European legislation. This investigation has outlined many of the key factors to allow film recycling businesses to expand into future markets and produce recycled products of equal quality to that of existing products made from virgin stocks.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
ISBN: 9781303203725
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 06:03

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