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塑料回收英文文献和中文翻译

时间:2019-03-30 21:00来源:毕业论文
Nextek Ltd, Level 3, 1 Quality Court, Chancery Lane, London WC2A 1HR, UKPlastics are inexpensive, lightweight and durable materials, which can readily be moulded into a var-iety of products that find use in a wide range of applications. As

Nextek Ltd, Level 3, 1 Quality Court, Chancery Lane, London WC2A 1HR, UKPlastics are inexpensive, lightweight and durable materials, which can readily be moulded into a var-iety of products that find use in a wide range of applications. As a consequence, the production ofplastics has increased markedly over the last 60 years. However, current levels of their usage anddisposal generate several environmental problems. Around 4 per cent of world oil and gas pro-duction, a non-renewable resource, is used as feedstock for plastics and a further 3–4% is expendedto provide energy for their manufacture. A major portion of plastic produced each year is used tomake disposable items of packaging or other short-lived products that are discarded within a yearof manufacture. These two observations alone indicate that our current use of plastics is not sustain-able. In addition, because of the durability of the polymers involved, substantial quantities of discardedend-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide.Recycling is one of the most important actions currently available to reduce these impacts andrepresents one of the most dynamic areas in the plastics industry today. Recycling provides oppor-tunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal.Here, we briefly set recycling into context against other waste-reduction strategies, namely reductionin material use through downgauging or product reuse, the use of alternative biodegradablematerials and energy recovery as fuel.While plastics have been recycled since the 1970s, the quantities that are recycled vary geographi-cally, according to plastic type and application. Recycling of packaging materials has seen rapidexpansion over the last decades in a number of countries. 34043
Advances in technologies and systemsfor the collection, sorting and reprocessing of recyclable plastics are creating new opportunitiesfor recycling, and with the combined actions of the public, industry and governments it may bepossible to pert the majority of plastic waste from landfills to recycling over the next decades.Keywords: plastics recycling; plastic packaging; environmental impacts; waste management;chemical recycling; energy recovery1. INTRODUCTIONThe plastics industry has developed considerably sincethe invention of various routes for the production ofpolymers from petrochemical sources. Plastics havesubstantial benefits in terms of their low weight,durability and lower cost relative to many othermaterial types (Andrady & Neal 2009; Thompson et al.2009a). Worldwide polymer production was estimatedto be 260 million metric tonnes per annum in the year2007 for all polymers including thermoplastics,thermoset plastics, adhesives and coatings, but notsynthetic fibres (PlasticsEurope 2008b). This indicatesa historical growth rate of about 9 per cent p.a.Thermoplastic resins constitute around two-thirds ofthis production and their usage is growing at about5 per cent p.a. globally (Andrady 2003).Today, plastics are almost completely derived frompetrochemicals produced from fossil oil and gas. Around 4 per cent of annual petroleum production isconverted directly into plastics from petrochemicalfeedstock (British Plastics Federation 2008). As the man-ufacture of plastics also requires energy, its production isresponsible for the consumption of a similar additionalquantity of fossil fuels. However, it can also be arguedthat use of lightweight plastics can reduce usage of fossilfuels, for example in transport applications when plasticsreplace heavier conventional materials such as steel(Andrady & Neal 2009; Thompson et al. 2009b).Approximately 50 per cent of plastics are used forsingle-use disposable applications, such as packaging,agricultural films and disposable consumer items,between 20 and 25% for long-term infrastructuresuch as pipes, cable coatings and structural materials,and the remainder for durable consumer applicationswith intermediate lifespan, such as in electronicgoods, furniture, vehicles, etc. Post-consumer plasticwaste generation across the European Union (EU)was 24.6 million tonnes in 2007 (PlasticsEurope2008b). Table 1 presents a breakdown of plasticsconsumption in the UK during the year 2000, and con-tributions to waste generation (Waste Watch 2003). This confirms that packaging is the main source ofwaste plastics, but it is clear that other sources suchas waste electronic and electrical equipment (WEEE)and end-of-life vehicles (ELV) are becomingsignificant sources of waste plastics.Because plastics have only been mass-produced foraround 60 years, their longevity in the environment isnot known with certainty. Most types of plastics are notbiodegradable (Andrady 1994), and are in fact extremelydurable, and therefore themajority of polymersmanufac-tured today will persist for at least decades, and probablyfor centuries if not millennia. Even degradable plasticsmay persist for a considerable time depending on localenvironmental factors, as rates of degradation depend onphysical factors, such as levels of ultraviolet light exposure,oxygen and temperature (Swift & Wiles 2004), whilebiodegradable plastics require the presence of suitablemicro-organisms. Therefore, degradation rates varyconsiderably between landfills, terrestrial and marineenvironments (Kyrikou & Briassoulis 2007). Even whena plastic itemdegrades under the influence of weathering,it first breaks down into smaller pieces of plastic debris, butthe polymer itself may not necessarily fully degrade in ameaningful timeframe. As a consequence, substantialquantities of end-of-life plastics are accumulating in land-fills and as debris in the natural environment, resultingin both waste-management issues and environmentaldamage (see Barnes et al. 2009; Gregory 2009;Oehlmann et al. 2009; 塑料回收英文文献和中文翻译:http://www.lwfree.cn/fanyi/20190330/31406.html
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