Environmental Footprints of Recycled Polyester pdf by Subramanian Senthilkannan Muthu

Contents

LCA (Life Cycle Assessment) on Recycled Polyester
Aravin Prince Periyasamy and Jiri Militky

Abstract Polyester is a synthetic material which is produced from the petroleum products. The various environmental impacts are associated with polyester from manufacturing to end of life. Therefore, the manufacturing of recycled polyester (rPET) is an important to process as concerned with environmental impact and also inevitable. The rPET has a wide scope of their potential applications similar to virgin polyester. Generally, life cycle assessment (LCA) technique investigates the environmental impacts of the particular products from its cradle to grave. Therefore, it helps to identify the critical phase which creates the maximum impact on the entire product life cycle. So, it is significant to understand the environmental impact of rPET, nevertheless, LCA on rPET is foreseeable. The data from the LCA can initiate preliminary steps to reduce the environmental burdens from the products, also it provides the detailed information on how it affects the ecosystem. In this chapter we discussed about the LCA on rPET, initially, the brief introduction will be provided about the present manufacturing techniques of rPET. Various issues associated with sustainability of rPET manufacturing, importance and methodology of LCA on rPET were explained in detail. Based on the LCA results, the important parameters with respect to the sustainability of rPET would be present in this chapter.

Keywords Cradle to grave · Polyester · Recycling · LCA · GWP

1 Introduction
The several natural fiberswere chiefly used for the production of textiles and garments until the seventeenth century [1, 2]. Either way today’s situation differs, according to the development of synthetic fibers in the late 1930s, these fibers are nowlargely used for textiles [3]. Polyester fibers are the examples of synthetic fibers containing ester groups in their main polymeric chain [4]. Polyethylene terephthalate (PET) having the ester group and generally known as polyester. In 2018, 106 million tons of global production compared to 25% cotton fibers, however, polyethylene terephthalate produced and consumes higher than any other textile fibers [5]. Eco-friendly industries and eco-friendly industrial practice has been promoted by the awareness created on environmental concerns. In the case of environmental benefits, the classical 3R can be implemented in the rPET industry, also it must be promoted to make awareness to the consumers [6, 7]. As it is known recycling is not new with vast history [8]. Last two decades, the awareness of sustainability and waste management results protection towards to the environment by practicing the more and more recycling process. Humanity poses large problems mainly due to plastic and polymeric waste in which crude oil is the first non-renewable materials which is the raw materials to produce various thermoplastic materials including the textile fibers. Majority of the synthetic materials consists of larger molecular size and rigid structure resulting non-biodegradable and non-decomposable. Accounting into the problems above it is advisory to recycle plastics and polymers and recycling motivates to decrease or lower landfill expenses, compared to virgin plastics recycled polymers are cheaper and further energy can be recovered from the plastic through various process [9]. 60% of the global PET produced with high-molecular weight further utilized to produce the textile fibers and 30% of PET is utilized to produce the bottles and other articles [10]. According to the reference [11], 70–80% of crude oil is used to produce virgin polyester, among them only 30–40% were recycled. Therefore, it is necessary to take attention which increase the recycling percentage, resulting the reduction of the environmental burdens by landfilling as well as carbon emission. In order to reduce our carbon footprint, larger companies receive tons and tons of paper and plastic which is recyclable. However, some of the statistics says 91% of plastics are not recycled, apart from that people buy millions of plastic bottles (food, beverages, water etc.) per minute [12]. In 2015, approximately 20% of textiles were reused in Sweden [13], in 2018 it can be increased to 40% as per the Swedish Environmental Protection Agency (SEPA) [14] and is predicted to increase further 20% in 2020. Figure 1 shown the recycled PET bottles% in various forms in the USA. Public imagination has been gathered by the idea of using recycled PET materials including bottles, molded articles, textile fibers, buttons etc. The concept of recycling has become green option, since it reduces the energy requirement for the production of virgin PET also reduce the consumption of non-renewable resources.

Generally, the textile wastes can be classified into three types, which are [15]:

• Wastes from pre-consumer stage
• Wastes from post manufacturing
• Wastes from post-consumer stage

Pre-consumer stage waste is defined as waste generated during the production, for example in textile productions, short fibers in the spinning, yarns in both weaving and knitting and fabrics from garment cutting and many. Generally, these wastes can be reused and produce different products, for example the short fibers were used to produce the coarser (i.e. thicker) fabric. After manufacturing, products having the defects are classified into the wastes from post manufacturing stage, perhaps it can be sold to very less price to the consumers or it will be reused and produced as same or different products.

Tomake rPET it includes the recycling of the accessories and beverage bottles as an example. Figure 2 summarizes the various routes of recycling and reuse of textiles. In any process waste is inadvertent and it has to be reused for the improvement of the environment. Recycling is the best solution for the polyester textile which drastically reduced the carbon emission and saves the energy as compared to virgin PET manufacturing.

If the materials were recovered from the waste use it again is called as reuse, whereas, after recovering, modify into the product is called recycling, meanwhile the recycled product is higher values than the original product is called as upcycling and lower values is called downcycling. There are four approaches for the recycling which is well explained in Fig. 3. Primary recycling defines the recycle of waste into original products. Recycling the post-consumer plastic waste into new products with reduced properties may classified into secondary recycling. Production of fuel or monomer from the PET waste are classified into tertiary recycling approach [17].