OLD TO BECOME AS GOOD AS NEW : Pretreatment for gentle shredding

Abstract: In today’s World, sustainability is not just a buzz word but should be the new quality. In order to live in a pollution free environment, there is an urgent need to move towards a circular economy. The rapidly increasing demand of textiles results in high amount of textile waste leading to pollution. Textile to textile recycling is the most feasible solution to minimize textile waste while meeting the fashion demand. Mechanical recycling by shredding is one way of recycling textiles where, fabrics are broken down into their constituent fibres. The problem with this method is that, after shredding, there is huge reduction in fibre length due to the harsh process. This makes it difficult to use a high percentage of these reclaimed fibres in formation of new textile garments. The main focus of this thesis was to reduce the fibre length drop that occurs during shredding through lubricant pretreatment. It was anticipated that, inter-fibre friction would be the reason for the huge fibre length drop during shredding. Therefore, a method was developed to measure the inter-fibre friction of cotton and polyester staple fibres using a tensile tester. The effect of blending on inter-fibre friction was investigated. Different types of lubricants were used to alter the inter fibre friction. The lubricants were sprayed on the fibres and dried prior to carding. Two lubricants were chosen for pretreatment of fibres for yarn formation. The effect of the lubricant on the inter-fibre friction of carded fibre webs as well as yarn strength and spinnability were investigated. The results showed that, the method developed can be used to measure inter-fibre friction of staple fibres. It was also found that, inter-fibre friction in carded webs depends on the crimp and mechanical interlocking in the web. Inter-fibre friction in blended fibres depends on the percentage amount of each fibre in the blend. Addition of a small amount of lubricant significantly lowers the inter-fibre friction. The effect depends on the type of lubricant and type of fibre. Lubricant amount above 1.43% on weight of fibre lead to poor carding of fibres. Lubricant amounts between 0.29 % and 1% on weight of fibre lead to good carding of cotton and polyester fibres but the cotton fibre webs may not be spun. PEG4000 lubricant was found to significantly lower the inter-fibre friction compared to other lubricants. It was also found that, lubricants significantly affect the tensile strength of the yarn as well as their spinnability. Basing on the results, it was concluded that, lubricant pretreatment of fabrics prior to shredding will most likely provide a more gentle process. This was based on the fact that, the lubricants reduce the inter-fibre friction. This enables easier slippage of fibres within the yarns which facilitates easier deformation of the yarns during the shredding process. Thus reduce the fibre length drop. PEG 4000 is more likely to provide better results when used in amounts ranging from 0.1 to 0.71% on weight of fabric. Besides that, PEG is safe for the environment.