Recycled yarns coming from textile industries as reinforcement for PP composites

LÓPEZ, JOAN P.; VALLEJOS, MARÍA E.; CAÑIGUERAL, NURIA; CORRALES, FARNES; VILASECA, FABIOLA; MUTJÉ, PERE

Viena, Austria

Otro; 5th European Meeting on Chemical Industry and Environmen (EMChIE); 2006

Institute of Chemical Engineering Mechanical Process Engineering and Air Pollution Control Techniques Vienna University of Technology - Austrian Chemical Society (GÖCH)

Since the textile industry is generating huge amounts of residues, the increasing environmental consciousness and demands of legislative authorities is driving this sector in the sense of finding solutions to deliver the remainders into recycling processes and convert these waste products into resources. Nonetheless, before any conclusions can be made as to the best options for improving environmental sustainability in the textile industry, trends in fibre usage and production need to be analysed. Textile represent between 3%-5% of household waste and estimates for arising of textile waste vary between 550,000 tonnes and 900,000 tonnes each year. Over one million tonnes of textiles are discarded annually, mostly from domestic sources, of which 25% are recycled second hand, waste bags, wiping clothes, filling materials and fiber reclamation (“Textile recycling association”). The global market share of the principal textile fibres between cotton, polypropylene, wool, silk, acrylic, hemp, ramie, rayon, jute, polyester and polyamides. The predominance of cotton for the natural fibres, and polyester for the man-made fibres clearly shows up, the two accounting for some 65% of the total textile market. Within the textile industry there exists only limited options for fibre substitution. This is particularly true of the synthetic fibres, which have been developed to satisfy a need. Hence, the apparel category is dominated by polyester and cotton, with a smaller but significant volume of viscose and wool. A similar pattern is true of the domestic category, although the requirement for wool here is only tiny. Carpets use mainly nylon and wool. Industrial fibre usage is dominated by synthetics, which are used across a wide range of applications, from conveyor belts and geotextiles through to medical uses. Tyre production, which is also an industrial usage, but such an important one requires both synthetics and cellulosics for tyre backing materials. It is important to note that the car industry accounts for about 35 to 40% of the total fibre consumed by these last two categories. The consumption of fibres by end use gives a further indicator of trends in usage and subsequent wastage. The great quantity of textile remnant pieces is generally coming from the clothing industries, which are generally located in the third world countries [1]. This kind of textile residue is composed of different natural and synthetic fibres, such as cotton, acrylics, polyester [2]. Textile residues use to come from the process itself, but when these textile remainders are unravelled and further jointed, many textile residues are also generated, about 10% of the initial weight. It is worth noting that even in these days of increased environmental awareness, about a million tonnes of textiles are landfilled each year in the UK. To eliminate these textile residues, in Spain there are only two potential ways, the controlled rubbish dumps and the incineration process. Both possibilities are involved in the well-known environmental contamination and degradation troubles. The organised recovery of waste textiles can be traced back as far as the old clothiers, many of whom were farmers involved in all stages of textile production. However, the practice of recovering waste is probably as old as the art of spinning and weaving. Thus, waste cotton garments could not be pulled apart without creating too short a fibre and so waste cotton was generally used as a filling material and for cleaning cloths. To avoid these problems, a recycling alternative was proposed to convert waste into resources and textile residues were used as reinforcement for reinforced matrices. In this work, polyester, acrylic and cotton residues supplied by Fontfibra S.A. (Olot, Spain), were used to reinforce polypropylene from beer-recycled boxes. In a first step, the fiber length was reduced to a nominal length of 10 mm using a blade mill. Then, composite pellets at 40% wt were obtained using a Bravender mixer. Due to the high hydrophilic behaviour of some textile residues, such as cotton and acrylic, 6% wt of maleate polypropylene (MAPP) with respect to the reinforcement was incorporate during the mixing process to improve fibre-matrix adhesion. Specimens for mechanical testing were obtained by injection moulding using a 35Tn Mateu&Sole Injection Machine. The composite specimens were produced from standard mould according to ASTM D3641. Test specimens were conditioned according to ASTM D618 standard and then submitted to tensile and flexural tests using an Instron 1122 testing machine. Impact tests were obtained using a Charpy apparatus. The results were compared with samples of non-reinforced PP. Fiber distribution was observed from fracture surfaces using a scanning electron microscope (SEM) mark Zeiss DMS 960. The results shown that PP composites reinforced with cotton or acrylic fibres gave better mechanical properties than PP composites reinforced with polyester fibres. Thus, polyester/PP composites showed lower tensile strength although a stiffening 40% higher than that of non-reinforced PP. Besides this, acrylic/PP composites showed better tensile and flexural strength and an improvement in stiffening of 75%. Finally, cotton/PP composite provide a significant strengthening at both tensile and flexural assays and a stiffening of 150% and 175% at tensile and flexural assay, respectively. Additionally, scanning electron microscopy showed a good dispersion of the reinforcement within the matrix, which agrees with the mechanical results obtained. It could be concluded that this procedure is a good alternative for the recycling of textile residues to new composite materials that can be suitable for some marked application.