Rayon has the distinction of being the first man-made fibre developed in the wake of industrialisation of textiles, says Dr Ashok Athalye.
Though rayon was conceptualised in 1855 before synthetic dyestuffs were discovered, considering the complexity of the manufacturing process, it took over 50 years for its commercial production.
Until about a hundred years ago, textiles consisted of only the fibres available in nature. Clothing was made up of fibres of plant origin like cotton, jute, linen or wool and silk derived from animals. However, with growing population and increasing per capita consumption, technical advancements and industrial revolution, the need for newer textile fibres was felt.
Count Chardonnet of France patented the first process of rayon manufacturing in 1884 and is known as the 'Father of Rayon'. In 1905, he started bulk scale fibre production in the United Kingdom. This new fibre soon became popular and owing to its characteristic lustre, texture and feel, initially it was called artificial or imitation silk. In 1925, the US Federal Trade Commission (FTC) officially recognized and confirmed the term rayon as the regenerated cellulosic fibre.
Cotton is the most widely used natural cellulosic fibre but its consumption has almost reached a level of saturation owing to the limited area of cultivation, varying yield per hectare and growing need for other agricultural food crops. The global cotton production in 2017-18 is about 2.6 million MT with an average yield of approximately 800 kg/hectare.
Like cotton, rayon is also made of cellulose but it is regenerated from wood pulp through a chemical manufacturing process. At present, the global production of rayon is estimated to be about 6 million MT and India is the leading supplier having close to 24 per cent market share.
The chemical characteristics of rayon are similar to cotton and it provides soft, smooth and comfortable handle, while its drape and fall simulate properties similar to nylon. Further, the higher moisture absorption and the non-body clinging nature make it ideal for use in hot and humid weather.
Types and generations
Rayon manufacturing has evolved noticeably during its journey over the past century. Based on various modifications and changes, starting from the source of the basic raw material and usage of chemicals solvents to the incorporation of advanced mechanical technologies, it has transformed considerably. However, rayon fibres from each of these generations have unique properties and specific end use applications and thus are still being produced universally.
Viscose rayon is the most widely produced and used regenerated manmade fibre. In 1894, English chemists Charles Frederick Cross, Edward John Bevan and Clayton Beadle patented a safe and practical process of rayon manufacturing and named it Viscose. It is termed as the first-generation rayon.
It is made from cotton linter or wood pulp generally obtained from pine and spruce trees and passes through various processing stages involving alkaline soaking, xanthation and ageing. Recently, bamboo-based viscose was developed and gained popularity.The resultant material is supplied in both the staple fibre and in continuous filament forms.
Fibres are spun using different methods, namely pot spinning, spool spinning and continuous spinning, which characterise yarn size, diameter and strength. Different varieties of yarns, such as mono-filament yarns, multi-filament yarns and spun yarns, permit the manufacturing of a wide variety of fabrics suitable for apparel and home furnishings.