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| SCIENCE TRIBUNE | Thursday, February 17, 2000, Chandigarh, India |
Evolution of textile fibre by J.N. Vohra SCIENCE made substantial and significant inroads in the field of textiles with the discovery of man-made fibres, at the fag end of the last millennium. For thousands of years, humans have been using natural fibres such as cotton, linen, wool and silk for the manufacturing of textiles. But these fibres had some inherent shortcomings. Cotton and linen wrinkle from wear and washings. Wool shrink and matt on washings. Silk requires delicate handling. The human quest for newer fibres, which are without these deficiencies, led to the discovery of manufactured fibres. Flyash use gaining
acceptance Fighting
ovarian cancer Science
Quiz |
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Evolution of textile fibre SCIENCE made substantial and significant inroads in the field of textiles with the discovery of man-made fibres, at the fag end of the last millennium. For thousands of years, humans have been using natural fibres such as cotton, linen, wool and silk for the manufacturing of textiles. But these fibres had some inherent shortcomings. Cotton and linen wrinkle from wear and washings. Wool shrink and matt on washings. Silk requires delicate handling. The human quest for newer fibres, which are without these deficiencies, led to the discovery of manufactured fibres. It is only in the 19th century that a Swiss chemist saw the possibility of manufacturing textile fibres in the laboratories. He dissolved the inner bark of a mulberry tree and chemically modified it to produce cellulose. He dipped needles into this solution and by drawing them out he saw formation of filaments. On solidification these filaments formed threads flexible enough to be used for the manufacturing of textiles. That was the beginning of using the secrets of chemistry for countless applications to textiles. Using the principles of polymer chemistry later, nylon, polyester, acrylic and scores of other fibres were manufactured, which now find innumerable applications in the field of textiles. These fibres overcame most of the deficiencies of natural fibres, but uncovered their own like skin allergy, inflammability, difficulties in colouring and disposal. Moreover, factories producing man-made fibres became source of atmospheric pollution. Gradually problems of manufactured fibres are being solved. In 1889, a French chemist transformed the success of laboratory scale experiment to first commercial scale production of a manufactured fibre, viscose. The lustre of viscose resembled silk so initially they called it “artificial silk”. Viscose also has similarities with cotton in brightness and structure, since chemical composition of cotton is also cellulose. So later they named it as “rayon”, a short of “Sunray & Cotton”. The commercial production sequence of viscose is shown in the figure. The process in short constitutes rebirth of cellulose extracted from wood pulp of trees in the form of filaments. Cellulose is the natural polymer that makes up the living cells of all vegetation. It is the most abundant and replenishing biopolymer on earth. In the course of its regeneration into filaments, wood pulp is given various chemical treatments. The pulp is first purified, bleached with sodium hypochloride to remove natural colour of the wood, and soaked in caustic soda for producing alkali cellulose. Then the substance is broken up into crumbs. These pieces of alkali cellulose are turned into cellulose-xanthate by adding liquid carbon disulphide. The cellulose-xanthate crumbs are then dissolved in a weak solution of caustic soda, which transforms the crumbs into a thick solution called viscose. This solution resembles honey in colour and consistency. The viscose liquid is then forced through the holes of a spinneret, which resembles a bath shower, into a sulphuric acid immersion. When the extruded streams of cellulose xanthate come in contact with sulphuric acid, these coagulate to form pure regenerated cellulose filaments. These filaments may be further cut into smaller lengths to produce staple fibre. The variation in production techniques and adding some external chemicals in the solution or bath influence many properties of viscose such as lustre, strength, softness, and affinity for dyes. The other regenerated cellulose fibres are acetate rayon, cuprammonium rayon, polynosic and recently developed lyocell fibre. Developments in the manufacturing process of regenerated cellulosic fibres evolved “Lyocell”. The manufacturing of lyocell is a safety-tested process, since it uses a non-toxic dissolving agent, which is recovered, purified and recycled as an integral part of the manufacturing process. Waste products are thus minimal and harmless. Lyocell fibre is eco-friendly since products made from it can be recycled or destroyed by fire and is also biodegradable. the credit for the discovery of lyocell fibre goes to Courtaulds, USA who pioneered the manufactured fibre industry by commercialising the viscose process. Lyocell fibre is marketed by Courtaulds under the trade name ‘Tencel’. The writer is a
textile consultant |
Flyash use gaining acceptance THE Fly Ash Mission (FAM) is claimed to have made a considerable impact on improvement of the flyash utilisation/safe disposal scenario in the country. The Fly Ash Mission, a technology project in Mission Mode of Government of India commissioned in 1994, is a joint activity of the Department of Science and Technology (DST), Ministry of Power (MOP) and Ministry of Environment and Forests (MOEF), wherein Department of Science and Technology is the nodal agency and technology information, forecasting and assessment council (TIFAC) is the implementing agency. The prime objective of the Mission is to undertake technology demonstration projects towards developing confidence in flyash utilisation and disposal. As on March 31, 1998, 40 technology demonstration projects had been approved/commissioned on (i) characterisation of flyash (ii) hydraulic structures (iii) handling and transportation of flyash (iv) agriculture related studies and applications (v) ash ponds and dams (vi) reclamation of ash ponds for human settlement (vii) roads and embankments (viii) underground mine fills (ix) research projects and (x) building components. Eight projects, according to the annual report of the Department of Science and Technology, Government of India, were completed and most of the projects are at advanced stages of progress. Good results are claimed to have been obtained and multiplier effects have also started in a good number of cases. Before the initiation of the Fly Ash Mission, the scenario of flyash utilisation/disposal was alarming. Of the 50 million tons of flyash being produced annually only about 3-5 per cent was being utilised and in limited areas. However, now the situation has improved. Now the annual utilisation has crossed 7.5 million tons (9 per cent of the increased production. During 1993 it was 1.2-2 million ton equivalent to 4.5 per cent of 50 million ton production). Confidence building activities of Fly Ash Mission have triggered the acceptance of flyash bricks by more and more agencies. The Indian Institute of Technology, Delhi and the American Embassy have accepted and used flyash bricks. Private agencies are getting encouraged and many individuals are coming forward to set up flyash brick manufacturing units. The CPWD has agreed to reconsider permitting the use of flyash cement in its construction. Use of flyash in the construction of roads and embankments, according to the report, has been successfully demonstrated in the country. It is gaining acceptance. The Ministry of Surface Transport and the Central Public Works Department (CPWD) have in principle accepted this use of flyash and have cleared/executed a few projects. Flyash specifications are being incorporated in forthcoming projects also. In addition, there are 8-10 road/embankment projects, wherein flyash has been used. Its use in Nizamuddin bridge road embankment of about 2-km length and 8-m height in a flood zone have demonstrated the flyash use even in adverse conditions. This has not only saved the topsoil and used flyash, otherwise a waste, but has also saved Rs 1.4 crore in a total project cost of about Rs 10 crore. Use of flyash for construction of ash pond dykes has started getting wider acceptance. More dykes are being constructed with flyash resulting in reduced demand of land for flyash disposal. Use of flyash as a structural fill material for reclaiming low lying areas has also started getting acceptance by the users. Use of flyash in agricultural applications has been well demonstrated and has been accepted by a large number of farmers. This use is claimed to have been picking up with the farmers. Analysis of heavy/toxic elements and nutritional aspect of agro-produce on flyash treated soil has also been initiated. Network has been developed among research and development (R&D), academia and other agencies for exchange and sharing of information/expertise. To summarise, the
intrinsic worth of flyash, according to the report, for
various gainful applications has started getting
recognition. It is now being taken as a friendly and
useful resource. |
Fighting ovarian cancer Scientists attached to a hospital in London have discovered that an antibody which alerts the body’s defences to the presence of pollen and other allergens can also be used to fight ovarian cancer. In a report in the European Journal of Immunology, the researchers said when they injected the IgE antibody common in many allergies into mice with ovarian cancer, they inhibited the growth of the tumour. “Early indications show that by harnessing the body’s natural defences, this antibody has the potential to stimulate the immune system into producing cells that are able to attack this cancer,” Prof Hannah Gould, a molecular biologist said. Ovarian cancer kills 15,000 women in the United States alone each year. It is dubbed the “silent killer” because there are no symptoms in its earliest stages. Three-quarters of women
with the disease do not realise they have it until it is
advanced. The five-year survival rate from the initial
diagnosis is 46 per cent. Surgery to remove the tumour
and chemotherapy are the standard treatment. — ANI
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Science Quiz 1. “Science is not a matter of merely looking at the test tubes and mixing this or that and producing things big and small.Science is ultimately a way of training the mind and the whole life’s functioning according to ways and methods of science....” who said this?2. There has been a phenomenal advancement in the fields of electronics and telecommunication technology in the recent years. What type of revolution is it called? 3. The genuinity of currency notes can be assertained by illuminating a note by a special type of light. This light provides a “fingerprint” (dimensions, composition etc.) of the note under investigation which helps distinguish between a real and a fake note. Which light are we talking about? 4. Name the instrument used by the doctors to examine the interior of the eye. Which type of a simple optical device is used in it? 5. A hygroscopic solid may absorb water from the atmosphere to such an extent that a concentrated solution of the solid is ultimately formed. What is this process called? 6. Formalin is used as a preservative for biological specimens. What is it chemically? 7. This lake in Punjab is considered as one of the six wetlands of India of international importance but it has become a soft ground for poachers who kill thousands of birds, fishes and animals for their meat every winter. Which sanctuary are we talking about? 8. Maxillofacial and cosmetic surgery is used for changing the facial appearance of a person according to his/her liking. What is the special form of this surgery called which involves changing the shape of one’s nose? 9. In mineralogy and chemistry, this term implies the existence of a substance in two or more crystal forms. In Biology and Botany, it means the existence of two or more types of individuals within a single species. Which is this term? 10. What did the US physicists Martin Fleischmann and Stanley Pons announce in 1989 the results of which could not be confirmed and were even refuted by some other scientists? Answers: |
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Electronic purse Suppose a person wants to pay Rs 500 to a shopkeeper. He will take out his electronic purse and punch in his personal identification number. Necessary instructions for payment will be issued by means of a software command. The purses of the person and the shopkeeper will be placed side by side. They will communicate directly through light-emitting diodes and lightsensitive transistors. The transaction shall be over within seconds. The balance in one purse will decrease by Rs 500 and it will increase by a similar amount in the other purse. To renew the contents of the purse the person can go to the bank and plug his purse into a terminal. This terminal is similar to an ATM. Such a communication from home, by telephone, is also possible. The bank will extract from the purse, the information about every transaction since last updating. The recorded transactions from the electronic purse will be transferred to a clearinghouse. Here the transactions made against other purses are checked for consistency. The electronic purse of the new millennium is a blend of convenience and security. In case a purse is lost, the finder will be unable to use it since he is unaware of the personal identification number (PIN). The balance can be easily reconstructed at the electronic clearinghouse. Electronic purse will ultimately pave the way for a cashless society. — Deepak
Bagai |
New products & discoveries — IT Digest Real estate
portal As per the agreement, visitors to the full service portal, mantraonline.com can instantly search for the properties listed in over 43 cities in India by clicking on the hyperlink of indiaproperties.com on the home page of mantraonline.com. This alliance is one of the first of its kind in the Indian Internet industry where a horizontal portal has tied-up with a vertical portal site. First Indian web
brand It facilitates the creation of instant fully multimedia enabled websites by adopting a mass customisation approach that shifts the focus from a do-it-yourself model to a do-it-for-me model. Vsplash.com guides customers through an incredibly easy 7-baby-steps to creating their websites besides offering additional benefits like an entire range of look and feel options and other value added accessories. Logix ties up
with Centra Software Logix will provide a virtual training centre, which will be available to its customers round the clock. By using “Symposium” as an integral part of its implementation offering, Logix will offer its clients a seamless process to start using Internet as an online training programme. Sega tech for
Nortel Networks The huge number of interactive game players is being made possible through Nortel Networks’ high-performance Internet technology that is being provided to ISAO, the builder of one of the world’s largest and fastest game server network. Rediff.com in
Hindi — R.
Suryamurthy and Gaurav Choudhry |
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