Technical textiles-Technological and market developments ...nopr.niscair.res.in/bitstream/123456789/19229/1/IJFTR 22(4) 213-221... · Indian Journal of Fibre & Textile Research Vol.

Indian Journal of Fibre & Textile Research Vol. 22, December 1997, pp. 213-221

Technical textiles-Technological and market developments and trends

Roshan L Shishoo

The Swedish Institute for Fibre and Polymer Research , Molndal , Sweden

Teclmical textiles are used in various forms of fibrous structures from simple filament to complex end products. This paper reviews, in brief, the various high performance and high functional textiles both from the market development and application points of view. The technology and material trends in the area of technical textiles have also been discussed.

Keywords: Air bags, Composites, Geotextiles, High functional textiles, High performance textiles, Industrial textiles, Technical textiles

1 Introduction At present, there is no standard definition of

technical textiles. One of the definitions proposed is: technical textiles are semi-finished or finished textiles and textile products manufactured for per­formance characteristics; they are used in indus­trial; institutional, civil eQgineering, medical, pro­tective and leisure applications. This definition clearly points out the diversity of materials, chemicals and processes used to produce technical textiles. Fig. 1 shows that a technical textile prod­uct can exist and be used in various forms of fi­brous structures from simple filament to a complex end product. The most common textile products in this category include high perforinance fibres, ropes, webbings, tapes, filter media, paper making felts and fabrics, heat and sound insulators, coated

Fig. 1~low chart showing various forms of fibrous structures of technical textiles

fabrics, protective clothing, composites, agrotex­tiles, geotextiles, and medical and hygiene prod­ucts.

Global market volume of technical textiles var­ies depending on the type of end-use applications. Higher value products exist at the upper end of price level at lower volumes and these are used in very specialised products where the performance, not the price, is the determining factor (Fig. 2) . The technical textile market occupies an important place in the total textile scene accounting for about 24% of all fibres consumed in Western Europe in 1994 (Table 1); this segment of the textile market is growing at a high rate. The producers of techni­cal textiles have been concentrating their efforts in improving their strategic position, productivity,

Carbon fibre

Tecbnical textiles

High performance and

. h functional

Bulk textiles

8 composites ·c fibre d textiles ~

Protective clothing

Woven fabrics

Knitte household apparel

Global market volume

Fig. 2-Global market volume vs price for textiie product,

214 INDIAN J. FIBRE TEXT. RES ., DECEMBER 1997

Table I-Per cent amount of fibres consumed for different applications in European Union and USA in 1989 and 1994

Application area

USA C lothing and household textiles Carpets Technical textiles including tyres

European Union Clothing and household textiles Carpets Technical textiles including lyres

Fibres consumed, % 1989 1994

39 33 28

60 18 22

35 34 31

54 22 24

value-added products, and niche positions in order to expand their markets.

China 11 %

Japan 8%

South Korea 8%

4%

J i:UWi::Ul

11%

Other Asia 9%

Western Europe

Eastern Europe 5% 6%

USA 19%

Fig. 3~eographical breakdown of world man-made fibre production in 1995 (source: Akzo Nobel)

David Rigby Associates ' provided a compre- a Polya..midr C Pclyacryllc.PoIYlPSlrraOthlPr synthlPtic

hensive overview of the international market for ~- 100

technical textiles . According to them, it is very .: 80

much likely that the actual consumption of fibres .; o

and yams for technical and industrial purposes is :;. higher 'than that assumed previously. An average ~ 2

growth rate of 4% per year caT! be expected during u: 1995-2005. The biggest market is Asia with sales

1975 1980 VlPar

1985 1990 1995

of $9.48 billion in 1995 ($ 14.18 billion in 2005), followed by North America with $ 8.37 billion ($ 10.57 billion in 2005). Hence, with an annual growth rate of over 5%, the Asian market will ex­pand twice as quickly as the North American mar­ket (2.5%) in the same period. Western Europe consumed fibres and yams worth $ 6.3 billion in 1995, a figure which is expected to rise to approx: $ 8.14 billion by 2005. World-wide, the average rate of growth in the consumption of techriical tex­tiles (woven fabrics, interlaid scrims, braiding, knitted fabrics, nonwovens, composites and mis­cellaneous fabrics) amounts to 4% per year during 1985-2005 . At present, the total sale is estimated at approx. US $ 42 billion. According to prognoses, this figure will have risen to almost US $ 61 billion by the year 2005 ~ In Western Europe alone, 2.3 million tons of technical textiles were produced in 1995. The resulting sale was worth approx. US $ 9.9 billion, which is expected to climb to US $ 12.9 billion by the year 2005 (ref. 1).

2 Market Developments The global growth of synthetic fibres continues

unbroken. Betw'een 1984 and 1994, the world synthetic fibre production increased over 7 million tons . A further increase of some 10 million tons is

Fig. 4--Shares by fibre type of world synthetic fibre produc­tion during 1970-1995 (source: Akzo Nobel)

expected by the year 2002. The regional distribu­tion of world fibre production will be shifting fur­ther to the dynamic Asian region. Rapidly growing market~ are India, China, Indonesia, Malaysia, South Korea, Taiwan, Thailand and in near future Vietnam (Fig. 3). Shares by fibre type of world synthetic fibre production during 1970-1995 are shown in Fig 4. There have been new develop­ments both in the fibre/filament and yam spinning technologies, resulting not only in higher speeds but also in better quality. Some leading manufac­turers today offer machines for take-up speeds of as high as 8000 mlmin and the development of machines for 10000 mlmin is already under way.

Requirements to be met by technical yams and fibres such as high tenacity, low elongation at break, high modulus, low thermal shrinkage, high thermal stability, high resistance to corrosive chemicals, etc. have placed great challenges to the R&D people at the major fibre producers. In many countries, the debate regarding environmental loading of oil-based polymers has also influenced the developm~nt of materials and products. In Europe, some important outlets for fibres, notably

SHISHOO: TECHNICAL TEXTILES 215

the traditional textile and apparel sectors, are in long-term declining while other markets like tech­nical textiles are continuing to expand. Mill con­sumption of man-made fibres in 1994 was nearly 3 million tons. The man-made fibre consumption in technical textiles in Western Europe in 1995 is shown in Table 2. Within the man-made fibre con­sumption of technical textiles, polyester fibres with a share of 34% are still in the lead, but during the past years polypropylene fibres have caught up considerably (80% increase within 5 years); so, by the year 2000 both the fibres are expected to reach equal quantities.

Table 2-Market trends of man-made fibres for technical textiles in Western Europe during 1995

Fibre Consumption in Tecbnical Textiles (Total 1.1 m tons)

Tons x 1000 % Share

Polyester 350 34 Polypropylene 330 31 Polyamide 130 II Acrylics 30 2 Cellulosics 230 22

Fibre Processed in Technical Textiles (Total 1.1 m tons)

TonsxlOOO % Share Nonwoven (staple fibres) 480 44 Spunbonds ' 250 23 Filament yarns 300 27 Spun yarns 70 6

Fibre Consumption in Tecbnical Products

Technical nonwovens Tyres Other wovens Mechillnital Rubber Goods Knits Waddings Ropes Others

% Share 59 8

13 5 3 3 3 6

Fibre Consumption in Technical Nonwovens

% Share Coverstocks 30

2.1 Nonwovens-A Major Market The most important application field for techni­

cal fibres with a share of two thirds is nonwovens (Table 2), with dry-laid nonwovens, based on sta­ple fibres, dominating the expansive spunbonds. Yam manufacture accounts for only one third of

the market for further processing to fabrics and knits .

After technical nonwovens (59%), the most im­portant markets for technical textiles are above all tyres, other wovens, mechanical rubber goods (MRG) and many other small end-use products (Table 2). Main markets for technical nonwovens are coverstocks, building end-use products and medical textiles2 (Table 2). On evaluating the fibre consumption for nonwovens, it is obtained that the largest share is held by polypropylene (44%) fol­lowed by polyester (28%), viscose (15%) and polyamide (11 %). The fibre usage in spinning de­clined by 11 % from 1987 to 1994. In a sense, nonwovens are very suitable for use in many tech­nical textiles applications, ego geotextiles, filter media, protective clothing, hospital products; the market is dominated by nonwovens. All nonwoven processes will have a main share of the develop­ment in the field of technical textiles.

3 Technical Textiles

3.1 Higb Performance Textiles The development of carbon fibres and aramid

fibres in 1960s triggered many developments in high performance fibres and yams. Today, we have access to a wide variety of fibres and yams show­ing the appropriate characteristics required for producing high-tech textiles. These include high moduluslhigh tenacity, heat resistance and stability to chemicals even at elevated temperatures.

The effects of different engineering and tech­nological parameters on mechanical properties of high-modulus and high-strength polymer fibres and yams are very important when designing tech­nical textiles and composites. This explains the

Eng./construction 24 application of mathematical models that predict W~ 9 Medical 8 the mechanical properties of yams by using the Filtration 5 data on m€?chanical properties of monofilaments, Substrates 5 yam characteristics, and manufacturing process Other techno end uses 19 parameters. Such models would make it possible to

_S_o_u_rc_e_: C_IRF~S..:.., _B_ru_s_se_ls _____________ design yams with specified mechanical properties

216 INDIAN J. FIBRE TExt. RES., DECEMBER 1997

without conducting laborious and expensive ex­perimental studies. A number of studies have been conducted in this direction in recent years3.4. Fur­ther efforts in developing mathematical models that make it possible to predict the mechanical characteristics: especially the elastic modulus of twisted yams, are worthwhile.

The range and volume of coated and laminated fabrics for applications such as protective clothing, leisure wear, workwear, building material and in­dustrial textiles are steadily growing because of the technical options for imparting a range of func­tionality in the products combined with the desired mechanical properties and durability.

3.2 High Functional Textiles

There has been a strong growth in development and use of high functional materials used in pro­tective clothings, surgical gowns, hospital and hy­gienic products and sportswear. The performance requirements of many apparels today demand the balance of widely different properties of drape, thermal insulation, barrier to liquids, chemicals and micro-organisms, thermal resistance, fire re­tardan~y , antistatic, stretch, physiological comfort, etc . The research in this field over the past decade has led to the commercial development of a variety of new products for high functional end uses. New technologies for producing microfibres have also contributed towards production of high-tech arti­cles. By designing . new processes for fabric prepa­ration and finishing and due to the advances in technologies for production and application of suitable polymeric membranes and surface fin­ishes, it is now possible to successfully combine the consumer requirements of aesthetics, design and function in protective clothing for different end-use applications.

Subsequent to the development of value-added textile products in 1970s that involved mostly di-

and with high thermal insulation at low thickne~ values. These fabrics are used in workwea sportswear, protective clothing, rainwear, moistur permeable, sweat-absorbing and with high therm, protection and comfort. One can say that thes products are basically compound materials wit compound functions. In many of these products th requirements of comfort and fashion have succes~

fully been integrated with segmentation in use: The seemingly contradictionary requirement ( creating a liquid barrier and breathability in hig functional fabrics has placed challenging demand on new technologies. Among the contributing fae tors responsible for successful marketing of suc products there have been advances in chemic, technology and production techniques (Table 3 for obtaining sophisticated structures of fibre~

yams and fabrics5.

3.3 Geotextiles

The determining factors for the acceptance 0

geotextiles as a normal part of civil engineering 0

geotechnical construction are the availability 0

relatively low-cost synthetics and the fibres fron renewable resources such as jute and flax . Poly propylene and polyester based materials constitutl the largest proportion of geosynthetics. The rav materials used in geotextiles are mainly synthetil polymers, viz. polyester, polyamide, polypropyl ene and polyethylene. Biodegradable material, e.g

Table 3-Examples of methods for obtaining sophisticated fibrous structures

Method Fibrous structure

Modification of exist- Hydrophilic polyester and acrylics ing polymers Antistatic nylon and polyester

Modification in the High shrinkable fibres fibre-forming stage Hollow fibres

Ultrafine fibres

versification of materials and improvements in Modification of fibre Combines filament yam (nylon,

f: fi ' h ' h h b h . and yam assemblies polyester) sur ace mlS les, t ere as een a strong growt m Tightly woven fabrics, double-knits developn-ent and use of so called high functional textiles and aJ: .arels. Since the introduction of Modification by Water and oil-repellence

surface finish Antistatic Gore-rex fabr 'c i, 1976, a very large variety of Perspiration absorption light-weight breat:able high functional fabric has

Laml'natt'on technt'que Bonding of fabrics to polymer film been develnT)ed, e' l xially in Japan. High func-tional fabrics are generally characterized as being Coating technique Coating of fabrics with micro-waterproof/moisture permeable, sweat-absorbing ________ ---!p:....:o_ro.:...u.:...s....;o_r_h:....yd_r_o'-ph_i_lic--'-po_I"-ym_e_r_la-,y_el

SHISHOO: TECHNICAL TEXTILES 217

jute, is also being used for some applications. The geotextile materials include woven, nonwoven and knitted geotextiles, polymer nets and grids, mats and composites. Structure/properties relationships in geotextiles include studies of intrinsic proper­ties, such as physical and mechanical properties, that are called properties of a geotextile in isola­tion, and geotextile properties that influence soil­geotextile interaction and durability.

Designing of geotextiles is done by following either the specifications or functions. In use, geotextiles are required to perform one or more functions and the major basic functions are drain­age/filtration, separation, stabilization and rein­forcement. The geotextiles market is dominated by the nonwoven products with a 70% share. At pres­ent, number of technical options exist for produc­ing nonwoven geotextiles from web forming through bonding and finishing.

3.4 Technical Needled Fabrics

The range of speciality products and the markets for technical needled fabric are extensive (Table 4). Needled fabrics in automotive application are used not only as interior coverings with aesthetic values but also as fuel and air filters, pac kings, dampers, etc . with performance value. The needled structure is an ideal media for air filtration and as particulate emission control. Needled geotextiles are the key geotextile products because of some ideal functional properties such as bulk, toughness and permeability.

3.5 Air Bags

The opportunities and challenges for the textile and making-up industries are great in the area of air bag production. This is because of its great" de­

region, Latin America and Eastern Europe. A growth ofapprox. 150% till the year 2000 has been estimated by some experts.

Air bags are usually made of coated or uncoated fabrics of PA6.6 yarns' with minimum air perme­ability. The trend towards uncoated fabrics is ex­pected to continue and so is the increased trend

Table 4-A list of needled and speciality products used in various fields

Fields

Aerospace

Agricultural

Advanced composites Industrial

Insulators, thennal barriers and fire protection Marine

Medical

Miscellaneous

Paper-making fabrics Protective clothing

Sportfelts Synthetic leather, shoefelts Wall coverings

Products

Fire blockmg fabrics , shuttle ti les and carbon fibre brake pads Ground cover, reservoirs, seed beds and erosion control Felt reinforced plastic in aerospace, pipes and transport Abrasives, roller linings, belting and substrates High-temperature glass and ceramic insulation mats, seat fire-blocking on aircraft and firewall insulation Carpets, wall coverings, headliners and surface veils for manufacturing rein­forced plastic hulls Bandages and pads, blood filters, cast bandages, artificial blood vessels and medical , hygiene and cosmetic pads Carpet underlay, car wash fabric, oil­sorbent fabrics, tree root wrap, cleaning fabrics and wipes, ink and liquid reser­voirs, weather stripping and piano felts Paper machine clothing for press felts

Ballistic materials, chain saw chaps, work gloves inserts and fire thennal barriers Tennis ball covers and floor coverings Heel and toe counters, coated fabric substrates and poromeric materials Noise abatement panels and decorative panels

mand, 'especially in view of the legalisation which Source: Techtextil Symposium, Frankfurt, June 1995 is already enforced in many countries and other -------"--!.---'----'---------countries are also going to follow this action sooner or later. Approximately 1.42 m2 of fabric is required to make a driver-side air bag, and 2.5 -4.18 m2 fabric to make passenger-side air bags or driver-side bags on light trucks. These figures point out that the air bag market is of great impor­tance for the use of technical textiles.

Figs 5 and 6 summarise development trends of air bags in Western Europe and world-wide in­cluding USA, Western Europe, Japan, Asia-Pacific

WI 25 -+- Drive'rsideo ~ Passe'ngeorsideo

go 20 -r Total ..0

-E ~ 15 .. 0 0:: -= 10 't:IE c ~ 5 ___ ~r-., c OL-____ L-____ ~ ____ ~ ____ ~ ____ ~ __ ~

1991, 1995 1996 1997 1996 1999 2000 Yeoar

Fig. 5--Demand for air bags in Western Europe

218 INDIAN J. FIBRE TEXT. RES. , DECEMBER 1997

; V) 70 ~D"iY~r ___ PQSs.f'n9e'''-'- Total E g 60 0.-

.; == 50 crE ~ ,; 40 o 0>

- ~ 30 "0

~~ 20=-_-

~; 10

o ~ OL_-.lL-_--l __ --1. __ --L::---_=:---==~ 1998 1999 2000 1994 1995 !996 1997

Yt'or

Fig. 6--Worldwide demand of equipment with air bags

towards more air bags per car and full-size bags. There is also technical challenge of manufacturing the bag using more rational techniques and ac­cording to· the tough specifications formulated by the automotive industry.

3.6 Multiaxial Differentially Oriented Structures (DOS)

Multiaxial differentially oriented structures (DOS) made using either Karl Mayer's warp­knitted based method with variations in axially orientation of construction yarns or LIBA's method of multiple weft-yarn stations give very interesting possibilities of producing technical textiles for a number of end-use applications (Figs 7-9). Karl Mayer's DOS incorporating thermoplastic yarns or split-films as matrix material has been used to pro­duce high performance composites. This material

is also suitable as substrate for coated products, and this technology allows incorporating nonwov­ens and other cellulose based materials for intro­ducing bulk in these structures. Because the inlaid yarns in DOS are placed straight without any built­in crimp, the resultant stress distribution is an in­teresting factor in designing products for different applications where load-bearing aspect is impor­tant.

3.7 Composites A composite portfolio on the basis of market

volume and price IS shown in Fig. 10. In recent years, the uses of textile struc­tures made from high performance fibres are find­ing increasing applications in composites. High performance textile structures may be defined as materials that are highly engineered fibrous struc­ture having high specific strength and specific modulus and designed to perform at high tem-

[a)

&.-O·~~:;tl~~le:/~ Fig. 7-Multiaxial DOS (Karl Mayer) [a--face, and b-side

view]

'~ ________________ ~l ~

Fig. 8--{a) Warp knit structure--inlaid weft yam lies abso­lutely straight, and (b) woven structure--weft yam bent due to intertwining with warp yams

Fig. 9-Multiaxial DOS (LlBA): 5 weft yam stations and warp yam

Fig. I O---Composites portfolio

SHISHOO: TECHNICAL TEXTILES 219

perature and pressure (loads) under corrosive and extreme environmental conditions.

Significant developments have taken place in fibres, matrix polymers and composites manufac­turing techniques. The textile manufacturing proc­esses are less complex than injection moulding and laminating, and they have advantages in greater control of fibre placement and in ease of handling preforms. These textile structures may be planar 2-D fabrics, e.g. woven, knitted or nonwoven materi­als, and 3-D fabrics, e.g. woven, braided, non­woven or knitted. Making use of the unique com­bination of light weight, flexibility, strength and toughness, textile structures have long been recog­nised as an attractive reinforcement form for many composite applications. The advantages of textile techniques are homogeneous distribution of matrix and reinforcing fibres, high drapability, free of solvents, and low financial expenditure.

As a route to mass production of textile com­posites, the production speed, material handling, CAE, material design flexibility and cost effi­ciency are some of the major factors determining the suitability of a textile reinforcement production process such as weaving, warp knitting, braiding or nonwoven technology for a given end-use applica­tion. The use of thermoset matrices is wide spread at present. The resin is applied to the textile pre­form at the consolidation stage. Polyesters or ep­oxy matrices are applied by resin transfer mould­ing (RTM) process. Faster cure is possible with other resin formulation, mainly polyurethanes, suitable for reaction injection moulding (RIM) process. From the .manufacturing point of view, however, the rational composite production proc­ess should be based on thermoplastic matrices which can be incorporated in the textile structure by the textile industry.

There has been a steady growth in the world­wide advanced composites shipments in the last decade as seen in the sales of fibres and prepregs consumed. The structure of the advanced compos­ite industry today consists of fibre supplier, resin supplier, fabric manufacturer, independent makers of prepregs, fabricated parts manufacturer and the end user. The possible new structure of composite industry based on textile technology could be the textile industry as the supplier of reinforcing and matrix fibres or split-films, on-the-Ioom prepreg-

Table 5--Comparison between thermoplastic and thermoset­ting polymers

Thermoplast <" Properties > Thermoset

Unlimited Storage time Limited Difficult Impregnation State of art No Solvents needed Yes Mostly high Viscosity Low Minutes Processing time Hours Low Water absorption High Depends on polymer Creep Low Good Impact behaviour Bad Possible Weldability Not possible Possible Recycling Not possible

Table &'-Properties of thermoplastic polyaromatic fibres

Fibre Temp.,oC Proces-T.jTm sing

temp.,oC

PEK 144/334 240 PPS 89/285 190 PEl 225/- 170 LCP -/322 180 PET 69/257 150

Maximal strength

gpd Ksl

7.5 125 5.7 90 3.5 45 27 450

9.6 165

LOI

28 34 45 35 21

ger and the fabricator. This of course becomes a realistic approach given the fact that the matrix is composed of thermoplastic polymers as compared to thermosetting polymers. A comparison of some important properties between thermoplastic and thermosetting polymers is shown in Table 5.

The textile industry now has access to multi­filament with high tensile strength and modulus and high resistance to chemical, heat and hydroly­sis for use in high performance applications and in aggressive environment (Table 6). Some of these materials can be used as matrix materials such as the more conventional polyolefin based filaments. The aromatic thermoplastic fibres of varying melt viscosity can be selected either as meltable matrix fibre or as reinforcing fibre of high tenacity (Fig. 11). Because of a marked glass transition tem­perature in some of these polyaromatic fibres, it is also possible to produce the necessary deforma­tions at prepreg stage of component manufacture. The market volume of the high performance com­posites is directly related to their price. Production of prepregs made from reinforcing fibres and thermoplastic matrix fibres with textile technolo­gies is shown in Fig. 12.

220 INDIAN 1. FIBRE TEXT. RES., DECEMBER 1997

low melt \'iscosity high

PEE K

m.urix fihn:

hi~h or "«trOlal h:n .. cit~

Fig. II-Application of aromatic thermoplastic fibres

• lommlng,hnJ:

• ( "spln",n~

'--__ ~----I

( 0 \\ rapping .~

thhrHt~iu"~-=-- =1 =====~-=--~ Fig. 12-Production of prepregs from reinforcing fibres and thermo'plastic matrix fibres

The impregnation techniques for thermoplastic composites include film stacking, melt-extrusion, melt pultrusion, solvent impregnation, powder im­pregnation and various textile forming techniques. The advantages of texti Ie techniques over the other techniques are homogeneity of matrix and rein­forcing fibres , high drapability and solvent-free process. The production of prepregs made from reinforcing fibres and thermoplastic matrix fibres with textile technologies will be in the form of hy­brid yams or hybrid fabrics. This opens up a new field of technical application by new types of semi­finished materials produced by the textile industry. Of course, quite a lot of scientific work still needs to be carried out in order to understand the mecha­nisms involving matrix-flow and fibre-matrix compatibility as regards bond strength. This knowledge is of great importance for the optimisa­tion of processing times for composites, a factor which has proven to be the determining factor for market growth of composites.

4 Technology and Material Trends The driving technological force in technical

textiles has thus far been materials development spear headed by advances in fibres , polymers and chemical technology. The mechanical processing has not played an important role so far in the serise

that very few non-conventional and technical tex­tile specific machinery have been put in the mar­ket. The conventional spinning, weaving, knitting and nonwoven techniques have been used for pro­ducing the majority of items. The coating technol­ogy used is also that which is applicable to apparel and household textiles. This means that in terms of technology, the industry is very flexible in its abil­ity to switch from conventional textiles to techni­cal textiles.

Technology advances in the industry are driven by the forces outside the pure textile sector i.e. polymer and fibre producers and, in some cases, the machinery producers of fabric fabrication tech­niques. There is a growing need for non-textile application know-how in many segments of the technical textiles market. Textile technologists, for example, are needed who understand the civil en­gineering aspects of potential geotextile applica­tions so that suitable textile structures can be pro­duced. Technologists have to understand the me­chanical and production engineering aspects of fibre composites in automotive and aeronautical applications to be able to design a suitable textile or fibre-reinforced composite components. Textile

engineers have also to start using CAD, CAM and CAE tools not only for designing the suitable tex­tile reinforcements but also to have a common lan­guagG necessary for fruitful co-operation with the design engineers working at car companies. Textile technologists do not always understand the func­tional requirements of particular application and often for textile industry the newer customers do not recognise the particular requirements of the textile company with regards to specifications, tol­erances, etc .

The equipment manufacturers are focusing on technical textiles but mostly using the conventional technology. There is realisation that the field offers growth possibilities and that completely new tech­nologies specifically for technical textiles are not needed. R&D of machinery is addressing to the problems of productivity, quality and envirol1-mental loading. One can say that the technical tex­tiles industry is using the front line technologies available but finding advanced solutions to achieve their goals.

The manufacturing, usage and disposal of tech­nical textiles are now under close inspection be-

SHISHOO: TECHNI CAL TEXTILES 221

cause of ever increasing environmental legislation. In their long-term commitment to the technical textiles industry, the manufacturers and suppliers of fibres,. polymers and chemicals are consolidat­ing their efforts to look for ways and means in which they can reduce the environmental impact of the production processes, products and consumer products in end-use applications. The environ­mental issues related to the production, use and waste management of technical products pose a challenge to the technology that is possible today. Technological developments have to be continued to reduce the pollution with various chemical and physical processes in order to reduce the hazardous substances in both air and water.

At present, the factory waste amounts to be at unnecessary high levels. This waste is simply too good to throwaway and increasing attention is being paid by technical textile producers to find new ways of recycling it. Work is being carried out on many chemical processes. An important aspect of this work is to analyse the properties 01 the resulting secondary raw materials from the chemical recycling processes. Can they offer the same performance as primary raw materials or is there a loss of quality or can their properties be improved with the help of additives and compati­bilizers? Depending on the performance profile of the recycled or reclaimed material, the appropriate area of application can be determined.

The growing public interest in environmental is­sues has led to development of different methods for the assessment of the environmental impacts from materials, products, processes and waste management techniques. Life cycle analysis of materials and products, which helps the producers of technical textiles in appropriate product and process design, is undoubtedly going to be used as an important marketing strategy.

The use of renewable cellulosic natural fibres as reinforcing fillers in fibre composites or adding a fibre blend in technical textiles products is ap­pealing because of the properties of the resultant composites and the environment viewpoint. The advantages of bio-fibres as low cost and renewable biodegradable raw materials can be utilised in some technical textile products to a much greater extent than it's being done today.

References I David Rigby Associates, Presentation at Techtextil lOI/ ­

Jerel/ce. Frankfurt, May 1997. 2 Chemical Fibres Internatiol/al, 47 (February) (1997) 8. 3 Davydov A R, Shishoo R & Prut E Y, Analysis of model s

describing the mechanical properties of yarns made of high-strength high-modulus filaments , PolYIII Sci fA}. 38(9) (1996) 1648-1053 .

4 Hearlc J W S, Grosberg P & Backer S, Stn/ctl/ral 111('­

chanics oj fibers. yams al/d Jabrics (Wiley, New York).

1969. 5 Shishoo R, Technology for comfort, Text Asia, 6 (1988).