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).