CONTRIBUTION OF TEXTILE TECHNOLOGY TO THE DEVELOPMENT OF MODERN COMPRESSED BANDAGES


Bandage
Bandage (Photo credit: Wikipedia)

 

BY: – SVETLANA MILOSAVLJEVIC & PETAR SKUNDRIC

 

Although compression therapy is a key factor in the  successful treatment of some circulatory problems in lower limbs, this form of therapy includes some risks if used inappropriately. Based on deliberate application of pressure to a lower limb, using a variety of textile materials, elastic or rigid in order to produce a desired clinical effects,  modern compression therapy presents a good sample of successful penetration of textile technology into the phlebology field of medicine. However, although compression therapy has been in use for over 150 years, there exists a low awareness among practitioners and patients on the product usage, application techniques and benefit of appropriate selection of bandages for determined types of leg venous diseases. Also, not all manufacturers for compression textile materials seem to be conscious of end-users need. simultaneously, impressive developments in the field of elastic fibers and modern knitting and weaving technologies, offer chances for realization of completely new types of compressed bandages, capable of making an important contribution to the management of venous disease. In this review, starting from brief account of pathogenesis and the presentation of compression therapy principle, an account of the contribution of all sectors in the textile technology chain to a modern compression therapy is given.

 

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contribution of TT to the development of modern compression bandages

 

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CARPET HANDBOOK


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BY – EGE

INTRODUCTION

As a skilled designer, architect, specifier, facility manager or enduser, it is important to make informed decisions when specifying carpets for a project in order to create a visually pleasing and long-lasting interior environment.

The purpose of this handbook is to provide you with the fundamentals of how carpets are made, specified, installed and maintained. In addition, aspects such as indoor climate benefits and issues related to environmental management are presented – all the basic information needed to make informed carpet decisions.

To download your copy please click the below link.

CARPET HANDBOOK

CO2 technology for water free dyeing………….


CO2 Technology

People are more familiar with the practical uses of carbon dioxide (CO2) than they realize. CO2 is the same stuff that puts the fizz in your soda at every restaurant, and dry ice is nothing more than the solid form of carbon dioxide.

CO2 can exist as a gas, solid, liquid or supercritical fluid, depending on pressure and temperature. We develop applications which use CO2 in its liquid or supercritical states.

As a solvent CO2 has gas-like viscosity and liquid-like density. It’s low surface tension and high diffusivity allow for exceptional penetration and material / particle transportation properties. It’s gentle processing is ideal for delicate or sensitive materials.

CO2 is becoming a key commercial and industrial solvent, largely due to its highly effective solvency powers and low environmental impact. Alternative solvents, such as hazardous chemicals or water, are rapidly being phased out. CO2 is the 21st century solvent.

No new CO2 is generated from our processes. We use CO2 that’s already there – it’s been recaptured from other industrial processes and recycled, so there is zero greenhouse gas effect. CO2 is non-toxic, non-hazardous, non-flammable, in-exhaustible and inexpensive. It leaves no residues or secondary wastes behind after processing and and has zero potential for soil or groundwater contamination. In most cases process costs are lower than comparable conventional processes.

Our solutions are implemented across the processing spectrum, including the food, pharmaceutical, flavors & fragrances, renewable energies and textiles sectors. Here’s a few of the most exciting successes:

Dyeing Textiles Without Water
The textile industry is believed to be one of the biggest consumers of water. In conventional textile dyeing large amounts of water are used, both in terms of intake of fresh water and disposal of waste water. On average an estimated 11 – 14 gallons of, otherwise drinkable, water is needed to process 1 lb of textile. FeyeCon, together with partners, developed a process to dye textiles with CO2. It’s a completely water-free dyeing process with considerably lower operational costs compared to conventional dyeing processes.
For more information visit www.dyecoo.com

Fast Diagnoses Without Toxic Solvents
In medicine certain diseases are detectable only through the sampling and testing of tissue. Conventional tissue processing techniques rely on the use of toxic chemicals and is an overnight process. FeyeCon developed a process that eliminates the need for hazardous chemicals and processes quick enough for same-day diagnosis. Laboratory staff are not exposed to toxic chemicals, no hazardous wastes are produced, laboratory efficiency is increased and patients get fast results – unprecedented improvements in histological processing.
For more information visit www.tispamedical.com

Clean Clothes, Clean Environment
Cleaning clothes, professional garments and other textile are traditionally water and/or chemical intense. “Eco friendly” and “organic” cleaning solutions have been marketed recently, none of them however are truly sustainable. Together with partners FeyeCon has developed the next generation of fabric and textile cleaning methods that use liquid CO2 as a cleaning solvent. Washing is gentle and requires no heat (to wash or dry), which translates into longer lasting garments. No water, no toxic chemicals – just clean clothes.
For more information visit www.co2nexus.com

Health effects of Man-made fibers


Clara S. Ross, James E. Lockey

The industrial use of various types of man-made fibres has been increasing, particularly since restrictions were placed on the use of asbestos in view of its known health hazards. The potential for adverse health effects related to the production and use of man-made fibres is still being studied. This article will provide an overview of the general principles regarding the potential for toxicity related to such fibres, an overview of the various types of fibres in production (as listed in table 1) and an update regarding existing and ongoing studies of their potential health effects.

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Table 1    Synthetic fibres

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Toxicity Determinants

The primary factors related to potential for toxicity due to exposure to fibres are:

1. fibre dimension

2. fibre durability and

3. dose to the target organ.

Generally, fibres that are long and thin (but of a respirable size) and are durable have the greatest potential for causing adverse effects if delivered to the lungs in sufficient concentration. Fibre toxicity has been correlated in short-term animal inhalation studies with inflammation, cytotoxicity, altered macrocyte function and biopersistence. Carcinogenic potential is most likely related to cellular DNA damage via formation of oxygen-free radicals, formation of clastogenic factors, or missegregation of chromosomes in cells in mitosis-alone or in combination. Fibres of a respirable size are those less than 3.0 to 3.5 in diameter and less than 200 in length. According to the “Stanton hypothesis,” the carcinogenic potential of fibres (as determined by animal pleural implantation studies) is related to their dimension (the greatest risk is associated with fibres less than 0.25 in diameter and greater than 8 in length) and durability (Stanton et al. 1981). Naturally occurring mineral fibres, such as asbestos, exist in a polycrystalline structure that has the propensity to cleave along longitudinal planes, creating thinner fibres with higher length-to-width ratios, which have a greater potential for toxicity. The vast majority of man-made fibres are non-crystalline or amorphous and will fracture perpendicularly to their longitudinal plane into shorter fibres. This is an important difference between asbestos and non-asbestos fibrous silicates and man-made fibres. The durability of fibres deposited in the lung is dependent upon the lung’s ability to clear the fibres, as well as the fibres’ physical and chemical properties. The durability of man-made fibres can be altered in the production process, according to end-use requirements, through the addition of certain stabilizers such as . Because of this variability in the chemical constituents and size of man-made fibres, their potential toxicity has to be evaluated on a fibre-type by fibre-type basis.

Man-made Fibres

Aluminium oxide fibres

Crystalline aluminium oxide fibre toxicity has been suggested by a case report of pulmonary fibrosis in a worker employed in aluminium smelting for 19 years (Jederlinic et al. 1990). His chest radiograph revealed interstitial fibrosis. Analysis of the lung tissue by electron microscopy techniques demonstrated crystalline fibres per gram of dry lung tissue, or ten times more fibres than the number of asbestos fibres found in lung tissue from chrysotile asbestos miners with asbestosis. Further study is needed to determine the role of crystalline aluminium oxide fibres (figure 1) and pulmonary fibrosis.

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Figure 1    Scanning electron micrograph (SEM) of aluminium oxide fibres

Courtesy of T. Hesterberg.

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This case report, however, suggests a potential for fibrization to take place when proper environmental conditions coexist, such as increased air flow across molten materials. Both phase-contrast light microscopy and electron microscopy with energy dispersion x-ray analysis should be used to identify potential airborne fibres in the work environment and in lung tissue samples in cases where there are clinical findings consistent with fibre-induced pneumoconiosis.

Carbon/Graphite Fibres

Carbonaceous pitch, rayon or polyacrylonitrile fibres heated to 1,200 form amorphous carbon fibres, and when heated above 2,200 form crystalline graphite fibres (figure 2). Resin binders can be added to increase the strength and to allow moulding and machining of the material. Generally, these fibres have a diameter of 7 to 10 , but variations in size occur due to the manufacturing process and mechanical manipulation. Carbon/graphite composites are used in the aircraft, automobile and sporting goods industries. Exposure to respirable-sized carbon/graphite particles can occur during the manufacturing process and with mechanical manipulation. Furthermore, small quantities of respirable-sized fibres can be produced when composites are heated to 900 to 1,100 . The existing knowledge regarding these fibres is inadequate to provide definite answers as to their potential for causing adverse health effects. Studies involving intratracheal injection of different graphite fibre composite dusts in rats produced heterogeneous results. Three of the dust samples tested produced minimal toxicity, and two of the samples produced consistent toxicity as manifested by cytotoxicity for alveolar macrophages and differences in the total number of cells recovered from the lung (Martin, Meyer and Luchtel 1989). Clastogenic effects have been observed in mutagenicity studies of pitch-based fibres, but not of polyacrylonitrile-based carbon fibres. A ten-year study of carbon fibre production workers, manufacturing fibres 8 to 10 mm in diameter, did not reveal any abnormalities (Jones, Jones and Lyle 1982). Until further studies are available, it is recommended that exposure to respirable-sized carbon/graphite fibres be 1 fibre/ml (f/ml) or lower, and that exposure to respirable-sized composite particulates be maintained below the current respirable dust standard for nuisance dust.

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Figure 2   SEM of carbon fibres

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Kevlar para-aramid fibres

Kevlar para-aramid fibres are approximately 12 in diameter and the curved ribbon-like fibrils on the surface of the fibres are less than 1 in width (figure 3). The fibrils partially peel off the fibres and interlock with other fibrils to form clumps which are non-respirable in size. The physical properties of Kevlar fibres include substantial heat resistance and tensile strength. They have many different uses, serving as a reinforcing agent in plastics, fabrics and rubber, and as an automobile brake friction material. The eight-hour time-weighted average (TWA) of fibril levels during manufacturing and end-use applications ranges from 0.01 to 0.4 f/ml (Merriman 1989). Very low levels of Kevlar aramid fibres are generated in dust when used in friction materials. The only available health effects data is from animal studies. Rat inhalation studies involving one- to two-year time periods and exposures to fibrils at 25, 100 and 400 f/ml revealed alveolar bronchiolarization which was dose-related. Slight fibrosis and alveolar duct fibrotic changes also were noted at the higher exposure levels. The fibrosis may have been related to overloading of pulmonary clearance mechanisms. A tumour type unique to rats, cystic keratinizing squamous cell tumour, developed in a few of the study animals (Lee et al. 1988). Short-term rat inhalation studies indicate that the fibrils have low durability in lung tissue and are rapidly cleared (Warheit et al. 1992). There are no studies available regarding the human health effects of exposure to Kevlar para-aramid fibre. However, in view of the evidence of decreased biopersistence and given the physical structure of Kevlar, the health risks should be minimal if exposures to fibrils are maintained at 0.5 f/ml or less, as is now the case in commercial applications.

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Figure 3    SEM of Kevlar para-aramid fibres

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Silicon carbide fibres and whiskers

Silicon carbide (carborundum) is a widely used abrasive and refractory material that is manufactured by combining silica and carbon at 2,400 . Silicon carbide fibres and whiskers-figure 4 (Harper et al. 1995)-can be generated as by-products of the manufacture of silicon carbide crystals or can be purposely produced as polycrystalline fibres or monocrystalline whiskers. The fibres generally are less than 1 to 2  in diameter and range from 3 to 30 in length. The whiskers average 0.5 in diameter and 10 in length. Incorporation of silicon carbide fibres and whiskers adds strength to products such as metal matrix composites, ceramics and ceramic components. Exposure to fibres and whiskers can occur during the production and manufacturing processes and potentially during the machining and finishing processes. For example, short-term exposure during handling of recycled materials has been shown to reach levels up to 5 f/ml. Machining of metal and ceramic matrix composites have resulted in eight-hour TWA exposure concentrations of 0.031 f/ml and up to 0.76 f/ml, respectively (Scansetti, Piolatto and Botta 1992; Bye 1985).

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Figure 4    SEMs of silicon carbide fibres (A) and whiskers (B)

A

B

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Existing data from animal and human studies indicate a definite fibrogenic and possible carcinogenic potential. In vitro mouse cell culture studies involving silicon carbide whiskers revealed cytotoxicity equal to or greater than that resulting from crocidolite asbestos (Johnson et al. 1992; Vaughan et al. 1991). Persistent adenomatous hyperplasia of rat lungs was demonstrated in a subacute inhalation study (Lapin et al. 1991). Sheep inhalation studies involving silicon carbide dust revealed that the particles were inert. However, exposure to silicon carbide fibres resulted in fibrosing alveolitis and increased fibroblast growth activity (Bйgin et al. 1989). Studies of lung tissue samples from silicon carbide manufacturing workers revealed silicotic nodules and ferruginous bodies and indicated that silicon carbide fibres are durable and can exist in high concentrations in lung parenchyma. Chest radiographs also have been consistent with nodular and irregular interstitial changes and pleural plaques.

Silicon carbide fibres and whiskers are respirable in size, durable, and have definite fibrogenic potential in lung tissue. A manufacturer of silicon carbide whiskers has set an internal standard at 0.2 f/ml as an eight-hour TWA (Beaumont 1991). This is a prudent recommendation based on currently available health information.

Man-made Vitreous Fibres

Man-made vitreous fibres (MMVFs) generally are classified as:

1. glass fibre (glass wool or fibreglass, continuous glass filament and special-purpose glass fibre)

2. mineral wool (rock wool and slag wool) and

3. ceramic fibre (ceramic textile fibre and refractory ceramic fibre).

The manufacturing process begins with melting raw materials with subsequent rapid cooling, resulting in the production of non-crystalline (or vitreous) fibres. Some manufacturing processes allow for large variations in terms of fibre size, the lower limit being 1 or less in diameter (figure 5). Stabilizers (such as , and ZnO) and modifiers (such as MgO,  , BaO, CaO, and ) can be added to alter the physical and chemical properties such as tensile strength, elasticity, durability and thermal non-transference.

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Figure 5    SEM of slag wool

Rock wool, glass fibres and refractory ceramic fibres are identical in appearance

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Glass fibre is manufactured from silicon dioxide and various concentrations of stabilizers and modifiers. Most glass wool is produced through use of a rotary process resulting in 3 to 15 average diameter discontinuous fibres with variations to 1 or less in diameter. The glass wool fibres are bound together, most commonly with phenolic formaldehyde resins, and then put through a heat-curing polymerization process. Other agents, including lubricants and wetting agents, may also be added, depending on the production process. The continuous glass filament production process results in less variation from the average fibre diameter in comparison to glass wool and special-purpose glass fibre. Continuous glass filament fibres range from 3 to 25 in diameter. Special-purpose glass fibre production involves a flame attenuation fibrization process that produces fibres with an average diameter of less than 3 .

Slag wool and rock wool production involves melting and fibrizing slag from metallic ore and igneous rock, respectively. The production process includes a dish shaped wheel and wheel centrifuge process. It produces 3.5 to 7 average diameter discontinuous fibres whose size may range well into the respirable range. Mineral wool can be manufactured with or without binder, depending on end-use applications.

Refractory ceramic fibre is manufactured through a wheel centrifuge or steam jet fibrization process using melted kaolin clay, alumina/silica, or alumina/silica/zirconia. Average fibre diameters range from 1 to 5 . When heated to temperatures above 1,000 , refractory ceramic fibres can undergo conversion to cristobalite (a crystalline silica).

MMVFs with different fibre diameters and chemical composition are used in over 35,000 applications. Glass wool is used in residential and commercial acoustical and thermal insulation applications, as well as in air handling systems. Continuous glass filament is used in fabrics and as reinforcing agents in plastics such as are employed in automobile parts. Special-purpose glass fibre is used in specialty applications, for instance in aircraft, that require high heat and acoustical insulation properties. Rock and slag wool without binder is used as blown insulation and in ceiling tiles. Rock and slag wool with a phenolic resin binder is used in insulation materials, such as insulation blankets and batts. Refractory ceramic fibre constitutes 1 to 2% of the worldwide production of MMVF. Refractory ceramic fibre is used in specialized high-temperature industrial applications, such as furnaces and kilns. Glass wool, continuous glass filament and mineral wool are manufactured in the greatest amounts.

MMVFs are thought to have less potential than naturally occurring fibrous silicates (such as asbestos) for producing adverse health effects because of their non-crystalline state and their propensity to fracture into shorter fibres. Existing data suggests that the most commonly utilized MMVF, glass wool, has the lowest risk of producing adverse health effects, followed by rock and slag wool, and then both special-purpose glass fibre with increased durability and refractory ceramic fibre. Special-purpose glass fibre and refractory ceramic fibre have the greatest potential for existing as respirable-sized fibres as they are generally less than 3 in diameter. Special-purpose glass fibre (with increased concentration of stabilizers such as ) and refractory ceramic fibre are also durable in physiologic fluids. Continuous glass filaments are non-respirable in size and therefore do not represent a potential pulmonary health risk.

Available health data is gathered from inhalation studies in animals and morbidity and mortality studies of workers involved with MMVF manufacturing. Inhalation studies involving exposure of rats to two commercial glass wool insulation materials averaging 1 in diameter and 20 in length revealed a mild pulmonary cellular response which partly reversed following discontinuation of exposure. Similar findings resulted from an animal inhalation study of a type of slag wool. Minimal fibrosis has been demonstrated with animal inhalation exposure to rock wool. Refractory ceramic fibre inhalation studies resulted in lung cancer, mesothelioma and pleural and pulmonary fibrosis in rats and in mesothelioma and pleural and pulmonary fibrosis in hamsters at a maximum tolerated dose of 250 f/ml. At 75 f/ml and 120 f/ml, one mesothelioma and minimal fibrosis was demonstrated in rats, and at 25 f/ml, there was a pulmonary cellular response (Bunn et al. 1993).

Skin, eye, and upper and lower respiratory tract irritation can occur and depends on exposure levels and job duties. Skin irritation has been the most common health effect noted and can cause up to 5% of new MMVF manufacturing plant workers to leave their employment within a few weeks. It is caused by mechanical trauma to the skin from fibres greater than 4 to 5 in diameter. It can be prevented with appropriate environmental control measures including avoiding direct skin contact with the fibres, wearing loose fitting, long-sleeved clothing, and washing work clothing separately. Upper and lower respiratory symptoms can occur in unusually dusty situations, particularly in MMVF product fabrication and end-use applications and in residential settings when MMVFs are not handled, installed or repaired correctly.

Studies of respiratory morbidity, as measured by symptoms, chest radiographs and pulmonary function tests among manufacturing plant workers generally have not found any adverse effects. However, an ongoing study of refractory ceramic fibre manufacturing plant workers has revealed an increased prevalence of pleural plaques (Lemasters et al. 1994). Studies in secondary production workers and end-users of MMVF are limited and have been hampered by the likelihood of the confounding factor of previous asbestos exposures.

Mortality studies of workers in glass fibre and mineral wool manufacturing plants are continuing in Europe and the United States. The data from the study in Europe revealed an overall increase in lung cancer mortality based upon national, but not local, mortality rates. There was an increasing trend of lung cancer in the glass and mineral wool cohorts with time since first employment but not with duration of employment. Using local mortality rates, there was an increase in lung cancer mortality for the earliest phase of mineral wool production (Simonato, Fletcher and Cherrie 1987; Boffetta et al. 1992). The data from the study in the United States demonstrated a statistically significant increased risk of respiratory cancer but failed to find an association between the development of cancer and various fibre exposure indices (Marsh et al. 1990). This is in accord with other case-control studies of slag wool and glass fibre manufacturing plant workers which have revealed an increased risk of lung cancer associated with cigarette smoking but not to the extent of MMVF exposure (Wong, Foliart and Trent 1991; Chiazze, Watkins and Fryar 1992). A mortality study of continuous glass filament manufacturing workers did not reveal an increased risk of mortality (Shannon et al. 1990). A mortality study involving refractory ceramic fibre workers is under way in the United States. Mortality studies of workers involved with product fabrication and end-users of MMVF are very limited.

In 1987, the International Agency for Research on Cancer (IARC) classified glass wool, rock wool, slag wool, and ceramic fibres as possible human carcinogens (group 2B). Ongoing animal studies and morbidity and mortality studies of workers involved with MMVF will help to further define any potential human health risk. Based on available data, the health risk from exposure to MMVF is substantially lower than what has been associated with asbestos exposure both from a morbidity and mortality perspective. The vast majority of the human studies, however, are from MMVF manufacturing facilities where exposure levels have generally been maintained below a 0.5 to 1 f/ml level over an eight-hour work day. The lack of morbidity and mortality data on secondary and end-users of MMVF makes it prudent to control respirable fibre exposure at or below these levels through environmental control measures, work practices, worker training and respiratory protection programmes. This is especially applicable with exposure to durable refractory ceramic and special purpose glass MMVF and any other type of respirable man-made fibre that is durable in biological media and that can therefore be deposited and retained in the pulmonary parenchyma.

Ref:-http://www.ilo.org/safework_bookshelf/english?content&nd=857170112