Messages

1

Textile Dyeing / Functional (high technology) dyes and pigments

« on: November 28, 2018, 01:32:09 AM »

Functional dyes and pigments are produced in small volumes compared to compounds used for dyeing textiles. However, they are the subject of much research and interest and are being developed for a variety of purposes. Some of these are illustrated below.

(a) Liquid crystal displays
Liquid crystals have played an important part in our lives for many years in various forms of information displays e.g. calculators. Initially they could only display differences between light and dark. It was found that by using dyes this contrast could be increased and coloured screens produced. They have now largely replaced the traditional display technologies of light emitting diodes and cathode ray tubes. The dyes used have been specifically designed to change orientation with the liquid crystal molecules and therefore offer a higher intensity of colour. These dyes are said to exhibit dichroism.

(b) Laser dyes
The term laser is an acronym referring to light amplification by stimulated emission of radiation.

Commonly inorganic lasers were used but only had the ability to produce radiation at a few selected wavelengths and in very narrow bands. The use of dyes has allowed for the production of light throughout the spectrum from wavelengths of 320 to 1200 nm. The application of dye lasers includes communication technology, and microsurgery.

(c) Ink jet printing
Ink jet printing is a non-impact technique to produce images by directing small droplets of ink, ideally under computer control, in rapid succession onto a substrate. It has found many applications. Because of the size requirements for the droplets to be able to achieve good definition the use of dyes has been favoured over pigments. Droplets are smaller (pigments tend to block the nozzles) and aqueous solubility reduces the environmental impact and keeps the price low. Early dyes were those already used in other industries but were characterized by poor water fastness. This has led to the development of specific dyes and unique fluid systems. These dyes are designed to be soluble in slightly alkaline systems (pH 7.5 to 10) which are made insoluble by the slightly acidic conditions (pH 4.5 to 6.5) on the paper or other substrate. This technology is having a great impact on high volume industrial printing for packaging, textiles, wallcoverings and advertising displays.

(d) Photodynamic therapy
This is a treatment for cancer that uses a combination of laser light, a photosensitizing compound (the dye) and molecular oxygen. The dye is administered to the patient intravenously and over time enters the cancerous cells. Irradiation of the cells with laser light can start their destruction.

The laser interacts with the dye and promotes it to its excited state. Through a complex process, excited (more reactive) oxygen molecules are produced which react with unsaturated centres in the proteins and lipids in the cell membrane. This method of treatment avoids the use of invasive surgery.

 

2

Textile Finishing / Recent trends in easy care finishing -part 3

« on: November 22, 2018, 11:53:30 AM »

Recent trends:

(a) Low or ultra low formaldehyde easy care finishing:

Washing of cured fabric reduces the chances of released formaldehyde from the finished fabric.
Washing removes free formaldehyde as well as untreated N-mehylol groups which may decompose to form formaldehyde. The PH during washing plays an important role in the formaldehyde release properties of finished fabrics. Generally the PH range for best formaldehyde release properties is between PH 4 to PH 5 (11). The temperature of the wash bath has little or no effect on the amount of formaldehyde released from DMDHEU finished fabrics, consequently a low temperature or room temperature washing is preferable. A considerable amount of water and heat energy is needed to redry the fabric after washing which increases the production costs and this is the major draw-back of the process.

To decrease the amount of formaldehyde of the fabrics finished with N-methylol compounds, a process which is based on the spraying of urea on to the cured fabrics has been developed. The process is called the BASF fog-chamber technique. This technique is very efficient for reducing the amount of formaldehyde liberated during the storage of finished fabrics. In most cases a 10-30% solution of urea has proved satisfactory, while an atomized spray for low wet pick-up of 5-10% is sufficient.

Methylated DMDHEU reactants can reduce the formaldehyde release to an ultra-low level. A two-step
production sequence of methylated DMDHEU was developed (12). The methylated DMDHEU treated fabric has exceptional performance as evidenced by superior chlorine resistance and enhanced wash durability.

(b) Formaldehyde free easy care finishing:

Due to the increasing public awareness of formaldehyde hazards, in recent years there has been a trend to avoid the use of formaldehyde and thus to eliminate any possible formaldehyde release from the finished fabrics. The resin finishing industry has researched extensively a non-formaldehyde easy care finishing treatment to provide high quality and high safety clothing for practical use.
 Glyoxal with aluminum sulfate catalyst can impart a high degree of wrinkle resistance and smooth drying qualities to cotton fabric. A considerable amount of strength loss was observed at high curing temperature (145-155°) but by using aluminum dihyderoxy acetate as buffer the fabric can be treated with high curing temperature (145-160 °C) for 15 seconds and that imparts a very good easy care effect comparable to that of a conventional pad-dry-cure treatment with DMDHEU (13).

Among the new non formaldehyde finishes being developed, poly-carboxylic acids appear to have a number of advantages over other reagents (14). Recently a process was developed using monosodium phosphates as the curing catalyst for easy care finishing with 1, 2, 3, 4-butanetetrcarcarboxylic acid. The process is suitable for simple pad-dry-cure techniques. After padding with polycarboxylic acid, catalyst and softener, the fabrics was dried at 80°C and then cured at 180°C for 90 Seconds. The cured fabric  was rinsed in 50°C in running water for 30 minutes and finally dried at 85°C for 5 mins. The finished fabric demonstrated an excellent easy care finishing effect, a high level of smooth drying properties, good laundry durability and no yellowing effects. Breaking and tearing strength retention is somewhat higher than in DMDHEU treatment catalyzed by magnesium chloride.

More recently sodium hydrosulphite has proven to be the most active curing catalyst for easy care finishing with 1, 2, 3, 4- butaneteracarboxylic acid. By using sodium hypophosphite as catalyst it is possible to reduce the curing time to as low as 15 seconds at a temperature of 205-215°C, thus making high speed fabric finishing possible. Additives have also been found which increase the easy care finishing performance of cotton fabric treated with BTCA catalysed by hypophosphite. The addition of 2-3% N, N-disubstituted amides will produce the following effects:

Increased easy care performance
Increased durability to alkaline laundering
Decrease in the concentration of sodium hypophosphite and BTCA required and thus lower the chemical cost.
Due to the harmful effect of formaldehyde and increasing public awareness of formaldehyde hazards, BTCA could be the effective cross-linking agent for high quality cotton fabric.

3

Textile Finishing / Recent trends in easy care finishing - part 2

« on: November 22, 2018, 11:50:44 AM »

Another compound 1, 3-dimethylo-4, 5-hydroxy-2-imidazolidone, commonly known as dimethylol dihydroxyethyleneurea (DMDHEU) was introduced for cotton fabric for easy care finishing. The product is now the most widely used reactant and it cross-links cellulose in the presence of an acid catalyst. DMDHEU has no effect on light fastness of reactive dyes and there is less chance of discoloration of fabric dyed with reactive dyes. The formula below shows in simplified form, how cellulose is thought to become cross linked with DMDHEU:

2Process of cross linking:

(a) Pre-cure process:

In this process, the fabric is generally impregnated with resin precondensate and /or cross-linking reactants and catalysts. The impregnated fabric is then dried and cured at high temperature to obtain the cross-linking effect. The curing temperature and time are dependent on the types of cross-linking agents and fabrics. The sequence of pre-cure processes is as follows (2):
(i)  Impregnation.
(ii)  Drying at 80°c – 100°c temperature.
(iii) Curing at 150°c temperature for 4 – 5 minutes.
(iv) Cutting, sewing and making-up.
(v) The garments are steamed for 3 – 5 seconds, then pressed for 15 – 25 seconds at 205 – 230°c temperature at a pressure of 15 lbs/ inch.
Curing the day after drying is claimed to have a favorable influence on the fabric tensile strength and abrasion resistance properties. If the goods are to be calendered to impart luster this must be done before curing, otherwise the tensile strength will be very much impaired.

(b) Post-cure Process:
The post-cure process also known as deferred curing process is basically different from conventional finishing techniques. In this process the fabrics is impregnated with appropriate reactant, catalyst and other finishing agents and dried carefully so that no curing occurs. This uncured fabric is referred to as sensitized cloth, and after pressing to shape, they may be cured in an oven. The following temperatures are generally employed:
Pressing: 5 – 15 seconds at 120 – 165°c
Curing: 10 – 18 minutes at 170 – 190°c

The post cure process produces garments with outstanding easy care finishing properties, but several important points should be considered:

The dyed fabric, which is to be finished, should be free of size, alkali, and other impurities.
Impregnation may be preferred on a two-roll pad with a good dip box so as to provide a long dip with one nip; or on a three-roll pad to provide two dips and two nips.
The fabric must be dried under controlled conditions. The speed of the dryer should be adjusted so that the fabric leaves the frame with approximately 10% moisture based on the weight of the cotton present.
The fabric leaves the finishing plant in its uncured state and precaution must be taken to avoid premature curing. This means that the combination of resin, catalyst and other finishing agents must be very carefully selected.
Dimethylol-dihydroxy-ethyleneurea (DMDHEU) is the most suitable reagent for the post cure process due to its outstanding resistance to odor development and excellent chemical stability to prolong storage. Very reactive catalysts such as Magnesium chloride and Zinc nitrate are suitable for the post-cure process.

(c) Re-cure or Double cure Process:

This is another method of producing easy care finished fabric. This process involves the following steps:

The fabric is impregnated in the conventional way, except that the formulation contains a high boiling point non-reactive additive.
The fabric is given a first cure at a temperature below that at which the inert additive would volatilize.
The one-cured fabric is cut and sewn to produce a garment.
The second cure is given at a high temperature, during which the inert additive volatilizes.
After the first cure the cross-linking chemical is fixed within the fabric and cannot be washed out. At this stage the fabric had high wet wrinkle recovery but low dry wrinkle recovery. An interesting characteristic is that, after the second cure, the dry wrinkle recovery increases substantially while the wet wrinkle recovery does not decrease. The major draw-back of this process is the increased cost of the additive. Generally tetramethylene sulphone or the dimethyl ether of tetramethyl glycol is used for the purpose and these are very expensive.

The most important reactants for easy care finishing are the N-methylol compounds and their derivatives. They are easily applicable and low in price. Probably dimethylol dihydroxy ethylene urea (DMDHEU) is the most important reactant and is widely used because it does not produce yellowing on finished fabric (. However, recently there has been a growing concern about the problems that may be generated as a result of formaldehyde release form N-mehtylol containing compound treated cotton fabrics.

Formaldehyde and its impact:

Formaldehyde is a toxic chemical being a sever eye irritant, a mucous membrane irritant, a skin irritant and toxic if ingested . In easy care finished fabrics there are several sources capable of releasing formaldehyde. The cellulose substrate may retain some free formaldehyde reactant during the finishing process. This formaldehyde will be released during storage of the finished fabrics especially under worm and humid conditions. This would couse “formaldehyde odour” problem during the garment processing of finished fabrics which have been stored for a period of time. In addition formaldehyde may be formed via the hydrolysis of the N-hydroxymethyl groups from untreated cross linking agent or from single end reacted DMDHEU molecules. Cleavage of the C-O bond of any cross links between the cellulose and the poly-functional cross linking agent will provide additional N-hydroxymethyl groups which can hydrolyze to release formaldehyde.
From a review of several hundred references it can be summarized the effect of exposure to formaldehyde; the following table shows the summary of human inhalation data of formaldehyde:

Concentration (ppm)                   Exposure                                                 Effects
20                                        Chamber (1min)                           Discomfort, lacrimation.
13.8                                        Chamber (30 min)                    Eye and nose irritation
0.5-10                                Indoor residential air                   Eye irritation, headaches, GI tract
                                                                                                symptoms, skin roblems, respiratory
                                                                                                complaints.
4-5                                       Occupational (10-30 min)           Irritation, discomfort, lacrimation
0.67-4.82                               Indoor residential air (infants)           Vomiting, diarrhea, lacrimation.

4

Textile Finishing / Recent trends in easy care finishing - part 1

« on: November 22, 2018, 11:43:38 AM »

Cotton is a very popular textile fibre with some excellent properties, such as : comfort during wear, ease of dye ability, soft handle and with good tensile properties. However, cotton fabric has a great tendency to retain creases acquired in laundering and in use. Due to the poor crease recovery properties cotton fibre have been facing considerable competition from synthetic fibres.

In 1930, The Tootal Broadhurst Lee Co. Ltd. first disclosed details of a procedure for producing easy care finishing (crease resistant finishing) for cotton. The demands on cotton fabrics for high levels of easy care finishing have become more important in recent years and the research to improve the process is still continuing.

Easy care finishing can be expressed as a chemical modification of fibrous cellulose resulting from a heterogeneous reaction with a di-functional or poly-functional reagent which generates resilience in cotton containing fabrics by a “modus operandi” (called cross linking) which occurs in accessible regions of the fibre between hydroxyl groups on two different molecules of cellulose in unspecified locations in the microstructure.

Easy care finishes are expected to impart the following desirable properties to the fabric :


 
Uncomplicated laundering
Minimum wrinkling when dry or wet
Fast drying
No ironing necessary
Good soil-repellency and easy removal of soil by washing
Full retention of all creases and pleats
Good retention of dimensions and shape
Wearer comfort in different climates
Adequate resistance to wear and tear.

Formaldehyde in the presence of an acid catalyst is the oldest, cheapest but most destructive reagent (reduces strength) for obtaining crease resistance effects on cotton. Formaldehyde behaves as a bi-functional reagent and forms covalent cross-linkage with cellulose.

Two types of cross-linkage many be formed:

1Though formaldehyde is a cheap, efficient, cross linker, it has not found commercial success as a cross-linking agent. There are three reasons for the restricted use of formaldehyde in easy care finishing:

-The odor and toxicity of the reagent
-The variability of results
-The excessive loss of fabric strength.

Later the cyclic urea of two methyl group has developed to impart to the cotton a high degree of resistance to dry and wet creasing, good chlorine fastness, and good stability towards hydrolysis. The simplest derivatives of this groups is 1, 3-dimethylol-2-imidazolidone, commonly known as dimethylolethyleneurea (DMEU). This bi-functional product is water soluble and forms cross links with the hydroxyl groups of cellulose through N-methylol groups.

5

Textile Finishing / Nano-finishing in fabric

« on: November 17, 2018, 12:20:27 AM »

Nanotechnology has been discovered by the textile industry  – in fact, a new area has developed in the area of textile finishing called “Nanofinishing”.   Making fabric with nano-sized particles  creates many desirable properties in the fabrics without a significant increase in weight, thickness or stiffness, as was the case with previously used techniques.    Nanofinishing techniques include: UV blocking, anti-microbial, bacterial and fungal, flame retardant, wrinkle resistant, anti-static, insect and/or water repellant and self-cleaning properties.

One of the most common ways to use nanotechnology in the textile industry is to create stain and water resistance.   To do this, the fabrics are embedded with billions of tiny fibers, called “nanowhiskers” (think of the fuzz on a peach), which are waterproof and increase the density of the fabric.  The Nanowhiskers can repel stains because they form a cushion of air around each cotton fiber. When something is spilled on the surface of the fabric, the miniature whiskers actually cohesively prop up the liquid drops, allowing the liquid drops to roll off.   This treatment lasts, they say, for about 50 home wash cycles before its effectiveness is lost.  A corollary finish is that of using nanoparticles to provide a “lotus plant” effect  which causes dirt to rinse off easily, such as in the rain.

Nanotechnology can also be used in the opposite manner to increase the ability of textiles, particularly synthetics, to absorb dyes. Until now most polypropylenes have resisted dyeing, so they were deemed unsuitable for consumer goods like clothing, table cloths, or floor and window coverings. A new technique being developed is to add nanosized particles of dye friendly clay to raw polypropylene stock before it is extruded into fibres. The resultant composite material can absorb dyes without weakening the fabric.

The other main use of nanoparticles in textiles is that of using silver nanoparticles for antimicrobial, antibacterial effects,  thereby eliminating odors in fabrics.  Nanoparticles of silver are the most widely used form of nanotechnology in use today, says Todd Kuiken, PhD, research associate at the Project on Emerging Nanotechnologies (PEN). “Silver’s antimicrobial property is one that suits a lot of different products, and companies pretty much run the gamut of how many consumer products they put it in.”

6

Knitting / Re: Knit denim

« on: November 17, 2018, 12:11:38 AM »

very informative sir....
I want to add the Environmental Aspects of Woven Denim and Knit Denim...

The prospect or acceptance of any developed product only depends on cheaper production cost (conventional thinking) but also environmental effects by the product introduced. Two additional processes, namely sizing and desizing that are must in weaving process have tremendous negative impact on our environment, polluting huge amount of water and therefore, water bodies- ponds, rivers, and cannels and etc. cost of sizing chemicals and processes running on different textile machinery make the weaving process not only costlier but also carcinogenic to our life and environment.  Chemicals like Penta-chloro phenol an anti-mildew agent used in sizing process contributes to environmental pollution and therefore causes serious health hazard to human being and other living things. Knitted denim product can be that product in the future that will earn us more profit and at the same time help preserve our environment reducing as much pollution as possible.

Comparison between Woven and Knit Denims:

Historically, denims have been produced from yarn-dyed spun yarns of cotton or combinations of cotton and synthetic and synthetic blend spun yarns, which have been woven together to provide a fabric having a generally uniform appearance. These woven fabrics are typically quite stable, exhibiting little extensibility or stretch to accommodate body movement in garments made from such fabrics.When such woven fabrics include a substantial amount of cotton or other similar yarns, they are quite susceptible to wrinkling, and therefore do not provide preferred characteristics such as ease of care and a long lasting neat appearance. Knitted denim fabric having good wrinkle resistance and improved extensibility or stretch to better accommodate body movement and provide comfort.  After denim fabric knitting, the differentially colorable yarns may be dyed to selectively color one or more of the yarn groups as desired. The denim effect may be enhanced by sanding or napping the denim surface of the fabric to raise the dominant colored yarns and blend the lighter colored yarn therewith. [6]

Merits of Knit Denim [7] :
The knitted denim offers the following advantages in comparison with its woven counterpart:


-The comfort ability of knit denim garments is better than woven denim garments.
-It mold and move easily with body movement.
-Its stretch ability is good.
-It resists wrinkles.
-Most important perhaps is that knits relate well to contemporary life-styles.
-Knit fabrics are usually soft and drape well.
-Thicker fabrics compared to woven fabric which are usually thinner
-Air Permeability is more in knit fabrics

7

International Standards / Re: ISO

« on: November 17, 2018, 12:05:41 AM »

good initiative to share about ISO. I want to add some more about it specially in textile sector....

ISO 9000 is a family of standards for quality management. It is maintained by the International Organization for Standardization and is administered by the accreditation and certification bodies. ISO 9000 addresses quality management standards as to what an organization needs to fulfill. It assesses the organizations ability to meet customer and regulatory requirements, quality management system, and provides guidelines for performance improvement. It is one of the renowned international standards that have been implemented by countless companies in more than 150 countries.

 

ISO standards aim at:

A set of procedures to cover all key processes in the business.
Monitor the process and ensure its effectiveness.
Quality requirements of customers.
Checking outputs for defects, and taking corrective actions in appropriate places.
Applicable regulatory requirements to enhance customer satisfaction.
Achieve continuous improvement of performance.
 

ISO 9000:2000 and ISO 9001:2000:

 

Earlier till December 2000, there used to be ISO 9000, ISO 9001, ISO 9002 and ISO 9003 standards. During December 2000, the International Organization for Standardization merged all of them into a revised ISO 9001 standard. To distinguish between the earlier standards and the revised one, the later was referred to as ISO 9001:2000 or ISO 9000:2000. For all practical purposes, ISO 9000 and ISO 9001 connote the same, and 2000 indicates the year of its revision.

 

Application in the Textile and Apparel Industries:

 

Textile and apparel industries have many complicated activities and challenges involved in the course of its operation. Their operation incurs heavy expenditure to the manufacturers. Many textile and apparel industries have implemented ISO standards to lower its operating costs and improve the quality of its output, ultimately increasing the level of customer satisfaction. Textile and apparel industries account for a sizable percent of manufacturing jobs in a global perspective. They employ millions of people directly and indirectly. They form a massive industrial complex and prove to be a big contributor among the manufacturing industries of any country.

 

Some textile and apparel industries view ISO certification is only necessary as a factor for exports. But, the main matter of concern in textile industry is that an imperative relation exists between the quality of the materials and the quality of the final product. ISO standards enable the industry to enhance the quality of raw material input, thereby strengthening the quality of the ultimate product. This will result in a systematic approach to management, incessant performance improvement, factual approach towards the decision making process, and a mutually benefiting suppliers relationship. Thus is helps the manufacturers in 'Weaving a Quality Industry'.

 

Market for ISO Certification:
 

As every day passes by, global competition is heating up. Textile and apparel industries are in the midst of major changes. To keep pace with the market scenario, industries rely more on quality and innovative fabrics, and apparels, and quick response to the needs of the customer. Innovations in the fields of nanotextiles, nonwovens, electro textiles, medical textiles, and geo textiles are providing new opportunities for the manufacturers and tap the market. Simultaneously, these opportunities also encompass them with critical challenges. Organizations today engage in many international trade activities, and this certification proves a pre-requisite for their survival in international competition. ISO certification helps the companies in market creation and penetration.

8

Clothtech / Spider silk

« on: November 15, 2018, 04:44:58 PM »

 It is a fibrous protein secreted as a fluid, which hardens as it oozes out of the spinnerets, which are mobile finger-like projections. As the fluid oozes out, the protein molecules are aligned in such a way that they form a solid; the process is not yet well understood. The spider hauls out the silk with its legs, stretching, fluffing it up or changing it in other ways to suit the purpose at hand.

Weight for weight, spider silk is up to 5 times stronger than steel of the same diameter. It is believed that the harder the spider pulls on the silk as it is produced, the stronger the silk gets. Spider silk is so elastic that it doesn't break even if stretched 2-4 times its length. Spider silk is also waterproof, and doesn't break at temperatures as low as -40C.

There are 7 types of silk glands and "nozzles" but no spider has all 7 types

Fig. Two types of silk releasing tubes.
The material is elastic and only breaks at between 2 - 4 times its length. In the pictures a strand of a social spider, stegodyphus sarasinorum, is shown as normal size, stretched 5 times and 20 times its original length. Spider's silk is made up of chains of amino acids. In other words, it is simply a protein .The two primary amino acids are glycine and alanine. Spider silk is extremely strong -- it is about five times stronger than steel and twice as strong as Kevlar of the same weight. Spider silk also has the ability to stretch about 30- percent longer than its original length without breaking, which makes it very resilient

Aramids: -
High tenacity aramide fiber: -
Organic fibers. Closely related to the nylons, aramids are polyamides derived from aromatic acids and amines. Because of the stability of the aromatic rings and the added strength of the amide linkages, due to conjugation with the aromatic structures, aramids exhibit higher tensile strength and thermal resistance than the aliphatic polyamides (nylons). The para- aramids, based on terephthalic acid and p-phenylene diamine, or paminobenzoic acid, exhibit higher strength and thermal resistance than those with the linkages in meta positions on the benzene rings. The greater degree of conjugation and more linear geometry of the para linkages, combined with the greater chain orientation derived from this linearity, are primarily responsible for the increased strength. The high impact resistance of the para-aramids makes them popular for “bullet-proof” body armor. For many less demanding applications, aramids may be blended with other fibers.

9

Meditech / Magic fiber for AIDS diagnosis and treatment

« on: November 15, 2018, 04:43:07 PM »

 
Ashai Chemical Industry Co. have developed a porous hollow fiber membrane BEMBERG MICROPOROUS MEMBRANE [BMM] to filter out and isolate AIDS virus [acquired immune deficiency syndrome virus] and hepatitis type B in blood. BMM is made from cellulose fiber [BEMBERG] regenerated from cuprammonium solutions of cotton linters.

Synthetic polymers are known to cause blood clotting as a result of protein adsorption. However, regenerated cellulose is free from this problem, and for this reason, is used for the artificial kidney in the form of hollow fiber. In order to allow proteins to permeate, but isolate viruses using the same membrane, it is necessary to have homogeneous pores in the membrane, which are larger than proteins but smaller than viruses. To produce such cellulose membranes having homogeneously distributed pores of predetermined diameter. Spherical B-type hepatitis virus and AIDS virus have a diameter of 42 nm and 90-100 nm. Respectively. Thus the membrane needs to have pores of 30-40 nm or 40-75 in diameter, respectively, to isolate these viruses. A single layer of membrane is not sufficient to isolate such viruses completely. Consequently BMM has a multi-layer structure of 100-150 layers. This manufacturing multi layer hollow fiber membrane is produced by wet spinning from cuprammonium solution of cotton linter mixed with an organic solvent. The solution undergoes phase separation and is composed of two phases made up of concentrated and a dilute organic solvent. The concentrated phase forms a continuous organic solvent layer, and the dilute phase make up small organic solvent holes of a uniform size in the cotton linter solution. When spun, the resulting hollow fiber is made of 100-150 layers of cellulose membrane, with pores of a predetermined diameter [see Photo6.2] The pore size and the degree of crystallinity of BMM depends on many external factors such as temperature, solvent composition, component purity and time. Usually BMM is 300 to 400 um in outer diameter, 250 to 350 um in inner diameter, and is composed 40 um in thickness. The actual module is made of 300 BMM hollow fibers which together are 3 cm in diameter and 15 cm in length. Each layer of BMM has over a billion pores, which enables complete filtration and isolation of the viruses.

Uses: -
It is capable of removing virus from plasma and so suppresses its multiplication. AIDS virus immersed into lymphocytes, grows there, and then overflows into plasma. If the isolation rate of virus from plasma is fast, the clinical progress of AIDS can be suppressed. This suppression of the AIDS virus can allow the reactivation of the metabolic functions of the human body, so that treatment efficiency will improve when combined with other medical treatments.

Other applications of BMM are found, for example, in the complete isolation of virus during plasma medicines manufacture, the administration of fractionated plasma-producing medicines for hemophiliacs, and the prevention of virus infection during ordinal plasma transfusion.

BMM is also useful for the isolation of hepatitis non-A non-B virus and in the study of unknown viruses or other physiologically active substances

10

Specialized Wet Processing / Environmental issues in textile

« on: November 15, 2018, 04:36:26 PM »

The international green tribunals are coming up stricter & stricter norms which lead to a higher challenge for a processer and its materials suppliers. ZDHC, GOTS, OEKO TEX, FLO are some of the initiatives taken worldwide which is not only helping to protect environment and health & safety issue but also helping processers for ways & means to achieve green process, saving carbon footprints and reducing / eliminating the  dangerous / banned chemicals in textiles process chain. Air pollution by chimneys, water pollution and earth pollution are the areas which needs attention much more than ever before.

Zero water discharge, recycling of water, recycling of chemicals, modernization of boilers for controlling air pollution and solid waste management are the areas which we need to adopt on this front.

11

Special Fabrics / Development in high performance textile fabrics and materials

« on: November 15, 2018, 04:34:43 PM »

Development in medical textiles-Such innovative textile based implants provide new treatment options in instead of scarce donor organs; artificial tissues, joints and ligaments, which speed up recovery after medical treatment.

Development in textiles for space mission-NASA's space suits are designed to insulate and protect astronauts from a range of temperature extremes from the bone-chilling temperature (-270oCelsius) of deep space to the scorching hot temperature (1,260 oCelsius) of atmospheric re-entry.

Development of high performance fiber-Teijin has developed high performance aramid fibers which are applicable for ballistic protection, cut protection, friction frotection, optical fiber application, rope cable application, heat protection and composites.

Development in smart textiles-With the development of smart textiles, health monitoring of vital signs of the wearer such as heart rate, respiration rate, temperature, activity, and posture becomes easier. It is also helpful in monitoring personnel handling hazardous materials, tracking the position and status of soldiers in action, monitoring pilot or truck driver fatigue.

12

Specialized Wet Processing / Recent development in textile processing

« on: November 15, 2018, 04:33:43 PM »

The world is realizing a very fast change not only in electronic and heavy engineering but also in textile where the textile world not only accepting the challenges being involved for environment & health but also a continuous endeavor to impart comfort and performance which is leading to number of development in textile materials and modernization of processes .

Development in Processing

Plasma Technology - Plasma, very reactive ions, which modify chemical structure and surface properties of textile material. Despite this being costly technology initially, it offers greater production rate, less production cost, better products and most importantly, finishes on fabrics that are either difficult to obtain by other technology or not obtained at all.

Waterless dyeing using supercritical carbon di oxied-In this process dye dissolution to diffusion in to fiber is done with liquid CO It is a completely waterless dyeing process using recycled carbon dioxide in certain temperature and very high pressure. Small scale production has been established but commercialization is still a challenge.

Ultrasonic Assisted Textile Processing- Ultrasound is a cyclic sound pressure which creates vibrational energy in dyes molecules and substrate and increase reaction efficiency and exhaustion. This technique offers less thermal energy requirement, less effluent load, processing through less amount of dyes and auxiliaries and requires smaller size of plant.

Electrochemical dyeing with vat dyes-In this technique the reduction of vat dye molecules is done using electric current. In application of vat dyes, the replacement of non-regenerable reducing agents such as sodium hydro sulphite by cathodically regenerable reducing agents is much better because it offers great ecological advantage.

 Application of ozone in textile industry-Ozone has bleaching property and eliminates tiniting from denim, sewing threads and gives fresh look.  Inspite from its various properties like killing all air borne micro-organisms including bacteria, virus, mold, fungi, spores, etc,  furthermore, the discharge of the Ozone purifies the atmosphere by adding freshness and giving clear, pollution free-oxygen rich air.

Application of nano technology in textiles-Nano finishes has size in the range of 1 to 100 nm, act as catalysts that help break down carbon-based molecules, and require only sunlight to trigger the reaction & being developed for textile substrates are at their infantile stage. However, the new concepts exploited for the development of nano finishes have opened up exciting opportunities for further R&D.

Use of enzyme in textile processing for green technology-Advances in enzymology, molecular biology and screening techniques provide possibilities for the development of new enzyme-based processes for a more environmentally friendly approach in the textile industry. Unfortunately most of enzymes are not certified from various environmental & safety communities only because these are genetically modified otherwise these are non polluting processes.

Fabric from recycled polyester-Polyester textile recycling has been developed using the clear plastic water bottles, or PET as the raw material, a source of plastic that would otherwise go into landfill.

Special finish developments-The consumer safety, resource saving and environment protection contribute to safer textiles and a better future are commitment of Vardhman group, and producing such products in production of special class of finishes, some of which are formaldehyde free resin finished fabric, fluorine free oil & water repellent fabric, cool comfort fabric, anti UV fabric etc.

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Textile Fibres / New recycled polyester developed by Klopman

« on: November 15, 2018, 04:27:19 PM »

KlopmanKlopman has developed a new range of products made with recycled polyester. Europe’s leading brand in work wear has been involved in the production and marketing of blended fabrics in 65 per cent polyester and 35 per cent cotton since 1968.

The basic yarn utilized for the making up of work wear garments can be replaced by similar materials aimed at reducing the environmental footprint, conservation of resources and to support developing countries. Recycled polyester is made from PET plastic bottles, a resource that would otherwise end up in landfills. The challenge for the company was to develop a sustainable product capable of maintaining the features and fabric standards in terms of comfort and durability.

The company also constantly applies its commitment to innovation in accordance with ethical and environmental considerations. From the selection of raw materials through weaving, dyeing and finishing, the company is constantly working to minimize the use of toxic substances, reduce waste, reduce energy consumption and to sustain the development of renewable energies.

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Textile Dyeing / USU biological engineer patents method to make natural blue dye using bacteria

« on: November 15, 2018, 04:24:10 PM »

Utah State UniversityA Utah State University researcher has taken a big step toward making a safer, more natural dye that can be used in the food, textile, cosmetic and other industries. Dr. Jixun Zhan, an associate professor of biological engineering at USU, has secured a patent for an innovative method to produce the deep blue dye known as indigoidine. The tint was originally synthesized from a bacterial strain found in Rhode Island and offered a promising alternative to the synthetic dyes used to color jeans, leather, food, beverages and paper. Zhan’s patent also includes the development of a new method to further process and purify the pigment before it’s ready for use – an important step when using the colorant in food and drinks. Business experts say the patent presents an exciting opportunity across several industries.

“The demand for natural dyes is growing rapidly,” said Christian Iverson, business development director for USU. “I’ve had a number of conversations with food and consumer product companies that are looking for natural dyes to replace some or all the synthetic chemical-based dyes currently in use – in particular blue.”

The invention is just the latest advancement Zhan and his team have made in the growing field of combinatorial biosynthesis. In other studies, Zhan is using bacteria as a heterologous host to produce natural, health-promoting compounds that are normally found in plants. In fact, it was his work on bioactive natural products that led Zhan to the indigoidine bacterium. Zhan says he’s confident manufacturers will see the added value of his natural dye process. He says today’s consumers are increasingly aware of the synthetic ingredients found in everyday products and are looking for natural substitutes wherever possible.

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Specialized Wet Processing / Korean team develops superbug resistant fabric from bacterial pigment

« on: November 15, 2018, 04:17:41 PM »

UNISTAn industry-academia team in South Korea has effectively used pigment from bacteria found in nature to develop superbug resistant fabrics. A team of institute-industry partners affiliated with Ulsan National Institute of Science and Technology (UNIST) involving Korean Institute of Ceramic Engineering and Technology, industrial partner, Yeejoo Company and UNIST has used bacterial pigment “Violacein,” to impart antimicrobial properties.

Violacein, an indole derivative is a violet pigment made by naturally occurring bacteria such as those belonging to genus such as Chromobacterium. Violacein has been reported to have antimicrobial and antiparasital properties in microbiology related literature.

The bacterial pigment was coated to the fabric and has been reported to have good efficacy to MRSA and multi drug resistant Staphylococcus aureus. The coated fabrics inhibited the growth of MRSA and other supebugs by 99.9 percentage, according to UNIST. The work could be first of its kind to effectively utilize bacterial pigment as a coating agent on fabrics to impart antimicrobial properties. The Korean team has developed prototype face masks and they are currently being put to use in a local hospital in Ulsan city, South Korea. UNIST is a young national University in South Korea with emphasis on science and technology established in the year, 2007 in Ulsan city.