How to buy a quality sofa – part 4: synthetic fibers

3 10 2012

So from last week’s post, you  know that you want a durable, colorfast fabric that will be lovely to look at and wonderful to live with.  What’s the best choice?  I’m so glad you asked.

You have basically two choices in fibers:  natural (cotton, linen, wool, hemp, silk)  or synthetic (polyester, acrylic, nylon, etc.).  Many fabrics today are made from blends of natural and synthetic fibers – it has been said that most sheet sets sold in the U.S. are cotton/poly blends.

Natural fibres breathe, wicking moisture from the skin, providing even warmth and body temperature;  they are renewable, and decay at end of life.  On the other hand, synthetics do not breathe,  trapping body heat and perspiration; they are based on crude oil, definitely a non-renewable resource and they do not decompose at end of life, but rather remain in our landfills, leaching their toxic monomers into our groundwater.  They are, however, cheap and durable.

I like to think that even without the health issues involved I’d choose to live with natural fibers, since they work so well with humans!  The fibers themselves present no health issues and they’re comfortable.  But they simply don’t last as long as synthetics. But I have begun to see the durability of synthetics as their Dorian Grey aspect, in other words they last so long that they’ve become a huge problem.  By not decomposing, they just break into smaller and smaller particles which leach their toxic monomers into our groundwater.

The impact on health (ours the the planet’s) is an issue that’s often overlooked when discussing the merits of natural vs. synthetic.   And it’s a complex issue, so this week we’ll explore synthetic fibers, and next week we’ll look at natural fibers.

The most popular synthetic fiber in use today is polyester.

At this point, I think it would be good to have a basic primer on polyester production, and I’ve unabashedly lifted a great discussion from Marc Pehkonen and Lori Taylor, writing in their website diaperpin.com:

Basic polymer chemistry isn’t too complicated, but for most people the manufacture of the plastics that surround us is a mystery, which no doubt suits the chemical producers very well. A working knowledge of the principles involved here will make us more informed users.

Polyester is only one compound in a class of petroleum-derived substances known as polymers. Thus, polyester (in common with most polymers) begins its life in our time as crude oil. Crude oil is a cocktail of components that can be separated by industrial distillation. Gasoline is one of these components, and the precursors of polymers such as polyethylene are also present.

Polymers are made by chemically reacting a lot of little molecules together to make one long molecule, like a string of beads. The little molecules are called monomers and the long molecules are called polymers.

Like this:

O + O + O + . . . makes OOOOOOOOOOOOOOOO

Depending on which polymer is required, different monomers are chosen. Ethylene, the monomer for polyethylene, is obtained directly from the distillation of crude oil; other monomers have to be synthesized from more complex petroleum derivatives, and the path to these monomers can be several steps long. The path for polyester, which is made by reacting ethylene glycol and terephthalic acid, is shown below. Key properties of the intermediate materials are also shown.

The polymers themselves are theoretically quite unreactive and therefore not particularly harmful, but this is most certainly not true of the monomers. Chemical companies usually make a big deal of how stable and unreactive the polymers are, but that’s not what we should be interested in. We need to ask, what about the monomers? How unreactive are they?

We need to ask these questions because a small proportion of the monomer will never be converted into polymer. It just gets trapped in between the polymer chains, like peas in spaghetti. Over time this unreacted monomer can escape, either by off-gassing into the atmosphere if the initial monomers were volatile, or by dissolving into water if the monomers were soluble. Because these monomers are so toxic, it takes very small quantities to be harmful to humans, so it is important to know about the monomers before you put the polymers next to your skin or in your home. Since your skin is usually moist, any water-borne monomers will find an easy route into your body.

Polyester is the terminal product in a chain of very reactive and toxic precursors. Most are carcinogens; all are poisonous. And even if none of these chemicals remain entrapped in the final polyester structure (which they most likely do), the manufacturing process requires workers and our environment to be exposed to some or all of the chemicals shown in the flowchart above. There is no doubt that the manufacture of polyester is an environmental and public health burden that we would be better off without.

What does all of that mean in terms of our health?  Just by looking at one type of cancer, we can see how our lives are being changed by plastic use:

  • The connection between plastic and breast cancer was first discovered in 1987 at Tufts Medical School in Boston by research scientists Dr. Ana Soto and Dr. Carlos Sonnenschein. In the midst of their experiments on cancer cell growth, endocrine-disrupting chemicals leached from plastic test tubes into the researcher’s laboratory experiment, causing a rampant proliferation of breast cancer cells. Their findings were published in Environmental Health Perspectives (1991)[1].
  • Spanish researchers, Fatima and Nicolas Olea, tested metal food cans that were lined with plastic. The cans were also found to be leaching hormone disrupting chemicals in 50% of the cans tested. The levels of contamination were twenty-seven times more than the amount a Stanford team reported was enough to make breast cancer cells proliferate. Reportedly, 85% of the food cans in the United States are lined with plastic. The Oleas reported their findings in Environmental Health Perspectives (1995).[2]
  • Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic. [3]

These studies support claims that plastics are simply not good for us – prior to 1940, breast cancer was relatively rare; today it affects 1 in 11 women.  We’re not saying that plastics alone are responsible for this increase, but to think that they don’t contribute to it is, we think, willful denial.  After all, gravity existed before Newton’s father planted the apple tree and the world was just as round before Columbus was born.

Polyester fabric is soft, smooth, supple – yet still a plastic.  It contributes to our body burden in ways that we are just beginning to understand.  And because polyester is highly flammable, it is often treated with a flame retardant, increasing the toxic load.  So if you think that you’ve lived this long being exposed to these chemicals and haven’t had a problem, remember that the human body can only withstand so much toxic load – and that the endocrine disrupting chemicals which don’t seem to bother you may be affecting generations to come.

And then there is acrylic.  The key ingredient of acrylic fiber is acrylonitrile, (also called vinyl cyanide). It is a carcinogen (brain, lung and bowel cancers) and a mutagen, targeting the central nervous system.  According to the Centers for Disease Control and Prevention, acrylonitrile enters our bodies through skin absorption, as well as inhalation and ingestion.  So could the acrylic fibers in our acrylic fabrics be a contributing factor to these results?

Acrylic fibers are just not terrific to live with anyway.  Acrylic manufacturing involves highly toxic substances which require careful storage, handling, and disposal. The polymerization process can result in an explosion if not monitored properly. It also produces toxic fumes. Recent legislation requires that the polymerization process be carried out in a closed environment and that the fumes be cleaned, captured, or otherwise neutralized before discharge to the atmosphere.(4)

Acrylic is not easily recycled nor is it readily biodegradable. Some acrylic plastics are highly flammable and must be protected from sources of combustion.

Just in case you missed the recent report which was published in Occupational and Environmental Medicine [5], a Canadian study found that women who work with some common synthetic materials could treble their risk of developing breast cancer after menopause. The data included women working in textile factories which produce acrylic fabrics – those women have seven times the risk of developing breast cancer than the normal population, while those working with nylon fibers had double the risk.

What about nylon?  Well, in a nutshell, the production of nylon includes the precursors benzene (a known human carcinogen) and hydrogen cyanide gas (extremely poisonous); the manufacturing process releases VOCs, nitrogen oxides and ammonia.  And finally there is the addition of those organophosphate flame retardants and dyes.

[1] http://www.bu-eh.org/uploads/Main/Soto%20EDs%20as%20Carcinogens.pdf

[2] http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.95103608

[3] Sax, Leonard, “Polyethylene Terephthalate may Yield Endocrine Disruptors”,
Environmental Health Perspectives, April 2010, 118 (4): 445-448

(4) ) http://www.madehow.com/Volume-2/Acrylic-Plastic.html

(5) Occupational and Environmental Medicine 2010, 67:263-269 doi: 10.1136/oem.2009.049817 (abstract: http://oem.bmj.com/content/67/4/263.abstract) SEE ALSO: http://www.breastcancer.org/risk/new_research/20100401b.jsp AND http://www.medpagetoday.com/Oncology/BreastCancer/19321

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Outdoor fabrics

25 03 2012

We love being outdoors. I’ve been told that the most popular outdoor activity in the U.S.A is picnicking.  I would think barbeque must be a close second.  So we love fabrics that we can use outdoors  – you know the ones that resist fading, are stain resistant and can be cleaned with mild soap and water?  They don’t fade or degrade.  Perfect!

Let’s look at America’s most popular outdoor fabric, Sunbrella, which their website claims is recognized as “a fabric with a conscience”, because, as they claim:

  • all Sunbrella fabrics are fully recyclable;
  • they require no dyeing that produces wastewater;
  • and they have received the GREENGUARD and Skin Cancer Foundation certifications.

Before we show why we think these are all claims which exemplify different facets of what Terra Choice calls the “Six Sins of Greenwashing”, let’s first look at the stuff Sunbrella is made of.

Sunbrella is, as their website says, a 100% solution dyed acrylic fabric.   Solution dyeing is simply mixing the dyestuff into the melted polymer.  So unlike dyeing that penetrates a fiber,  this method means that the color is inherent in the fiber, and there is no dye or water waste.  This is a good method of dyeing – but that’s not the issue  – the real issue is what the fabrics are made of.

The key ingredient of acrylic fiber is acrylonitrile, (also called vinyl cyanide).   Acrylic manufacturing involves highly toxic substances which require careful storage, handling, and disposal. The polymerization process can result in an explosion if not monitored properly.  It also produces toxic fumes. Recent legislation requires that the polymerization process be carried out in a closed environment and that the fumes be cleaned, captured, or otherwise neutralized before discharge to the atmosphere – because the burning of acrylic releases fumes of hydrogen cyanide and oxides of nitrogen.

The International Agency for Research on Cancer (IARC) concluded that there is inadequate evidence in humans for the carcinogenicity of acrylonitrile, but classified it as a Class 2B carcinogen (possibly carcinogenic).   Acrylonitrile increases cancer in high dose tests in male and female rats and mice. (1)    A recent report which was published in Occupational and Environmental Medicine  found that women who work in textile factories which produce acrylic fabrics have seven times the risk of developing breast cancer than the normal population.(2)

According to the Centers for Disease Control and Prevention, acrylonitrile enters our bodies through skin absorption, as well as inhalation and ingestion.

Acrylic is not easily recycled nor is it readily biodegradable. It is considered a group 7 plastic among recycled plastics and is not collected for recycling in most communities. Large pieces can be reformed into other useful objects if they have not suffered too much stress, crazing, or cracking, but this accounts for only a very small portion of the acrylic plastic waste. In a landfill, acrylic plastics, like many other plastics, are not readily biodegradable. Some acrylic plastics are highly flammable and must be protected from sources of combustion.

Now that you know what Sunbrella’s made of, let’s look at their claims:

  • All Sunbrella fabrics are fully recyclable – If you check the website, Sunbrella has a proprietary recycling program, which means they will pick up your old Sunbrella.  Why do they do this?  Because the local municipalities do not accept acrylic fabric nor do most plastic recycling companies.  It’s admirable that Sunbrella has put this program into place, but we don’t really know that they actually re-purpose the old fabric rather than simply cart it to the landfill, do we?
  • Sunbrella fabrics require no dyeing that produces wastewater  – because it’s solution dyed, so therefore this is, well if not exactly a red herring, certainly irrelevant to the fact that the fabric is made from acrylic.
  • Sunbrella fabrics have received the GREENGUARD and Skin Cancer Foundation certifications.
    • Sunbrella fabrics have been certified by GreenGuard Children and Schools because the chemicals used in acrylic production are bound in the polymer – in other words, they do not evaporate. So Sunbrella fabrics do not contribute to poor air quality, (you won’t be breathing them in), but there is no guarantee that you won’t absorb them through your skin. And you would be supporting the production of more acrylic, the production of which is not a pretty thing.
    • With regard to the Skin Cancer Foundation – the certification seems to be based on the fact that Sunbrella fabrics block the sun, which prevents skin cancer, rather than anything inherently beneficial in the fabric itself – because the certification is not valid for any Sunbrella fabric which is sheer or transparent.  So another red herring.

Now that you know what Sunbrella is made of, do you really want convenience at such a great cost?


(1) Hagman, L, “How confident can we be that acrylonitrile is not a human carcinogen?”, Scandanavian Journal of Work, Environment and Health, 2001;27(1):1-4 .

[2] Occupational and Environmental Medicine 2010, 67:263-269 doi: 10.1136/oem.2009.049817 (abstract: http://oem.bmj.com/content/67/4/263.abstract) SEE ALSO: http://www.breastcancer.org/risk/new_research/20100401b.jsp AND http://www.medpagetoday.com/Oncology/BreastCancer/19321





Breast cancer and acrylic fibers

16 09 2010

Just in case you missed the recent report which was published in Occupational and Environmental Medicine [1], a Canadian study found that women who work with some common synthetic materials could treble their risk of developing breast cancer after menopause.  The data included  women working in textile factories which produce acrylic fabrics   –  those women have seven times the risk of developing breast cancer than the normal population, while those working with nylon fibers had double the risk.

I found it interesting that the researchers justified their findings because “synthetic fibers are typically treated with several chemicals, such as flame retardants from the organophosphate family, delustering agents, and dyes, some of which have estrogenic properties and may be carcinogenic.”

These are the same organophosphate flame retardants and dyes that are used across the textile spectrum, and which are found in most textiles that we surround ourselves with each day.

But also let’s look at the fibers themselves.  The key ingredient of acrylic fiber is acrylonitrile, (also called vinyl cyanide). It is a carcinogen (brain, lung and bowel cancers) and a mutagen, targeting the central nervous system.  According to the Centers for Disease Control and Prevention, acrylonitrile enters our bodies through skin absorption, as well as inhalation and ingestion.  So could the acrylic fibers in our acrylic fabrics be a contributing factor to these results?

Acrylic fibers are just not terrific to live with anyway.  Acrylic manufacturing involves highly toxic substances which require careful storage, handling, and disposal. The polymerization process can result in an explosion if not monitored properly. It also produces toxic fumes. Recent legislation requires that the polymerization process be carried out in a closed environment and that the fumes be cleaned, captured, or otherwise neutralized before discharge to the atmosphere.(2)

Acrylic is not easily recycled nor is it readily biodegradable. Some acrylic plastics are highly flammable and must be protected from sources of combustion.

What about nylon?  Well, in a nutshell, the production of nylon includes the precursors benzene (a known human carcinogen) and hydrogen cyanide gas (extremely poisonous); the manufacturing process releases VOCs, nitrogen oxides and ammonia.  And finally there is the addition of those organophosphate flame retardants and dyes.

Of course, there are the usual caveats about the study, and those commenting on it said further studies were needed since chance or undetected bias could have played a role in the findings. In addition, according to Reuters, “the scientists said more detailed studies focusing on certain chemicals were now needed to try to establish what role chemical exposure plays in the development of breast cancer.”  So this is yet another area in which more research needs to be done.  No surprise there.

But in the meantime, did you know that many popular fabrics are made of acrylic fibers?   One of the most popular is Sunbrella outdoor fabrics.     Sunbrella fabrics have been certified by GreenGuard Children and Schools because the chemicals used in acrylic production are bound in the polymer – in other words, they do not evaporate.   So Sunbrella fabrics do not contribute to poor air quality, (you won’t be breathing them in), but there is no guarantee that you won’t absorb them through your skin.  And you would be supporting the production of more acrylic, the production of which is not a pretty thing.

And what about backings on fabrics?  Many are made of acrylic.  Turn those fabric samples over and see if there is a plastic film on the back – it’s often made of acrylic.  Upholsterers like fabrics to be backed because it makes the process much easier and stabilizes the fibers.

So I don’t know about you, but I think I’ll avoid those synthetics for now – at least until we know where we stand.


[1] Occupational and Environmental Medicine 2010, 67:263-269 doi: 10.1136/oem.2009.049817  (abstract: http://oem.bmj.com/content/67/4/263.abstract)  SEE ALSO:  http://www.breastcancer.org/risk/new_research/20100401b.jsp AND http://www.medpagetoday.com/Oncology/BreastCancer/19321

(2)  http://www.madehow.com/Volume-2/Acrylic-Plastic.html





Man-made synthetic fibers

7 07 2010

For millennia mankind depended on the natural world to supply its fiber needs.  But scientists, as a result of extensive research, were able to replicate naturally occurring animal and plant fibers by creating fibers from synthetic chemicals. In the literature, it is often noted that there are three kinds of man-made fibers: those made by “transformation of natural polymers” (also called regenerated cellulosics), those made from synthetic polymers and those made from inorganic materials (These include the fibers made of glass, metal, ceramics and carbon.) But by far the largest group of man made synthetic fibers being produced today are made from synthetic polymers, so we’ll concentrate on those in this post.

Man made  fibers from synthetic polymers  are created using polymerization of various chemical inputs to create polymers.  Polymerization is the process of combining many small molecules into a large molecule – a polymer.    Polymers are simply large molecules composed of repeating structural units.  Polymers used for synthetic fibers are produced from intermediates (which in turn have been produced from crude oil) and applying a catalyst.  Key intermediates are p-Xylene, teraphtalic acid, ethylene glycol and acrylonitrile;  catalysts – manganese, cobalt and antimony oxide –  are used to control the processes.

Polymers are the building blocks of synthetic fibers – and of many other things.   They are the basis of life and play an essential and ubiquitous role in our everyday life, ranging from familiar synthetic plastics to natural biopolymers such as DNA and proteins that are essential for life.  Natural polymeric materials such as shellac, amber and natural rubber have been in use for centuries. Biopolymers, such as proteins and nucleic acids, play crucial roles in biological processes. A variety of other natural polymers exist, such as cellulose, which is the main constituent of cotton and wood.

Synthetic polymers include vulcanized rubber, Bakelite and neoprene (and many more) in addition to polymers used in fibers:   polyester, nylon, polystyrene, polyethylene, PVC, and polyacrylonitrile (known as acrylic).

Synthetic fibers account for about half of all fiber usage, with applications in every field of fiber and textile technology.  Four synthetic fibers – nylon, polyester, acrylic and polyolefin – dominate the market. These four account for approximately 98% by volume of global synthetic fiber production.  But make no mistake, polyester is king:   polyester alone accounted for around 80% of the global market share of man made fibers.[1] Polyester has become the fiber of choice (sometimes blended with cotton) in garment production.  As recently as 1990, world polyester production totaled 20 billion pounds.  In 2002, production had more than doubled to 46 billion pounds – and was 61.5 billion pounds in 2009. [2] Polyester fiber consumption increased at an annual growth rate of 6.2% between 1998 and 2008,[3] although demand has recently moderated as a result of the global economic slowdown.

The raw materials used in synthetic production are mainly produced by large chemical companies which are sometimes integrated down to the crude oil refinery where p-Xylene is the base material used to produce other intermediaries.  For example p-Xylene is used to produce teraphtalic acid.   Major producers of teraphtalic acid include:

  • BP
  • Reliance (India-based Reliance just bought Trevira GmbH&Co)
  • Eastman Chemicals
  • Mitsui
  • Sinopec
  • SK-Chemicals

Among the world’s largest polyester producers are the following companies:

  • DuPont
  • Eastman
  • Invista
  • Wellman
  • M&G Group
  • Mitsui
  • Mitsubishi
  • Reliance
  • Teijin
  • Toray
  • Hyosung
  • Huvis
  • Jiangsu Hengli Chemical Fiber
  • Jiangsu Sanfangxian Industry
  • NanYa Plastics

Synthetic fiber production has definitely moved to Asian countries.   As stated in Textile World :   “the critical mass of fiber manufacturing from the industrialized West to the developing East is a study in comparative economics and social realities.”  In 1990, China represented barely 8% of total man-made production; by 2002 it produced almost 30% (almost a tie with the US and Europe).   India is also making a pitch to be a player: From a virtually nonexistent position in 1990 to currently 5%, with programs in place to expand this further.   According to Textile World, the world of polyester production has begun to resemble a monopoly, led by China.  “The speed with which Asia has dominated fiber production is astounding. The commitment is complete, and the world man-made fiber industry will never be the same – and that’s not necessarily a bad thing. It is obvious that production asset investments of the recent decade are world-class in efficiency and quality – with the world consumer receiving the benefits. The industrialized world must move on to a higher-return economy and let the developing world be satisfied by lower returns on investment, either through lower labor or local funds costs; or government-subsidized manufacturing aimed at employment, and/or accumulation of strong currencies to be used for continued economic development. Either way, the new nexus of the man-made fiber business is Asia.”

Since polyester is the king of synthetics (and because the data is available!) let’s look at how polyester is formed.

 

POLYMERIZATION:
First, the polymer is created; in the case of polyester, the polymer is made by heating either dimethyl teraphthalate (DMT)  or terephthalic acid (TPA) with ethylene glycol in the presence of a catalyst (ususally antimony) at 536 º F for 30 minutes at atmospheric pressure and then for 10 hours under vacuum. The excess of ethylene glycol is distilled off.  The resulting chemical, a monomer (single, non-repeating molecule) alcohol, is combined with terephthalic acid and raised to a temperature of 472°F (280°C). Newly-formed polyester, which is clear and molten, is extruded through a slot to form long ribbons.

DRYING: After the polyester emerges from polymerization, the long molten ribbons are allowed to cool until they become brittle. The material is cut into tiny chips and completely dried to prevent irregularities in consistency.

SPINNING:  Fibers are classified according to the type of spinning that the polymer undergoes: this can be melt spinning, dry spinning or wet spinning:

  1. Melt spinning is the simplest of these three methods:   In melt spinning, the polymer chips are melted at 500 – 518ºF to form a syrup-like solution.  The solution is put in a metal container called a spinneret and forced through its tiny holes. The number of holes in the spinneret determines the size of the yarn, as the emerging fibers are brought together to form a single strand. Melt spinning is used with polymers such as nylon, polyethylene, polyvinyl chloride, cellulose triacetate, and polyethylene terephthalate, and in the multifilament extrusion of polypropylene.
  2. Dry spinning:  the polymer is first dissolved in a solvent. The polymer solution  is then extruded through the spinnerets. The solvent is evaporated with hot air and collected for reuse. The fiber then passes over rollers, and is stretched to orient the molecules and increase the fiber strength. Cellulose acetate, cellulose triacetate, acrylic, modacrylic, aromatic nylon, and polyvinyl chloride are made by dry spinning.
  3. In wet spinning, the polymer solution (i.e., polymer dissolved in a solvent as in dry spinning) is spun into a coagulating solution to precipitate the polymer. This process has been used with acrylic, modacrylic, aromatic nylon, and polyvinyl chloride fibers.

For each pound of fiber produced with solvent spinning processes (dry or wet), a pound of polymer is dissolved in about 3 pounds of solvent.  So the capture and recovery of these solvents is an integral part of the solvent spinning process.  At present, most solvents are recovered, however emissions from the spinning operation are a significant consideration.  But air pollution emissions from polyester fiber production also include polymer dust from drying operations, volatilized residual monomer, fiber lubricants (in the form of fume or oil smoke) and the burned polymer and combustion products from cleaning the spinning equipment.

At the spinning stage, other chemicals may be added to the solution to achieve various effects such as making the material flame retardant, antistatic, or colorful (by adding dye chemicals).  Because these fibers are created from crude oil, they’re highly flammable (in fact, they’re considered an accelerant)  and pose a great threat for fire injury.  The development of a durable flame retardant for synthetics was key in the safe consumer use of synthetic fibers.

It is at the spinning stage that the two varieties of polyester fibers are created: filament and staple fibers:

  • FILAMENT:  When polyester emerges from the spinneret, it is soft and easily elongated up to five times its original length.  To create filament, the fibers are stretched.  The stretching forces the random polyester molecules to align in a parallel formation. This increases the strength, tenacity, and resilience of the fiber. This time, when the filaments dry, the fibers become solid and strong instead of brittle.   Stretched, or drawn,  fibers may vary greatly in diameter and length, depending on the characteristics desired of the finished material. Also, as the fibers are drawn, they may be textured or twisted to create softer or duller fabrics. After the polyester yarn is drawn, it is wound on large bobbins or flat-wound packages, ready to be woven into material.
  • STAPLE:  To create staple fiber, the spinneret has many more holes than when the production is filament fiber.  The rope like bundles of polyester that emerge are called tow.
    • Newly-formed tow is quickly cooled in cans that gather the thick fibers. Several lengths of tow are gathered and then drawn on heated rollers to three or four times their original length.
    • CRIMPING: Drawn tow is then fed into compression boxes, which force the fibers to fold like an accordion, at a rate of 9-15 crimps per inch (3-6 per cm). This process helps the fiber hold together during the later manufacturing stages.
    • SETTING: After the tow is crimped, it is heated at 212-302°F (100-150°C) to completely dry the fibers and set the crimp. Some of the crimp will unavoidably be pulled out of the fibers during the following processes.
    • CUTTING:  Following heat setting, tow is cut into shorter lengths. Polyester that will be blended with cotton is cut in 1.25-1.50 inch (3.2-3.8 cm) pieces; for rayon blends, 2 inch (5 cm) lengths are cut. For heavier fabrics, such as carpet, polyester filaments are cut into 6 inch (15 cm) lengths.

By and large, synthetic fibers are used for their utility in specific markets.

Polyester is difficult and expensive to dye, but has attributes that make it ideal for blending with cotton and other natural fibers.  Easy care of the permanent press fabric made polyester doubleknits extremely popular in the late 1960s.


However, polyester has suffered an “image problem” since that time, and clothes made out of polyester were often devalued and even ridiculed.  Polyester has the advantage of being very cheap to produce, but it is a much less attractive fiber to live with when compared to the inherent breathability, moisture absorption capabilities and heat moderation inherent in natural fibers.  Polyesters have the advantage in wash-and-wear properties, wrinkle resistance – and in durability.   Manufacturers tried to make polyester easier to use in garments by blending polyester with cotton, wool or other natural fibers.   Several new forms of polyester introduced in the early 1990s may help revitalize the image of polyester. A new form of polyester fiber, called microfiber, was introduced to the public in 1991.  Microfibers have diameters that are less than typical fibers; they are about half the diameter of fine silk fiber, one-quarter the diameter of fine wool, and one hundred times finer than human hair. Microfibers allow a fabric to be woven that is lightweight and strong. They can be tightly woven so that wind, rain, and cold do not easily penetrate. Rainwear manufactures use microfibers for this reason. They also have the ability to allow perspiration to pass through them. In addition, microfibers are very flexible because their small fibers can easily slide back and forth on one another. The first fabric made from microfiber was Ultrasuade, in which short polyester microfibers were imbedded into a polyurethane base. Today, microfibers are manufactured primarily from polyesters, nylon, and acrylic fibers. They are used under various trade names to make a variety of products, such as clothing, hosiery, bedding, and scarves.

Textile researchers at North Carolina State University are developing a form of polyester that may be as strong as Kevlar, a superfiber material used to make bulletproof vests.

Nylon, the granddaddy of man-made fibers, seems to be losing share to polyester, overwhelmed by sheer volume if not performance. In carpets, staple nylon gradually is being replaced by filament; tires increasingly use polyester over nylon; and many woven industrial and apparel fabrics seem to favor polyester. Nylon’s dyeability is an advantage, but not sufficiently so to overcome the supply and variants available in polyester.

Acrylic gradually is losing the price battle with polyester and increasingly is relegated to bulk and wool-substitute end-uses.


[1]http://www.officialwire.com/main.php?action=posted_news&rid=137418

[2] Luke, John; Fiber World: A Polyester Saga Geography and All; Textile World; http://www.textileworld.com/Articles/2004/September/Fiber_World/A_Polyester_Saga_Geography_And_All.html

[3] http://www.officialwire.com/main.php?action=posted_news&rid=137418