REFERENCES of polyster articles

Handbook of
Fiber
Chemistry
Third Edition
Edited by
Menachem Lewin

WORLD MARKETS AND FUTURE PROSPECTS FOR POLYESTER FIBERS

The total world market for all synthetic fibers in 2002 was around 36,000,000 tons. Of this
total, 21,500,000 tons is PET and the rate of consumption is still growing, although
apparently slowing. Over the past 15 years, there have been cataclysmic changes in the
polyester-producing fiber business. The gradual eclipse of the textile industry in the United
States and much of western Europe and its geographical shift to Asia and other places, such
as Central America and parts of Eastern Europe, has brought about these changes. Old,
firms like ICI, Hoechst, Monsanto, and Eastman have disappeared completely from
the fiber-producing scene. The last survivor was DuPont which announced in February
2002 that they would split off all their fiber and textile interests as a separate industry
under the name Invista. In November 2003, Koch Industries announced that they would
acquire Invista.
The new generation of polyester fiber producers buy polymer in the open market as a
commodity item and convert it into fiber and yarn. They have revolutionized the market and
superseded the old order. Koch Industries buy PPT polymer from Shell and spin Corterra
fibers and market them, although Shell retains the trademark and Koch proposes to build its
own polymer plant in Mexico. The emergence of China as a major consumer and producer of
polyester fiber (it outstripped the United States in polyester production in 1998) will have a
major effect on world markets.
The market for polyester fiber will certainly continue to grow overall, although, as a major
commodity item, it is likely to be affected much more than in the past by global economics and
trade cycles. Certainly, the price of raw materials like crude oil and natural gas will have an
effect on process costs and markets. Nevertheless, there is still a trend to replace other fibers,
both natural and synthetic, with polyester. Nylon is still losing markets to polyester. At present,
nylon dominates polyester in domestic carpet yarns, but because PET is cheaper, it has a
growing share of the contract carpet trade. The new microfibers and newer easy-to-dye
polyesters with excellent resilience (like PTT) would be expected to make big inroads into
floor coverings and the apparel markets over the next few years. It was confidently expected
that PTT would have an immediate impact on the carpet business (one place where PET
polyester suffers) in 1999–2000 when Corterra was first launched. So far this has not happened,
but fiber price and availability are major factors as always. In the long term, there are new
nonoil-based biomass-derived processes in commercial production for making not just intermediates
for polyesters but even the polymers themselves. The effect of recycling polyester such
as soda bottles into fiberfill and carpet yarns may also have unpredictable effects.

NOVEL FIBER FORMS

MICROFIBERS
Microfiber is arbitrarily defined as a filament of less than 1.0 dpf. Normal filament yarn
polyester is around 3. 0–5.0 dpf. Microfibers are many times finer than a human hair and finer
than the finest silk: diameters are generally less than 10 mm. A typical polyester microfiber has
a titer of about 0.5 dpf. Such fine fibers in the form of yarns have excellent textile properties.
They are very flexible, giving a soft ‘‘hand’’ and excellent drape to fabrics. The high density of
fibers in a typical microfiber fabric makes it inherently windproof and waterproof. There are
only tiny gaps for air to blow through, yet the fabrics are largely unwettable, because surface
tension effects prevent water from penetrating the interstices in the fabric. These fabrics are
comfortable to wear as water vapor from perspiration evaporates easily. Their fabric properties
make them ideal for women’s wear, sportswear, active, and outdoor wear. They have
(radiant) heat-insulating properties because the filaments are of the same dimensional order
as the wavelengths of infrared radiation. A 0.5 dpf polyester filament (density1.4 g=cm3)
has a diameter of about 7 mm, right in the middle of the IR wavelength range (2–20 mm).
Hence, radiation is efficiently scattered by the microfibers and radiation loss of body heat is
reduced.

BICOMPONENT FIBERS AND MICROFIBERS

Bicomponent fibers or ‘‘heterofil’’ fibers are filaments made up of different polymers. There
are many geometrical arrangements. The three main heterofil geometries are side-by-side,
core–sheath (both concentric and eccentric), and the multiple core or ‘‘islands in a sea’’
configuration. The so-called ‘‘splittable pie’’ configurations are used in the production of
microfibers (see Figure 1.12).
The two polymer components do not have to differ in ‘‘chemical’’ nature. They can
differ only in physical parameters such as molecular weight. Usually, it is desirable that the
two components have good mutual adhesion, but not always. Polyolefines do not bond well
with polyesters or polyamides and this fact is exploited in the formation of microfibers (see
later).

DYEING POLYESTERS

INTRODUCTION
Dyeing synthetic fibers is a huge subject in its own right and the reader is advised to consult
one of the many publications that deal with it comprehensively [61]. When PET fibers first
appeared, they presented many problems for traditional dyers. PET has no functional groups
to give affinity for usual dyestuffs. Natural fibers like wool, cotton, silk, and then later manmade
ones like rayon and nylon were well known and had good dye affinities because the
fibers had pendant or terminal functional chemical groups such as –NH2, –COOH, and –OH.
These dyes were developed to interact with such groups. The only way to dye polyester was to
rely on Van der Waals forces to hold the dye in the fiber. All classic cationic and anionic dyes
for wool and silk or direct dyes for cotton had water-solubilizing ionic groups like

NR₃⁺and

SO₃^-

. Such dyes had little or no affinity for PET.