Polymer system:
The polyester is linear is linear
and is usually based on polyethylene terephthalate. The degree of polymerization
range from about 115 to 140 resulting in
a polymer length of about 120 mm to 150 nm with a thickness of about of
0.6 nm.
The important chemical group in
the polyester is the methylene groups (-CH2-) the slightly polar carbonyl groups (-Co) -,and the ester groups (-OCO-)
.
 |
| dry polymer system |
.
Physical properties:
1. Tenacity:
Polyester filaments and staple fibers
are strong to very strong because of their extremely crystalline polymer
system.
High tenacity filament 7-8 gm/den
Normal
tenacity filaments 4.5-5.0”
2. Hygroscopic:
Polymer filaments and staple fibers
are hydrophobic. The lack of polarity and
the extremely crystalline structure of polyester resist the entry of water
molecules into the polymer system. MR%
_0-0.4%
Chemical properties:
1. Effect
of acid:
The ester groups of the polyester polymers are
resistant to acid hydrolysis. This resistance is further enhanced by the
extreme crystallinity of the polyester polymer system.
2. Effect
of alkali: Sensitive to alkali.
3. Effect
of bleaches:
Normally polyester textile mlts
do not need to be bleached. If bleached is required this is achievely by using
hypo chloride bleaching.
4. Dry
ability:
It is very difficult for dye molecules
to penetrate the extremely crystalline polymer system of polyester fiber.
5. Biological
agents: Resistance for months, mildews, fungus.
6. Flammability:
burn slowly.
End use of polyester:
- Apparel use: men /women, children wear, tropical setting , blending with cotton, wool, acrylic, nylon etc.
- Domestic use: floor covering, carpet etc.
- Industrical use:High tenacity PET for tire coards, v-ropes, sail cloth, conveyor belts, paper making.
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