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POLYESTER

F.T.C. Definition: A manufactured fiber in which the fiber forming substance is any long chain synthetic polymer composed of at least 85% by weight of an ester of dihydric alcohol such as ethylene glycol and terephthalic acid. An alternative method of producing polyester is reacting dimethyl terephthalic with ethylene glycol.

Polyester is manufactured by the direct esterification of terephthalic acid with ethylene glycol in a vacuum under extreme heat. The polymere is then dried and chipped into pellets. The pellets are in turn melted into the spinning solution. Next, the spinning solution is pumped through a spinneret to form the polyester fiber. The fibers are stretched several times their original length, which orients the long chain molecules and gives the fiber strength. The polyester is then wound onto packages for shipment. To manufacture Spun Polyester, the fiber is cut into staple length and crimped. The staple fiber is then spun in much the same way as cotton.

PHYSICAL CHARACTERISTICS OF POLYESTER

WATER: Not significantly affected by immersion in water. Loses about 2 to 3% tenacity, but regains fully when dry. Boiling water causes shrinkage and permanent loss of strength. Standard moisture regain 0.5%.
HEAT:    Resistant to dry heat. Affected by prolonged temperatures of 180° C or more. Burns with smoky flame. Melts away from flame.
ACIDS: Resistant, but disintegrates on exposure to heated mineral acids.
ALKALIS: Generally good resistance, hydrolysis occurs slowly at ambient temperatures and rapidly when heated. Amines degrade polyester, expecially cyclo-Hexylamine. Amines in rubber cause severe degradation.
SOLVENTS: Resistant to standard hydrocarbon, aromatic and chlorinated solvents. Soluble in Phenols. Soluble in boiling benzyl alcohol, nitro benzene, dimethyl phthalate and ethylene glycol.
MISC: Not harmed by microbes.

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