Polyesters are of great importance as synthetic fiber materials. The first fiber forming polyerster was developed by Dickson and Winfield in 1941. It was produced by condensation of ethylene glycol and terephphalic acid. The manufacturer product was brought by ICI, because fiber was not marketed until 1948. The ICI product was named ‘Terylene’.
The british polyester “Terylene” is made by polymerizing the diethyl-terephphalic acid and ethylene glycol:
Properties of polyester:Tenacity: Polyester fiber is strong because of their highly crystalline polymer system. It allows the formation of very effective Van Der Waals forces and very weak hydrogen bonds, resulting very good tenacity of polyester filaments. Tenacity 4.5-5.5 g/d.
Elastic- plastic nature: Due to crystalline polymer system of polyester, it feels stiff and hard handle. The crystalline prevents the polymer from bending as a result it will not wrinkle or crease. Elastic recovery is 2-5%.
Hygroscopic nature: Polyester filaments are hydrophobic, the lack of polarity and the extremely crystalline structure resist the entry of water into polymer system. Moisture regain is 0.4%.
Thermal properties: Polyester filaments are low heat conductive and low heat resistance. The melting point is 260-270oC and the glass transition temperature is 70oC.
Effect of acid: Polyester filaments are resistant to acid hydrolysis.
Effect of sunlight: Prolong exposure of sunlight it caused the strength loss of polyester. The graphical figure represents after 1000 hr exposure to sunlight approximately 60-70% loss of strength.
Effect of alkali: Due to alkaline condition polyester may hydrolysis their ester groups. So, polyester is sensitive to alkali.
Here,
A = Feed of ethylene glycol & terephphalic acid
B = Esterification vessel
C = Condense water collector
D = Pre- polymerizing vessel
E = Condense water and glycol collector
F = Polymerizing vessel
G = Condense glycol collector
H = Extruder
I = Spinnerate
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