Ethylene Glycol Terephthalate/Diethylene Glycol Terephthalate Copolymer
I. Physical Properties of the Copolymer
1965 Volume 22 Issue 247 Pages 679-685
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1965 Volume 22 Issue 247 Pages 679-685
Studies were made on the physical properties of ethylene glycol terephthalate/diethylene glycol terephthalate [PET/(DEG) T] copolymer over the entire range of copolymerization composition.
(a) The copolymer having the mole fraction of (DEG) T greater than 0.5 shows rubber-like elasticity. Although P (DEG) T has heretofore been obtained only in crystalline state, it crystallized under severe conditions (60°C, 10hr, in solvent). The X-ray diffraction patterns indicate the formation of a new crystalline polymer different from PET.
(b) The melting point Tm of the crystalline PET/(DEG) T copolymer conforms of Flory's equation. The heat offusion is approximately 2793 cal per ET unit.
(c) The glass transition point of PET/(DEG) T is given by Gordon-Taylor's equation:
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where w2 is the molar fraction of PET, K is a constant equal to 0.685.
(d) The relation between the specific volume of the amorphous copolymer and its composition shows that the free volume increases with the mol fraction of (DEG) T.
