ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Polyester-urethane block copolymers were prepared by the block polyaddition reaction of diisocyanate with two kinds of linear polyesters, one of which was polyethylene terephthalate. The melting points of polyester-urethane block copolymers containing more than 30% polyethylene terephthalate are independent of the total molar fraction of the two polyester components, so that the melting point-composition curves are step-shaped. The relation between the second-order transition point of the block copolymer and its composition, on the other hand, is the same as that for a random copolymer. It is observed that some polyester-urethane block copolymers containing 15-50% of polyethylene terephthalate have elastic properties. For example, the 15/85 polyethylene terephthalate/polyethylene adipate-tetramethylene diisocyanate block copolymer has a tensile strength of 240 kg./cm.2 and an elongation of 700%. It may be supposed that these elastic properties are due to the structure of the block copolymer chains: the flexible polymer chains in the amorphous region may be joined to the crystallites of polyethylene terephthalate, so that a type of network structure similar to crosslinking is formed.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1961.070051317
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