The present investigation was carried out to study the effect of type of polyethers as soft segments upon the physical and fiber properties of polyether-polyester block copolymers obtained by polycondensation.
For this purpose, B-PBG block copolymers composed of poly (oxy-1, 4-butylene) glycol (PBG) as a soft segment and-1, 2-polyethylene-1, 2-diphenoxyethane-
p,
p′-dicarboxylate (B) as a hard segment were prepared and their physical and fiber properties were compared mostly with those of B-PEG block copolymers.
The results are summarized as follows:
(1) Though the rates of ester-interchange reaction of polyethers with dimethylester (B
M) as a polyester component were in the decreasing order of PBG>PEG>PPG, no marked difference was observed in their intrinsic viscosity nubers between resulting B-PBG and B-PEG copolymers. The degrees of polymerization of B-PBG and B-PEG were relatively high, whereas that of B-PPG was low.
(2) As for the degree of crystallinity and melting point B-PBG surpassed B-PEG, and this difference increased with the longer polyether chain. This fact might be attributed to the change of compatibilities of polyether chain with polyester chain in the block copolymers.
(3) The difference of compatibility affected the state of amorphous region in the block copolymers. Accordingly B-PBG with low compatibility showed lower softening temperature than B-PEG.
(4) The mechanical properties of the fibers were influenced by their crystallinity. The fiber from B-PBG 1000 had higher tensile strength and Young's modulus, but lower elasticity and elongation than B-PEG 1540 fiber.
(5) T-PBG 1000 using polyethylene-terephthalate (T) as a polyester component had lower melting point, tensile strength and Young's modulus than B-PBG 1000.
From the above experimental results, it was found that the physical and fiber properties of polyether-polyester block copolymers were influenced remarkably by the compatibilities between their hard and soft segments.
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