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Indexed by:期刊论文

Date of Publication:2017-07-01

Journal:EUROPEAN POLYMER JOURNAL

Included Journals:SCIE、EI、Scopus

Volume:92

Page Number:71-85

ISSN No.:0014-3057

Key Words:Aliphatic copolyesters; Cocrystallization behavior; Inclusion-exclusion model

Abstract:Four series of random aliphatic copolyesters derived from 1,6-hexanediol and different diacids were designed and synthesized to investigate the effect of chain length of aliphatic diacids on miscibility and competition of cocrystallization behavior. Isodimorphic behaviors were observed from DSC, WAXD and SAXS analyses for the four series of copolyesters. Crystal type transition point at isodimorphism depended on the chain length of comonomeric diacid units in copolyesters, which presented a crystallization competition effect between the two crystal types of parent homopolyesters. The comonomeric diacids with longer chain length had stronger competitive ability in controlling the cocrystallization even when they were present in a minor proportion. Then, the cocrystallization miscibility was qualitatively analyzed by WAXD and SAXS, and further quantificatively investigated by the defect Gibbs energy calculated from the Wendling-Suter method. For HS unit (hexamethylene succinate) incorporated into the crystal type of HL unit (HA, HSu, HSe or HD unit whose chain length of comonomeric diacids gradually lengthens compared to HS unit), the HL with longer chain length has better miscibility with the inserted HS unit. For HL unit squeezed into the crystal lattice of HS unit, HS unit has worse miscibility with the longer inserted HL unit. Moreover, the chain length inclusion-exclusion model on the basis of the Wendling and Suter theory is proposed to give an insight into the mechanism of how does the chain length of comonomers regulate the cocrystallization behavior.