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Fibers from flexible liquid crystal main‐chain polymers. II. Functional copolymers based on the 4,4′‐dihydroxy‐2,2′‐dimethylazoxybenzene mesogen and spacers based on 2‐dodecenedioic and nonanedioic acids
Author(s) -
Lin C. H.,
Maeda M.,
Blumstein A.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070410512
Subject(s) - mesogen , thermotropic crystal , materials science , copolymer , comonomer , liquid crystal , crystallization , polymer chemistry , tenacity (mineralogy) , polymer , moiety , ultimate tensile strength , mesophase , modulus , composite material , liquid crystalline , organic chemistry , chemistry , optoelectronics
Abstract Fibers spun from liquid crystalline solutions or melts are characterized by a high degree of chain alignment which promotes high values of tenacity and tensile modulus in the direction of fiber axis but lower values in the transversal direction. Structural modifications are introduced into the flexible moiety and the mesogenic group to alleviate this shortcoming. The incorporation of a spacer based on 2‐dodecenedioic acids into a thermotropic liquid crystalline polyester was studied. A phase diagram was established to optimize the composition of such copolyesters. A significant increase in mechanical properties on crosslinking through UV irradiation was observed. A remarkable property of such systems is the retention of molecular chain order in spite of temperatures in excess of T g . This is valid for both crosslinked and uncrosslinked systems. Remarkable also is the crystallization on annealing of a number of copolymer compositions in spite of a structural difference between the comonomer units.