Copolyesters based on poly(butylene terephthalate)s containing cyclohexyl groups: synthesis, structure and crystallization

Abstract

Poly(butylene terephthalate‐co‐cyclohexylene dimethylene terephthalate) copolymers PBTCT, were synthesized by melt condensation with compositions ranging from 94/08 to 23/77. 13C NMR spectroscopy was used to study the microstructure of the copolyesters and was found to be completely random. The melting temperature, crystallization temperature on cooling, enthalpy of melting and crystallization followed an eutectic behaviour. Thermal and x‐ray diffraction studies indicated that the copolyesters in all composition could crystallize. The XRD studies further indicated that PBT rich copolyesters in the range 75 to 100% BT, crystallized in the PBT lattice while the copolyesters rich in PCT having 38 to 100% CT, crystallized in the PCT lattice.

Structural and thermal properties of poly(1,4-cyclohexane dimethylene terephthalate) containing isosorbide

“…1 The ring structure of 1,4 cyclohexanedimethanol (CHDM) at room temperature flips from the e,etrans cyclohexylene ring to form an a,a-trans cyclohexylene ring via a twisted-boat structure. 6,[12][13][14] Sivaram et al 15 have resolved the high processing temperature problem by synthesizing a random copolyester of PCT and poly(butylene terephthalate) (PBT). 1,[3][4][5] However, one problem lies with its rigid structure, which gives rise to a high melting temperature (T m ) (278-318°C) compared to other conventional polyesters (PET: 250°C and PBT: 225°C).…”

Cocrystallization of poly(1,4-cyclohexylenedimethylene terephthalate-co-hexamethylene terephthalate) copolymers

“…Consequently, the synthesis of PCT-based copolymers or reactive blending with other polyesters have been studied to improve their processibility as well as thermal and mechanical properties through variation of the copolymer composition. [7][8][9][10][11] It is well-known that, in most copolyesters where both A and B components are crystallizable, the degree of crystallinity decreases with increasing the composition of minor component, and as a result the copolymers often become totally amorphous even at low comonomer content. If two crystallizable components of the copolymers are compatible in their crystal lattices (i.e., cocrystallization), thermal and mechanical properties of the copolymers can be controlled without significant loss of crystalline properties.…”

“…If two crystallizable components of the copolymers are compatible in their crystal lattices (i.e., cocrystallization), thermal and mechanical properties of the copolymers can be controlled without significant loss of crystalline properties. [10][11][12][13][14][15] Yoo et al 9 reported that poly(1,4-cyclohexylenedimethylene terephthalate-co-ethylene terephthalate) copolymers, in which ethylene terephthalate (ET) units can crystallize with complete rejection of 1,4-cyclohexyleneterephthalate (CT) units from the crystal whereas CT units can cocrystallize with ET units to some extent, exhibits cocrystallization. However, copolymers with the middle range of comonomer content are completely amorphous.…”

“…It has been recently reported that poly(1,4-cyclohexylenedimethylene terephthalate-co-butylene terephthalate) copolymers can cocrystallize over all the copolymer compositions. 10,11 Since the repeat length of hexamethylene unit in poly (hexamethylene terephthalate) (PHT) matches well with that of the cyclohexylenedimethyl unit in PCT, it is likely expected that poly(1,4-cyclohexylenedimethylene terephthalate-co-hexamethylene terephthalate) (P(CT-co-HT)) copolymers may exhibit cocrystallization. In this study, therefore, we synthesized P(CT-co-HT) with various copolymer compositions from 0 to 100 mol% HT, characterized their chain structure using 1 H NMR spectroscopy, and investigated their thermal property and cocrystallization behavior by using differential scanning calorimetry and wide-angle X-ray diffraction.…”

Influence of Molecular Structure and Stereochemistry of the 1,4‐Cyclohexylene Ring on Thermal and Mechanical Behavior of Poly(butylene 1,4‐cyclohexanedicarboxylate)

“…However, in order to improve certain properties of these polymers numerous modifications of their chemical structure have been proposed: copolymerization, blending with other polymers, and use of additives. In particular, recently there has been great interest in exploring the effects of the introduction of 1,4‐cyclohexylene rings into the polyester chains 2–11. The cycloaliphatic units can partially or totally substitute the aromatic groups or the aliphatic moieties, causing important variations in the properties of the starting materials.…”