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

Abstract

Poly(butylene 1,4‐cyclohexanedicarboxylate), an aliphatic polyester with favorable properties, such as resistance to weather and potential biodegradability, has been synthesized with different cis/trans ratio of the 1,4‐cyclohexylene ring. The samples show high degradation temperatures, independent of the stereochemistry of the aliphatic ring. Instead, glass transition temperature, crystallization and melting behavior are strongly influenced by the cis/trans ratio. The trans isomer, more rigid and symmetric than the cis, favors higher transition temperatures and crystallizability. The DMTA spectra present two secondary relaxations, attributed to the (CH2) unit and aliphatic ring motions, which can be beneficial for improving impact resistance properties. The physical properties are compared with those of PBT and PCCD.magnified image

New eco-friendly random copolyesters based on poly(propylene cyclohexanedicarboxylate): Structure-properties relationships

“…As regards the attribution of the * relaxation to a molecular motion, as reported in the literature [5], this relaxation originates from the chair-boat-chair conformational transition of the cyclohexylene ring. Indeed, the cyclohexylene rings in chair conformations can transform form chair to chair via an intermediate twist boat conformation [17].…”

“…The +, process can be related to a rigid confined amorphous phase, analogously to another similar copolymeric systems previously investigated by some of us [16]. Concerning the identification of the molecular origin of the " relaxation, it can be traditionally associated with restricted motions of the chain in polymers with aliphatic sequences: in particular, the relaxation is generally attributed to rotations of the methylene units of glycol sub-unit which is the flexible part of the repeating unit [5].…”

“…Within the polyester class, poly(alkylene 1,4-cyclohexanedicarboxilate)s offer various advantages: the introduction of cycloaliphatic units to the main chain of the polymer can be a way to increase the rigidity of the macromolecular chains. Moreover, conformational transitions of cyclohexylene rings in the backbone originate secondary relaxations in dynamical mechanical spectrum, which contribute to improve the performances of the materials [5]. The synthesis and properties of polyesters and copolyesters containing these cycloaliphatic units were studied at the beginning of the eighties by Eastman Chemical Company, interested to develop materials with excellent tensile strength, stiffness and impact properties as well as materials to be used as improved hot melt adhesives.…”

Resorcinol: A potentially bio-based building block for the preparation of sustainable polyesters

“…34 For this reason, two different isomeric mixtures have been tested (100% and 66% trans). Dimethyl terephthalate, dimethyl isophthalate and furan dicarboxylic acid have been chosen in order to introduce aromatic units also in the diacid, which generally provides high thermal and mechanical performances.…”

Structure–property relationship of poly(cyclohexane 1,4‐dimethylene terephthalate) modified with high trans‐1,4‐cyclohexanedimethanol and 2,6‐naphthalene dicarboxylicacid

“…also effectively controlled the thermal properties and crystal structure of poly(cyclohexane 1,4‐dimethylene 2,6‐naphthalene) (PCN) polymer by controlling the cis−/trans‐configuration of CHDM . Not only thermal but mechanical and barrier properties of polymers are directly influenced by the stereochemistry of CHDM …”