Influence of Temperature on Mechanical Properties of P(BAMO-r-THF) Elastomer

Abstract

The relationship between temperature and the mechanical properties of an end cross-linked equal molar random copolyether elastomer of 3,3-bis(azidomethyl)oxetane and tetrahydrofuran (P(BAMO-r-THF)) was investigated. During this investigation, the performances of two P(BAMO-r-THF) elastomers with different thermal histories were compared at different temperatures. The elastomer as prepared at 20 °C (denoted as S0) exhibited semi-crystallization morphology. Wide angle X-ray diffraction analysis indicated that the crystal grains within elastomer S0 result from the crystallization of BAMO micro-blocks embedded in P(BAMO-r-THF) polymeric chains, and the crystallinity is temperature irreversible under static conditions. After undergoing a heating-cooling cycle, this elastomer became an amorphous elastomer (denoted as S1). Regarding mechanical properties, at 20 °C, break strains and stresses of 315 ± 22% and 0.46 ± 0.01 MPa were obtained for elastomer S0; corresponding values of 294 ± 6% and 0.32 ± 0.02 MPa were obtained for elastomer S1. At −40 °C, these strains and stresses simultaneously increased to 1085 ± 21% and 8.90 ± 0.72 MPa (S0) and 1181 ± 25% and 10.23 ± 0.44 MPa (S1), respectively, owing to the strain-induced crystallization of BAMO micro-blocks within the P(BAMO-r-THF) polymeric chains.

Overlooked Impact of Interchain H-Bonding between Cross-Links on the Mechanical Properties of Thermoset Polyurethane Elastomers

“…However, the systematic analysis of the mechanical properties of polyurethane thermosets is not as rich as that of TPE. The majority of the strategies on tuning their mechanical properties have been focused on adjusting the cross-linking density, SS prepolymer modification and blending, mixing of cross-linkers and curing agents, and so on. − The cross-linking density was usually reported to be varied by changing the molar ratios of the isocyanate group to the hydroxyl group (NCO/OH). , The chain length, composition, and structure of the soft segment also played important roles in modulating the properties of polyurethane thermosets. ,− In terms of HS structure, many other works have been focusing on constructing elastomer networks based on various types of polyol cross-linkers or isocyanate cross-linkers, including employing a mixture of aliphatic and aromatic isocyanates instead of only one type. ,− …”