Thermoplastic polyurethane elastomers based on polycarbonate diols with different soft segment molecular weight and chemical structure: Mechanical and thermal properties

TLDR

Microphase separation between hard and soft segments governs the thermal and mechanical behavior of thermoplastic polyurethane elastomers. The study synthesized thermoplastic polyurethane elastomers with varying polycarbonate diol soft segment molecular weight and chemical structure, as well as hard segment content, to examine their impact on thermal and mechanical properties. The polymers were characterized by dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared‑attenuated total reflection spectroscopy, and mechanical testing. Increasing soft segment length and hard segment content enhanced microphase separation, hard domain order, crystallinity, and stiffness, producing a more developed reinforcing hard domain structure that, together with the elastic soft segments, provided sufficient physical crosslink sites for elastomeric behavior. © 2007 Society of Plastics Engineers, 2008.

Abstract

Abstract A series of thermoplastic polyurethane elastomers based on polycarbonate diol, 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol was synthesized in bulk by two‐step polymerization varying polycarbonate diol soft segment molecular weight and chemical structure, and also hard segment content, and their effects on the thermal and mechanical properties were investigated. Dynamic mechanical analysis termogravimetric analysis, differential scanning calorimetry, Fourier transform infrared‐attenuated total reflection spectroscopy and mechanical tests were employed to characterize the polyurethanes. Thermal and mechanical properties are discussed from the viewpoint of microphase domain separation of hard and soft segments. On one hand, an increase in soft segment length, and on the other hand an increase in the hard segment content, i.e., hard segment molecular weight, was accompanied by an increase in the microphase separation degree, hard domain order and crystallinity, and stiffness. In phase separated systems more developed reinforcing hard domain structure is observed. These hard segment structures, in addition to the elastic nature of soft segment, provide enough physical crosslink sites to have elastomeric behavior. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers