Polyurethane Elastomers Based on Poly(1,3-Propanediol Carbonate) Glycols

A new type of polyol has been developed by Shell Chemical Co. based on the polycarbonate made from 1,3-propanediol. Poly(trimethylene carbonate) glycol of 2000 MW (PTMC 2000) has been characterized by its hydroxyl content (OH number), molecular weight distribution, glass transition temperature and viscosity at different temperatures. The compatibility of PTMC 2000 with 1,3-propanediol (1,3-PDO) and 1,4-butanediol (1,4-BD) chain extenders in the temperature range from RT to 90°C was evaluated. Both the aromatic and cycloaliphatic thermoplastic polyurethane elastomers (TPUs) based on PTMC 2000 were prepared and evaluated. 4,4’-Diphenylmethane diisocyanate (MDI) was utilized in the preparation of aromatic TPUs and methylene bis(4-cyclohexyl isocyanate) (H 12 MDI) in aliphatic TPUs. 1,3-PDO and 1,4-BD were used as chain extenders and the hard segment concentration was varied. As a reference, TPUs based on commercial poly(1,6-hexanediol carbonate) glycol (Desmophen C-200, Bayer AG) were prepared and evaluated. The physico-mechanical properties (hardness, stress-strain, tear resistance, compression set, resilience, and abrasion resistance) of TPUs were measured according to standard ASTM methods. The moisture and solvent resistance (selected organic solvents and dilute acids/bases) were measured by determining the weight change upon immersion. Insight into the morphology of elastomers was obtained by combining different methods of characterization including differential scanning calorimetry (DSC), thermo-mechanical analysis (TMA), dynamic-mechanical analysis (DMA) and Fourier transform infra-red analysis (FTIR). The degree of clarity of the elastomers was also measured.