Study On The Influence Of Extenders In Transesterfication Process To Synthesize Polycarbonate Polyurethane

Polyurethane elastomer is a kind of high performance polymer material, which is used in many fields in our life. In this thesis,1,6-hexamethylene dicarbamate (HDU) and polycarbon-ate diols (PCDL) are used as raw materials to synthesize linear polyurethane elastomer by one-step non-isocyanate method, avoiding phosgene and isocyanate in traditional process. This process is green, environment friendly and no pollution, and it is of bright future.In this paper, process optimization when using extenders was focused, and the influence of combined catalyst on the products performance was discussed in detail. After characterizei-ng the products, the results showed:the preference to add chain extender was on the time after prepolymerizing40min, BDO was an optimum chain extender, raw materials ratio of n (HDU):n (PCDL):n (Extender) was1:0.7:0.3, the preferred pre-polymerization temperature was105℃, polycondensation temperature was185℃, polycondensation time was4h, then the viscosity of synthesized PU reached61.56mL/g, and the average molecular weight was up to73959with PD as1.7285which proved the product have narrow molecular weight distribution. It was also found that the hardness of polyurethane elastomer was associated with the ratio of raw materials, and the tensile strength and elongation at break were associated with the extender chain structure. The molecule chain was longer, and the product mechanical properties were better. But the product was of poor thermal stability. However, the addition of titanium(IV) ethoxide could improve the thermal stability.