Study On Thermal Resistance Of PUE

Polyurethane elastomers (PUE) as a class of synthetic polymer materials with outstanding property,but due to the bad thermal resistance,which were limited the further application in engineering field.In this thesis,introducing a good thermal stability heterocyclic group in the molecular chain like sulfone group,isocyanurate and imide could enhance the heat-resistant property of polyurethane elastomers.First,a polyurethane containing sulfone group was prepared by substituting 3,3'-dichloro-4,4'-diaminodiphenyl methane(MOCA) with 3,3'-diaminodiphenyl sulfone as chain extender.The results showed that the modified PUE had the better heat-resistant properties and higher thermal decomposition temperature by introducing sulfone group. The differential thermo-gravimetirc(DTG) curves for decomposition of m-PUE showed two-stage decomposition. Compared with PUE, the temperature of largest weight loss for m-PUE is more than 6℃.M-PUE had better mechanical properties when 3,3'-diaminodiphenyl sulfone mole fraction was 20% in chain extender.When in the range of high temperature,the tanδof m-PUE is larger than PUE under the same circumstances.Then, polyurethanes wre prepared with the reaction of the -NCO of isocyanate and the–OH of tri(2-hydroxyethyl) isocyanurate(THEIC) introducing isocyanurate(IS) to the main chain of PUE.The results showed that the m-PUE had the better heat-resistant properties and higher thermal decomposition temperature by introducing IS. The DTG curves for decomposition of polyurethanes showed two-stage decomposition. Compared with PUE, the temperature of largest weight loss for m-PUE is more than 16℃. With the increasing of the content of THEIC, tensile strength , elongation at break , tear strength and the hardness of m-PUE was increased.The peak of m-PUE in the T～tanδcurve is broader than that of pristine PU.When in the range of high temperature,the tanδof m-PUE is larger than PUE under the same circumstances.With the increasing of THEIC, the swelling ratio of m-PUE was decreased.Finally, isocyanate was modified by trimellitic anhydride (TMA).Polyurethanes wre prepared with synthesis of prepolymer by introducing imide group.The results showed that it greatly enhanced mechnical properties due to the introducing imide group. The m-PUE had the better heat-resistant properties and higher thermal decomposition temperature. The DTG curves for decomposition of polyurethanes showed two-stage decomposition. Compared with PUE, the temperature of largest weight loss for m-PUE is more than 11℃.It enhanced the glass transition temperature and improved the damping properties.