Preparation And Characterization Of Functional Polyurethane Elastomers

Polyurethane elastomer is a kind of polymer material with high strength and elasticity,wear resistance,tear resistance,pourability and other characteristics.Polyurethane can be obtained from rigid plastics to soft elastomer products by changing different formulations.Despite the possibility of tailoring their properties according to requirements,polyurethane suffer a seriously poor stability towards heat.Also as damping materials,the useful damping temperature range of polyurethane elastomer usually covers 20–30?which is rather narrow for practical applications.In this paper,a novel chain extender(BIAG)of polyurethane with imide ring was successfully synthesized.The structure of BIAG was confirmed through FTIR,~1H-NMR analysis.The effect of the proportion of the chain extender BIAG on the tensile properties and hardness of the polyurethane elastomer was studied.At the same time,the effects of different ratios of BIAG content of PU samples on the DIN volume wear were investigated.The results show that the addition of BIAG can significantly improve the wear resistance of PU samples which the volume wear loss is changed from unmodified 83mm~3 to about 15mm~3.Meanwhile the surface morphology of the samples after DIN abrasion was observed by scanning electron microscopy(SEM).It was found that the surface of the BIAG modified PU samples was relatively smooth,the wear marks were not obvious.Finally,the thermal stability of PU modified by BIAG was investigated by TGA.The results showed that the thermal decomposition temperature of modified PU was increased by about 30°C.In this paper,the damping effect of polyurethane elastomers was investigated from the aspects of the composition of soft segment and the content of hard segment.Meanwhile,the hyperbranched polyol(S-HBP)with long side chains was synthesized as a cross-linking agent.Also the effect of the content of long side chains in S-HBP on the damping effect of polyurethane elastomer was investigated.It is customary to take the temperature range(tan?>0.3)as a standard to evaluate the dynamic mechanical properties of damping materials.The dynamic mechanical analysis(DMA)tests showed that the neat TPU matrix exhibited only one relaxation transition at about-30?.This relaxation was the glass transition of the soft segments.S-HBP was mixed with polyurethane oligomers synthesized from MDI and PPG-2000 to obtain modified polyurethanes(S-HBP/PUs).Compared with the neat TPU,all the S-HBP modified PU showed very broad overlapping double tan?peaks(about 120?wide).The low temperatures peak was related to the glass transition of the soft region and the high temperature peak(novel peak)corresponded to the glass transition of the hard phase.The dynamic mechanical analysis(DMA)tests shows that the tan?value were 1.15 and its temperature range(tan?>0.3)from-36?—83?,which was much better than the damping property of PU/TMP.Moreover,with the increase of S-HBP loading,the tan?value increased slightly and the temperature range(tan?>0.3)became more wide.At the same time,the glass transition of the hard phase became more and more distinct and strong.As expected,S-HBP has a more significant effect on the mechanical properties.The values of tensile strength and the hardness of S-HBP/PUs are much lower than the PU/TMP.When the S-HBP contents were 30%and 50%,the elongation at break of the H-PUs increase by 486%and 736%compared to the PU/TMP,respectively.