Preparation And Properties Of PU And PU/Zeolite Composites With Different Crosslink Density Micro-domains

Polyurethane elastomer (PU) has good elasticity, wearable property, good oil resistance, the ozone(O₃) resistance, microtherm resistance, well viscidity, good mechanical property and electrical resistance and so on. So it has been widely applied in the every area of civil affairs. One of higher mechanical properties is needed for PU elastomer on some occasions, tear resistance or tensile strength. To obtain relationship between crosslink density and tensile strength or tear resistance, we design polyurethane with different crosslink density micro-domains, and the micro-domains form polymer alloy structure. On the other hand, PU/zeolite composites with different crosslink density micro-domains were studied.The prepolymerization method was used to prepare PU with different crosslink density micro-domains and PU/zeolite composites with different crosslink density micro-domains with PEA, TDI, MOCA and zeolite 13X or 4A. The PU materials were characterized by mechanical properties measurement, solvent resistance measurement, DSC, DMA and SEM.The test results of mechanical properties show that when the content of -NCO group in prepolymer is 4.5%, tear resistance strength of PU with different crosslink density micro-domains are increased, tensile strength are decreased and elongation at break are unaltered, compared with homogeneous PU materials. Moreover, tensile strength and tear resistance of PU with different crosslink density micro-domains at the average crosslink coefficient 0.9 are optimum.When the content of -NCO group in prepolymer is 4.5%, PU/zeolite composites with 7% zeolite contented, with different crosslink density micro-domains exhibit higher mechanical properties than homogeneous PU/zeolite composites.The solvent resistance property test reveals that PU with different crosslink density micro-domains has better solvent resistance property. Compared with homogeneous PU/zeolite composites, solvent resistance property of PU/zeolite composites with different crosslink density micro-domains is improved obviously.The DMA results indicate that the storage modulus and the loss modulus of PU with different crosslink density micro-domains both increase, the glass transition temperature(Tg) and the damp modulus both decrease, the microphase separation improve. Besides, the adding of zeolite improves the microphase separation of soft and hard segments.The DSC results verify that crysterization of hard segment of PU with different crosslink density micro-domains increase at 210℃. The filling of zeolite affects on the microphase separation, the crystal type of hard segment of PU/zeolite composites with different crosslink density micro-domains changes.The SEM photographs reveal that the particles of zeolite are dispersed homogeneously in composites.Consequently, PU with different crosslink density micro-domains possess higher tear resistance strength, lower glass transition temperature and damp modulus, better microphase separation. On the other hand, the materials exhibit better solvent resistance property due to the chains with high crosslink density.