脂肪族水性聚氨酯的力学性能研究

考察了软段的种类、分子量大小、混合软段的组成对产物力学性能的影响作用。同时还研究了二羟甲基丙酸(DMPA)用量以及中和剂的影响作用．实验结果表明。软段结构对脂肪族水性聚氨酯成膜的力学性能影响很大，聚酯型产物具有较高的模量和拉伸强度。聚醚型产物则具有较高的伸长率．混合软段对产物力学性能的影响较为复杂，随着软段中聚醚含量的升高，产物的硬度和模量均大幅度下降，但拉伸强度和伸长率的变化并不是一个线性关系．产物的模量随软段分子量的提高而降低，但伸长率和拉伸强度却有所提高．当DMPA用量较高时。产物的模量和拉伸强度均较高：当DMPA用量较低时，产物则具有较高的伸长率．中和剂的种类对产物力学性能的影响明显，当以NaOH为中和剂时，产物具有较高的硬度、模量、拉伸强度：以三乙胺为中和剂时，产物具有较高的伸长率．

THE INVESTIGATION ON THE MECHANICAL PROPERTIES OF WATERBORNE POLYURETHANES

A series of aliphatic waterborne polyurethanes were prepared from isophorone diisocyanate (IPDI), dimethylolpropanic acid (DMPA), poly(butylene adipate) (PBA) and polypropylene glycol (PPG). The COOH groups were neutralized by triethylamine (TEA), NaOH. The effects of soft-segment structure and molecular weight, DMPA amount, neutralizer on mechanical properties of the emulsion cast films were investigated. The experimental data showed that the mechanical properties of WBPU films depend heavily on the structure and molecular weight of soft segments. Polyester-based WBPU displayed much better physical properties than those of polyether-based WBPU. The former showed higher hardness, Youngs modulus and tensile strength due to stronger forces between the macromolecular chains, while the later showed higher elongation. As the molecular weight of soft segments increases, Youngs modulus of WBPU films decrease, while elongation and tensile strength increase. In the case of mixed soft segments, hardness and Youngs modulus decrease rapidly with increasing of polyether content, but the variations of elongation and tensile strength were complex. DMPA amount also influences the mechanical properties of WBPU films. As DMPA amount increases, Youngs modulus and tensile strength of WBPU films increase, while elongation decrease. Neutralizers strongly affect the physical properties of WBPU. NaOH leads higher hardness, Youngs modulus and tensile strength, while TEA leads higher elongation.