【作者】 张丽；

【导师】 吕志平；

【作者基本信息】 太原理工大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 聚氨酯（PU）是一种具有氨基甲酸酯链段重复结构的聚合物,具有很好的耐撕裂和耐磨损性,良好的抗臭氧和耐油性,应用广泛。气相二氧化硅（俗称白炭黑）具有粒径小、多孔、比表面积大、表面活性高等特性,可用于改善橡胶制品的性能。聚氨酯/二氧化硅（PU/SiO₂）复合材料具有优良的机械性能和良好的耐热性能。聚氨酯材料的综合性能与其组成的多元醇、多异氰酸酯和扩链剂小分子二胺的种类有关,还与复合材料的微相结构密切相关。扩链剂3, 5-二甲硫基甲苯二胺（DMTDA）与常用扩链剂MOCA相比,有常温下为液体,操作方便的优点,但是文献中报导不多,本文基于扩链剂DMTDA制备了PU/SiO₂复合材料,含有不同交联密度微区的多交联聚氨酯材料,并考察了多交联体系PU/SiO₂复合材料的性能以及不同交联方式对性能的影响。本文以2, 4-甲苯二异氰酸酯（TDI-100）、聚酯多元醇（PEA）、气相SiO₂以及3, 5-二甲硫基甲苯二胺（DMTDA）为主要原料,用预聚法合成了PU/SiO₂复合材料、多交联体系PU材料以及多交联体系PU/SiO₂复合材料,利用SEM、DSC和力学测试考察了材料的性能,并分析了影响材料性能的主要因素。SEM分析表明:SiO₂粒子在PU基体中分散较好。多交联体系PU/SiO₂复合材料的拉伸断裂面呈明显的凹凸不平状态,具有很多纤维状物连接的丘陵状的花纹,这种断裂方式的材料具有更好的韧性和强度。力学性能测试表明:当预聚体中-NCO基团含量为4%左右,加入SiO₂粒子能够明显提高聚氨酯材料的硬度、拉伸强度和耐撕裂性能,但断裂伸长率降低。当SiO₂添加量为3%（相对于多元醇的质量分数）时, PU/SiO₂复合材料的综合性能最优。多交联聚氨酯材料具有比均一聚氨酯材料更好的耐撕裂性能和断裂伸长率,拉伸性能区别不大。多交联PU/SiO₂复合材料具有比均一PU/SiO₂复合材料有更好的耐撕裂性能和断裂伸长率,并保持了PU/SiO₂复合材料良好的拉伸性能。耐溶剂性能测试说明:多交联聚氨酯材料能够改变均一聚氨酯材料的微相结构,改善耐溶剂性能。DSC测试说明:加入SiO₂粒子和通过多交联方式都能够提高聚氨酯材料的耐热分解温度。多交联体系材料微区结构上交联密度差异程度不同影响材料的微相分离和耐热性能。总的来说,多交联体系PU/SiO₂复合材料具有优良的耐撕裂和耐热性能,较好的拉伸性能,还有不错的断裂伸长率和耐极性溶剂性能。另外,本文还考察了扩链剂和多元醇种类对低硬度聚氨酯材料性能的影响。通过力学性能和TG测试表明:在以预聚体-NCO含量为2.0左右制备的低硬度聚氨酯材料中,利用DMTDA为扩链剂制成的材料有较高的硬度,以MOCA为扩链剂制成的材料耐热性能略优。PEA-DMTDA型低硬度聚氨酯材料在扩链系数为0.9时具有最好的力学性能,耐溶剂性能则随着扩链系数的增加而变差。更多还原

【Abstract】 The polyurethane （PU） is a polymer formed with urethane segment, as very high resistance to tear and abrasion, good resistance to ozone, oil and petrol, is widely used. Fumed silica, also called silica aerogel, have small diameters, porous inside the structure, the advantages of a large specific surface and highly activated property, enabled to improve the performance of rubber. Polyurethane/silica （PU/SiO₂） composites have great mechanical and good heat-resistance property. The microstructure, in addition to raw material types, plays a key role to the comprehensive performance of composites. Chain extender 3, 5-dimethyl mercapro toluenediamine （DMDTA） can be used in room temperature, is easier to operation than common chain extender MOCA, but there is a little literature about PU with DMDTA. In this paper, PU and composites with different crosslink density micro-domains were synthesized with chain extender DMDTA. The properties of multi-crosslink PU/SiO₂ composites were investigated and the influence of different crosslink way on these properties was discussed further.In this paper, the PU/SiO₂ composites , multi-crosslink PU and multi-crosslink PU/SiO₂ composites were prepared with pre- polymerization method with the main raw materials of PEA, TDI-100, fumed silica and DMDTA. Properties of these materials were investigated by SEM, DSC and mechanical tests. The main factors which affect the properties were also analyzed.SEM analysis showed that SiO₂ has a good dispersion in PU. The tensile sectional morphology of PU/SiO₂ composite is rough, which leads to absorbing more energy at break and good mechanical properties.The mechanical test results showed that when the content of–NCO group in prepolymer is about 4%, the hardness, tensile strength and the tear resistance properties of PU were greatly improved by loading SiO₂ particle, but the elongation at bresk a little decreased. PU/SiO₂ composites have best over-all performance when the SiO₂ content comes to 3% （based on the mass of polyols）.Multi-crosslink PU materials had much better tear-resistance property and elongation at break, similar tensile strength, compared with homogeneous PU. PU/SiO₂ composites with multi-crosslinking method had better tear-resistance property and elongation, kept good drawing behavior of homogeneous PU/SiO₂ composites.The solvent resistance property test revealed that multi-crosslink PU changed the microstructure, improved the solvent resistance property.The DSC results verified that both adding SiO₂ particles and taking multi-crosslinking way can raise the thermal decomposition temperature. The thermal properties of multi-crosslink PU were much dependent on the differences between crosslink densities of micro-domains.Conclusively, Multi-crosslink PU/SiO₂ composites have excellent tear-resistance and heat-resistance performance, great tensile strength, good elongation at break and solvent resistance properties.The second part work of this paper is that the influences of different extenders and polyols on properties of low hardness PU materials were investigated. Mechanical tests and TG analysis results showed that when the content of–NCO group in pre-polymer is about 2%, PU with extender DMDTA have higher hardness, but lower thermal decomposition temperature than PU with extender MOCA. PU made from PEA and DMTDA have the best mechnical property when the crosslink coefficient is 0.9. But the solvent resistance decreased with increasing crosslink coefficient.更多还原