功能化纳米SiO_2/热塑性弹性体复合材料的制备及性能

Preparation and Characterization of Functional Nano-silica/Thermoplastic Elastomer Composites

采用甲苯-2,4-二异氰酸酯(TDI)改性纳米二氧化硅(SiO_2),制备表面接枝有TDI的功能化纳米SiO_2(TDI-SiO_2),再将其分散于4,4'-二苯基甲烷二异氰酸酯中,经原位聚合法制备纳米SiO_2/热塑性聚氨酯弹性体(TPU)复合材料。利用红外光谱仪、差示扫描量热仪、X射线衍射仪、扫描电子显微镜、维卡软化温度测定仪和拉力试验机等手段,表征和分析了复合材料的结构、热性能、结晶性及力学性能。结果表明,TDI成功接枝改性纳米SiO_2;纳米填料TDI-SiO_2的加入使TPU体系的微相分离程度减弱,其异相成核作用提高了TPU硬段相的结晶性能;相比纯TPU基体,复合材料抗热变形能力显著提高,当TDI-SiO_2质量分数为1%时,复合材料的维卡软化温度提高了近60℃;复合材料力学性能明显提高,与纯TPU相比,拉伸强度最大提高约24 MPa,断裂伸长率最大提高了23%,说明纳米TDI-SiO_2具有既增强又增韧的作用。

Functional nano-silica （TDI-SiO2 ） was prepared by grafting 2, 4-di-isocyanate （TDI） onto the surface of SiO2. Then a series of SiO2/thermoplastic polyurethane elastomer （TPU） nanocomposites with different TDI-SiO2 contents were prepared by prepolymer method via in-situ polymerization. The structure, thermal properties, crystallinity and mechanical properties of SiO2/TPU composites were investigated by means of infrared spectrometer, differential scanning calorimetry, X-ray diffraction, scanning electron microscope, the Vicat softening temperature, and the mechanical properties. The results demonstrate that, TDI is successfully grafted onto SiO2 ; TDI-SiO2 can decrease microphase separation of TPU and improve the crystallinity of hard segment as a heterogeneous nucleation agent; comparing with the pristine TPU, the nanocomposites have excellent resistance to thermal deformation, when the mass fraction of TDI-SiO2 is l wt% , the Vicat softening temperature raises by 60 ℃ ; the mechanical properties of composites enhance markedly, comparing with the pristine TPU, the maximum of tensile strength increases by almost 24 MPa, and the maximum elongation at breaking increases by about 23% , TDI-SiO2 can improve the tensile strength and the elongation at break simultaneously.