MQ硅树脂设计合成及增强液体硅橡胶性能研究

Design and Synthesis of MQ Silicone Resin and Research on the Properties of Reinforced Liquid Silicone Rubber

以无水乙醇为共溶剂,采用正硅酸乙酯法合成了系列MQ硅树脂,并用于液体硅橡胶的补强。考察了四甲基氢氧化铵(THMA)碱催化调聚工艺对MQ硅树脂性能的影响,探讨了MQ硅树脂中乙烯基质量分数、MQ硅树脂与气相法二氧化硅质量比等因素对液体硅橡胶性能的影响。结果表明,采用THMA碱催化调聚工艺,可提高MQ硅树脂的数均摩尔质量,降低其乙氧基和羟基含量,提高其对液体硅橡胶的补强效果;随着MQ硅树脂中乙烯基质量分数由0增至0.40%,液体硅橡胶的邵尔A硬度从25度升高到34度,拉伸强度由4.7 MPa提高到6.3 MPa,可见光透过率由81%提高到85%,撕裂强度由11.5 kN/m提高到16.2 kN/m,拉伸永久变形则总体呈下降趋势。MQ硅树脂中乙烯基质量比继续增加,液体硅橡胶的主要性能基本维持稳定;随着补强填料中MQ硅树脂与气相法二氧化硅质量比由0.2∶1增至0.8∶1,液体硅橡胶的邵尔A硬度由34度降至27度,拉伸强度由7.7 MPa降至4.5 MPa,拉断伸长率由750%降至480%,拉伸永久变形由5.6%减小到2.3%,撕裂强度由17.0 kN/m降至12.0 kN/m,可见光透过率由77%提高到87%。MQ硅树脂中乙烯基质量比选择0.40%较佳,MQ硅树脂与气相法二氧化硅质量比选择0.4∶1较佳,此时制得的液体硅橡胶邵尔A硬度为34度,拉伸强度为6.3 MPa,拉断伸长率为630%,拉伸永久变形为2.3%,撕裂强度为16.2 kN/m,密度为1.09 g/cm^(3),可见光透过率为85%。

A series of MQ silicone resins were synthesized by tetraethyl orthosilicate method with anhydrous ethanol as co-solvent and applied in the reinforcement of liquid silicone rubber.The effects of tetramethylammonium hydroxide(THMA)alkali catalytic polymerization process on the properties of MQ silicone resin were investigated.The effects of vinyl mass ratio in MQ silicone resin and the mass ratio of MQ silicone resin to fumed silica on the properties of liquid silicone rubber were discussed.The results show that with THMA alkali-catalytic telomerization process,the number average mass of MQ silicone resin is improved,the content of ethoxy and hydroxyl groups can be reduced,and the reinforcement effect of MQ silicone resin on liquid silicone rubber can be improved.As the mass ratio of vinyl in MQ silicone resin increases from 0 to 0.40%,the Shore hardness of liquid silicone rubber increases from 25A to 34A,the tensile strength increases from 4.7 MPa to 6.3 MPa,the visible light transmittance increases from 81%to 85%,the tear strength increases from 11.5 to 16.2 kN/m,and the tensile permanent deformation generally shows a downward trend.The mass ratios of vinyl in MQ silicone resin continue to increase,and the main properties of liquid silicone rubber remain stable.As the mass ratio of MQ silicone resin to fumed silica in the reinforcing filler increases from 0.2∶1 to 0.8∶1,the Shore hardness of liquid silicone rubber decreases from 34A to 27A,the tensile strength decreases from 7.7 MPa to 4.5 MPa,the elongation at break decreases from 750%to 480%,the tensile permanent deformation decreases from 5.6%to 2.3%,the tear strength decreases from 17.0 to 12.0 kN/m,and the visible light transmittance increases from 77%to 87%.When the mass ratio of vinyl in MQ silicone resin is 0.40%and the weight ratio of MQ silicone resin to silica is 0.4∶1,the prepared liquid silicone rubber has the good comprehensive properties,with Shore hardness of 34A,tensile strength of 6.3 MPa,elongation at break of 670%,tensile set of 2.3%,tear strength of 16.2 kN/m and visible light transmittance of 85%.