含羟胺基团的多烷氧基硅烷偶联剂增强聚硫密封胶研究

Modification of polysulfide sealant with multi-alkoxyorganosilane coupling agents with hydroxyl-amine group

用γ-氨丙基三乙氧基硅烷(KH550)和γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)合成了含羟胺结构的多烷氧基硅烷偶联剂.研究了这种复合型的具有羟胺基团和多烷氧基团的硅烷偶联剂对聚硫-金属氧化物体系密封胶力学性能的影响.研究结果表明,只要在体系中加入1%左右的含羟胺结构的多烷氧基硅烷偶联剂,就可以将聚硫密封胶的扯断强度提高70%,断裂伸长率提高30%以上.和钢的粘合性能也提高50%以上.动态力学分析显示,加入这种硅烷偶联剂后,玻璃化温度提高了5℃,这应该是含羟胺基团的多烷氧基硅烷加入后,增加了体系的交联点.这种复合型硅烷偶联剂的加入,还提高了聚硫橡胶的耐水性,对耐油性则没有影响.

Polysulfide sealants have high resistance against ultra violet radiation and environment,exhibit good low-temperature properties,low water-vapor transmission,and resist against solvents and chemicals.They were many publications on the characterization of metal peroxides-cured polysulfide,reporting the results of thermogravimetry analysis,dynamic mechanical analysis,tensile strength and hardness test.Although the polysulfide rubber has the advantage of lower cost,they faced the strong challenges from silicone and polyurethane-based sealants.One of the main reasons is their relatively poor tensile properties and weak adhesive strength.The new multi-alkoxyorganosilane coupling agents with hydroxyl-amine group（MAGHA）are synthesized by addition of γ-aminopropyltriethoxysilane（KH550） and γ-glycidoxypropyltrimethoxysilane（KH560）.The influence to the polysulfide sealants by the multi-alkoxyorganosilane coupling agents with hydroxyl-amine group as additive are studied.With a small amount of MAGHA,the commercial polysulfide-based sealants have significant improvement in mechanical properties.In our polysulfide composition,the methoxy or ethoxy can be reacted with hydroxyl on the surface of the filler.Hydroxy group of the new multi-alkoxyorganosilane coupling agents or water produced by oxidation between polysulfide and MnO2 can make MAGHA to create the three-dimensional structure of polysiloxane through MAGHA polycondensation.The three-dimensional structure of polysiloxane has ability to package the surrounding of fillers and enhance the chain of polysulfide sealant through interreacted pendent with hydroxyl-amine group of MAGHA which can improve the tensile strength and ultimate elongation of sealant simultaneously.The test results show that 1% of multi-alkoxyorganosilane coupling agents with hydroxyl-amine group could help increasing 30% in the ultimate elongation and 70% in the tensile strength of the polysulfide sealants.The adhesive strength to steel also increased significantly.Since MAGHA reinforcement significantly increased the bulk tensile strength of polysulfide sealants,while MAGHA has the special hydroxyl-amine structure,which is the foundation of epoxy resin for its high properties of adhesive.When KH560 added to polysulfide sealants,the adhesive strength has no significant changed.Dynamic mechanical thermal analysis shows the Tg of polysulfide sealant have increased about 5℃.It may due to the increased cross-link by the result of the new multi-alkoxyorganosilane coupling agents with hydroxyl-amine group effect to —SH and fillers.The movements of main chain are limited.It also increased the ability on water.From water absorption test,the polysulfide sealants added MAGHA appear excellent properties of water absorption and resistance.After 18-day immersion,the polysulfide sealants before modification absorbed more than 6.10% water,but only absorbed 4.20% water after modification.This due to the siloxane structure surrounding filler.And the results indicate that the introduction of the MAGHA has no appreciable influence on oil resistance of polysulfide sealants.This new kind multi-alkoxyorganosilane coupling agents with hydroxyl-amine group have the similar effect of modification to the other resins are expected.The continue work are going on.