硅烷偶联剂对室温硫化氟硅密封剂性能的影响

Effect of Silane Coupling Agent on Properties of RTV Fluorosilicone Sealant

选用6种常见硅烷偶联剂作增粘剂添加到室温硫化氟硅密封剂中,考察了硅烷偶联剂种类对氟硅密封剂施胶性能、贮存稳定性、拉伸性能、粘接性能和耐介质性能的影响。结果表明:加入氨基硅烷偶联剂的氟硅密封剂的贮存稳定性较好,经过加速贮存试验后,挤出时间和表干时间变化均不大;加入环氧基硅烷偶联剂的氟硅密封剂,加速贮存试验后无法挤出,表干时间也从22 min大幅缩短至2 min;丙烯酰氧基硅烷偶联剂和巯基硅烷偶联剂的加入均会降低氟硅密封剂的贮存稳定性,且下降幅度相当;加入脲基硅烷偶联剂的氟硅密封剂经加速贮存试验后,表干时间从29 min缩短至11 min,但挤出时间变化不大,贮存稳定性优于加入丙烯酰氧基或巯基硅烷偶联剂的样品;含巯基偶联剂的氟硅密封剂的拉伸强度和邵尔A硬度最低,为2.2 MPa和49度,其余样品的拉伸性能差别不大;含环氧基硅烷偶联剂和氨基硅烷偶联剂的氟硅密封剂粘接强度较高,剥离强度分别为2.5 kN/m和2.8 kN/m,剪切强度分别为1.5 MPa和1.4 MPa;经湿热老化(85℃、相对湿度85%条件下放置1000 h)后,氟硅密封剂的力学性能和粘接性能均有所下降。含脲基硅烷偶联剂的氟硅密封剂降幅最小,剥离强度保持稳定,剪切强度变化率为-57%。含环氧基硅烷偶联剂的密封剂的剥离强度、剪切强度变化率分别为-82%、-57%,降幅较大;氟硅密封剂在3号喷气燃料或去离子水中浸泡后均发生溶胀,加入硅烷偶联剂对氟硅密封剂的耐介质性能影响较小。

Six kinds of silane coupling agents were added into RTV fluorosilicone sealant as tackifiers.The effects of silane coupling agents on processability,storage stability,tensile properties,adhesive properties and medium resistance of fluorosilicone sealant were investigated.The results show that the fluorosilicone sealant with aminosilane coupling agent has better storage stability.The extrusion time and surface drying time of the sealant changes little after the accelerated storage test.The fluorosilicone sealant with epoxy silane coupling agent cannot be extruded,and the surface drying time is shortened sharply from 22 min to 2 min.The storage stability of fluorosilicone sealant will be reduced with the addition of acryloyloxysilane coupling agent and mercaptosilane coupling agent,with the similar decline.After the accelerated storage test,the surface drying time of fluorosilicone sealant added with urea silane coupling agent is shortened from 29 min to 11 min,but the extrusion time do not change much,and the storage stability is better than that of samples with acryloyloxy or mercaptosilane coupling agent;the fluorosilicone sealant containing thiol coupling agent have the lowest the tensile strength and shore A hardness,which is 2.2 MPa and 49 Shore A.The tensile properties of the others have no difference;the fluorosilicone sealant containing epoxy coupling agent and amino coupling agent has the bonding strength of 2.5 kN/m and 2.8 kN/m respectively,and the shear strength of 1.5 MPa and 1.4 MPa respectively.After aging at 85℃and relative humidity of 85%for 1000 h,the mechanical properties and bonding properties of fluorosilicone sealant decreased.The sealant containing urea silane coupling agent has the smallest decrease,a stable peeling strength,and the change rate of shear strength of-57%.The sealant containing epoxy silane coupling agent has the peeling strength and shear strength change rate of-82%and-57%respectively,with a significant decrease.The fluorosilicone sealant swells after immersion in 3#jet fuel or deionized water,and the silane coupling agent has little effect on the medium resistance of the sealant.