| CaCO3 is widely used in room temperature vulcanized silicone rubber(RTV V silicone rubber)as extender and semi-reinforcing filler.The uniformity of the filler in the rubber matrix is closely related to the performance of the product.So it is significant to grasp and improve the dispersion state of the filler.Currently,in order to improve the dispersion of CaCO3 filler in rubber matrix and improve the properties of rubber materials,the most widely used method is to modify CaCO3 with stearic acid.Because of a large difference of solubility parameter between stearic acid and silicone rubber,their compatibility is not very well.The performance improvement of silicone rubber which filled stearic acid modified CaCO3 is limited.So the carboxyl terminated silicone oil was synthesized and applied it into to RTV silicone rubber which filled CaCO3.In the first part of this thesis,four kinds of CaCO3 which come from different manufacturers are used to prepared silicone rubber samples.The dispersion state of filler is Characterized by electron microscope,and the effect of CaCO3 particle size,surface morphology and surfactant content on the dispersion of CaCO3 in silicone rubber was analyzedIt was found that both strain sweep and temperature sweep of rotational rheometer can reflect the dispersed state of the filler..The dispersion index of the samples was calculated to quantitatively evaluated the dispersion state of filler,the technical indexes for evaluating the dispersion state of CaCO3 are summarized.In the second part of this thesis,two kinds of carboxyl terminated polydimethylsiloxanes(carboxyl silicone oil)with different molecular weight were synthesized by the reaction of hydrogen addition and hydrolysis.The carboxyl group on the silicone oil has reactivity with hydroxyl group on the surface of CaCO3,and it has high compatibility with silicone rubber.The carboxyl silicone oil was appiled to CaCO3 filled silicone rubber,and the effects of carboxyl silicone oil on the rheological and mechanical properties of silicone rubber were investigated.It was found that carboxyl silicone oil can effectively reduce the formation of filler network structure,Improving the uniformity of CaCO3 in silicone rubber.Carboxyl silicone oil can improve the elongation and hardness of silicone rubber,and the tensile strength can be increased more than 20%.Carboxyl silicone oil has little effect on the tensile strength of stearic acid modified CaCO3 filled silicone rubber,and has plasticizing effect to the silicone rubber.Temperature sweep was used to study on the storage stability of uncured RTV silicone rubber.It was found that the samples which contain carboxyl silicone oil had better storage stability before 60?,low molecular weight carboxyl silicone oil has better effect on improving storage stability. |
PDF Full Text Request