Silibase is one of the leading & professional manufacturers specialized in producing all kinds of SILICONE BASED new materials.
Silibase technique team always focus on quality first and insist on developing new products.
Silibase people will serve you the best before and after sale.
May 11, 2023
As we all know, organosilicon has good chemical stability and hardly reacts with the active group of epoxy resin. The solubility parameter of 110 Shanghai silicone rubber o=7 8-1, solubility parameter of PDMS o=7 4~8, the solubility parameter of epoxy resin is about 10 9。 The solubility parameters of the two differ greatly, and according to the principle of similar solubility parameters, the compatibility between silicone and epoxy resin is poor. If the two are simply mixed together during modification, the modification effect will be poor due to the high interfacial tension of the two phases and the multiphase separation structure. Therefore, the method of adding transition phases is often used to improve the compatibility of the two. Silicone fired coupling agents are commonly used transition phases, such as the amino and oxygen groups on the coupling agent reacting with the epoxy group and end light group of epoxy resin, and the tibia group of polysiloxane fired to form block structures, improving compatibility and greatly reducing internal stress in the system.
Modify o-cresol epoxy resin with epoxy terminated polydimethylsiloxane. The experiment found that in the resin cured material prepared by direct blending method, the particle size distribution of the dispersed phase of polysiloxane is very uneven, mainly in the form of floating large particles with a particle size of 2-5 µ m. The interface between the two phases is quite smooth. In the cured epoxy resin modified by a copolymer formed by pre reaction of polysiloxane, the average particle size of the dispersed phase of polysiloxane is about 0.4-1 µ m. The particle size distribution is uniform, with a certain thickness of the two-phase interface layer, and there are both protruding particles and pits on the cross-section. Obviously, the preparation method of polysiloxane modified epoxy resin has a significant impact on the microstructure of the cured epoxy resin. When the copolymer formed by pre reaction is used as modifier, because the PDMS chain segment is connected with the resin matrix by chemical bond, there is strong interaction between the two-phase interface, the size of the formed polysiloxane micro area is small; When using blending modification, although polysiloxane has epoxy groups that can react with phenolic resin, due to the incompatibility between polysiloxane and the matrix resin, the reaction takes place between the two phases during the curing process. The epoxy group in the polysiloxane molecule has little chance of participating in the reaction, and most of the polysiloxane still exists in the form of silicone oil.
In addition, there is another method to improve the compatibility of the two phases: CD causes the organic silicon and epoxy resin to form block II first! Copolymer, then used as a modifier to improve the compatibility between organic silicon and epoxy resin. At this time, the function of the copolymer is similar to that of a surfactant, which can disperse organic silicon in the form of particles in the epoxy resin, thereby improving toughness Improve the polarity of silicon oxide side groups to improve compatibility Prepare polysiloxane sintered particles, mix them into epoxy resin, and crosslink and cure to improve compatibility The synthesis of particles with nuclear structure from octamethylcyclotetrapolysiloxane and acrylic acid monomers can improve compatibility. At the same time, due to the plasticization of the cross-linking network by polysiloxane, the flexibility and mobility of the molecular chain are increased, and the resistance of epoxy curing in the system is reduced, resulting in an increase in the curing reaction rate.
Modified epoxy resin with aminopropyl terminated polyvinylmethyl siloxane. The results of OMA and DSC indicate that the introduction of allyl groups increases the compatibility of the two phases, and as the molecular weight and percentage content increase, the interphase compatibility decreases. The tensile results indicate that the elongation at break of the poly (propyl methyl) siloxane modified system is significantly higher than that of the corresponding PDMS modified system.
Using N, N '- dimethylaniline as a promoter to modify epoxy resin. N. N '- dimethylaniline can not only induce the polarization of light groups and enhance reaction activity in the reaction, but also improve the compatibility between silicone rubber and epoxy resin, resulting in a macroscopic homogeneous epoxy silicone rubber system. The impact strength and shear strength of samples before and after modification are listed in Table 3-18. It can be seen that both the impact strength and shear strength of the sample modified with end shank based epoxy resin are higher than those of pure epoxy resin.
Our main products are Methyl MQ Silicone Resin Powder，MQ Methyl Silicone Resin Liquid，MQ Silicone Resin，MQ Silicone Resin Powder，Liquid MQ Silicone Resin ，Vinyl MQ Silicone Resin，Heat Resistance Silicone Resin.