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May 16, 2023
Preparation of physically modified resin: E-20 is heated and melted at 90 ° C, and then DC 3074 and a certain proportion of solvent are added to obtain a stable light yellow transparent solution with a solid mass fraction of 50%. m (E-20): m CDC-3074)=7:3, and this modified resin is named ED-30 (PM).
913cm-1 and 1246cm-I are the characteristic absorption peaks of symmetric and asymmetric stretching vibrations of the epoxy group, respectively. Compared with E-20, the absorption at ED-30 (CM) remains basically unchanged, indicating that the epoxy group did not participate in the reaction; The newly appeared 1100~lOOOcm-1 absorption peak in the ED-30 (CM) diagram is partially obscured by the stretching vibration peak of Si-0-Si (1090~1020cm-1), which corresponds to the sl-O-C generated by the thousand reaction; There is a characteristic absorption peak of Si OC ratio at 2834cm-1 in the DC-3074 spectrum, while this absorption peak completely disappears in the ED-30 (CM) spectrum. The above indicates that OC-3074 and E-20 are not simply physical blends, but have undergone graft polycondensation.
From GPC analysis, it can be seen that E-20 and DC-3074 are composed of prepolymers with various degrees of polymerization, and their relative molecular weight is polydispersible. Compared with before the reaction, the relative molecular weight of ED-30 (CM) is significantly increased, and its distribution range is also significantly widened and evenly distributed. The molecular weight of ED-30 (CM) is Mn=980, Mw=3693, and its dispersion coefficient is 3 The relative molecular weight of 767 is mainly concentrated in the range of 3000-5000, accounting for about 60% of the total amount. This further indicates that organic silicon grafting has modified epoxy resin.
According to TEM analysis, it can be seen that the transmission electron microscopy images of the cured resin obtained from physical modification (PM) and chemical modification (CM) are at 7000 times lower. (a) The black epoxy resin cured product cannot form a continuous phase, and the PMPS and epoxy resin phases are clearly separated, resulting in poor interaction between the two phases; Under the same conditions, the chemically modified resin cured product (b) forms a homogeneous continuous phase, indicating that through chemical modification, the PM matrix is connected to the epoxy resin matrix through S-type 0-C bonds, forming an interpenetrating network structure, resulting in the refinement of the PM dispersion phase without phase separation. Therefore, chemical modification is superior to physical modification.
A homogeneous and stable modifier is prepared by copolymerizing an organosilicon oligomer with a certain degree of miscibility and reactivity with a medium molecular weight epoxy resin. As the proportion of organic silicon increases, the heat resistance of the copolymer is improved, but the oil resistance, solvent resistance, and especially the film-forming ability of the cured product decrease; When the proportion of epoxy resin increases, the opposite is true. Yao Kangde et al. recycled the tibial terminated polymethylphenylsiloxane CPMPS and bisphenol A epoxy resin (EP) through dehydration condensation to obtain a PMPS/EP graft copolymer, which can effectively improve the compatibility between PMPS and EP, as well as the heat and water resistance of the coating.
Our main products are Acrylic Modified Silicone Resin Emulsion，Epoxy Modified Silicone Resin Emulsion，Smokeless Silicone Resin，Self-drying Silicone Resin，Highly Active Silicone Resin，Methyl Silicone Resin Intermediate.