Expanded monomer modified epoxy resin
What is expanded monomer modified epoxy? The double-six-membered spiro compound (1) has a volume expansion of 2% when polymerized at 142°C, the compound (2) has a volume expansion of 8% when polymerized at 82°C, and the compound (3) polymerizes at 100°C The volume expansion degree is 7g. The copolymerization of the expansion monomer and the epoxy resin can reduce the volume shrinkage during the curing of the epoxy resin, which is beneficial to improve the bonding strength of the adhesive. So far, many expansion monomers have been found, such as helical orthocarbonates, bicyclic orthoesters, spirocyclic orthoesters and ketal lactones. The reaction mechanism is mainly anionic and free-radical ring-opening polymerization. Mix the spirocyclic orthocarbonate EASO containing epoxy ring with epoxy resin and curing agent in a certain proportion.After curing, it is found that the tensile strength gradually increases with the increase of the content of the expanding monomer; the amount of the expanding monomer reaches the total amount of the adhesive At 20%, the tensile strength is at its maximum value, which is 1.86 times that of pure epoxy resin. Continue to increase the amount of expanded monomer. Due to excessive volume expansion, internal stress is generated, but the tensile strength decreases. Huan Jinying et al. synthesized a new spirocyclic orthocarbonate expansion monomer, modified epoxy and found that the glass transition temperature Tg of epoxy resin decreased, and the heat resistance also decreased, but the decrease was not large, but the pull The tensile strength and shear strength increased from 373MPa and 13.4Mp to 450MPa19,9MP4 respectively.
Inorganic filler modified epoxy
The rigid inorganic filler is used to modify the epoxy, because the rigid particles can effectively inhibit crack propagation and absorb part of the energy at the same time, thereby playing a toughening role. The size of the inorganic filler must be appropriate, too small is easy to form stress concentration: too large is equivalent to a two-phase structure, and it is not conducive to toughening; at the same time, it must have an appropriate elastic modulus. The rigid particles are "cold-drawn plastic deformation"; they must also be It has good interface performance with resin. Various inorganic fillers are added to the epoxy resin curing system for modification.Inorganic fillers can be added to the epoxy infusion glue to reduce the size shrinkage of the curing process, improve the thermal conductivity, flame retardancy, adjust the viscosity of the glue, improve or improve the mechanical properties And dielectric properties reduce costs. The filler is refined (1-20m) and surface-treated, and it also has a good toughening effect after being filled with epoxy. Several scientists in the United States use a diameter of 8.0m,
After epoxy resin filled with 6.84m three kinds of carbon fiber, the tensile strength were 3103MPa, 3587MPa and 347MPa respectively. In addition, there are technologies for modifying epoxy with metal salts.