Chemical modification
Chemical modification of ethylene-propylene rubber When peroxide or sulfide is added to ethylene-propylene rubber, when peroxide is used as curing agent, the elastomer and plasticizing phase will be affected to varying degrees. Peroxide attacks the elastomer and polymer. , generating active groups, resulting in more effective cross-linking, resulting in the entanglement of molecular segments, and the larger the entanglement, the greater the shrinkage. However, the amount of peroxide must be strictly controlled. Excessive amount will make cross-linking difficult and the overall impact strength will decrease.
Grafting reaction of EPDM Since EPDM does not contain polar groups, it has poor compatibility with polar polymers. Dibutyl maleate with high boiling point and low toxicity is used for fusion bonding. branched into its hydrocarbon chain with polar groups to obtain functionalized polymers, which improved its compatibility with polymers containing polar groups, such as in melt blending with nylon for melt grafting. In EPDM, the carboxyl group or anhydride group inserted in the active chain of EPDM reacts with the end group component of nylon to improve the bonding force.
Grafting reaction
Grafted Maleic Anhydride Maleic anhydride grafted hydrogenated copolymers were used as compatibilizers for the melt-mixed phase. Maleic anhydride was introduced into the polyolefin main body by melt grafting as an interfacial compatibilizer. The higher the grafting amount of maleic anhydride, the higher the mechanical properties of the blends.
Diethylhexyl fumarate is used for grafting fumarate. In the molten state, the free radical reaction initiated by peroxide can graft the monomer of fumarate on the polymer to improve the blend. Medium sphere size. The grafted hydroxyethyl methacrylate uses peroxide as the initiator, and the polymer is grafted with hydroxyethyl methacrylate in the molten state, but the amount of peroxide should be controlled.
Grafted glycidyl methacrylate The epoxy group in glycidyl methacrylate (GMA) has high reactivity, and the product obtained by grafting the polymer can be used as an excellent compatibilizer for polymer alloy systems. The polymer, glycidyl methacrylate and dicumyl peroxide are uniformly mixed in advance, and then granulated and grafted by melt extrusion. The grafting rate did not increase with the increase of peroxide, but decreased with the increase of peroxide. In the grafting reaction, the added styrene-based macromolecular free radicals have higher reactivity with the polymer than GMA. Styrene was preferentially grafted onto the polymer to form more stable styrene-based macromolecular radicals, and then GMA participated in the reaction. The reaction rate of GMA with styrene-based macromolecular free radicals is much higher than that of GMA and polymers, so the grafting rate of GMA can be increased, a large amount of free radicals of polymers are consumed, and the degradation of polymers can be inhibited. Adding a small amount of unsaturated double bond thermoplastic elastomer (SEBS) in the molecule or linoleic acid triglyceride with more double bond in the molecule can also reduce the degradation.
The non-melting grafting method reacts the polymer with chlorobenzene, tert-butyl peroxide chlorinated solution, maleic anhydride and acetone, and the reactant is washed with a large amount of acetone, filtered and dried to obtain the graft of maleic anhydride.
Micro-oxidized polymer powder for grafting acrylic acid is reacted with acrylic acid to prepare polyacrylic acid grafted polymer. When this polymer and kaolin composite material are used as compatibilizer, the mechanical properties of the composite are effectively improved, and toluene is used as the compatibilizer. When the solvent is used, the graft ratio of the obtained polymer grafted by methacrylic acid can reach 20%. Radiation grafting uses CO60 radiation grafting source to graft acrylonitrile onto the polymer, and the grafting rate can reach more than 40% by using a suitable solvent.