Modification method of PP material
1, PP material modification method - filling modification
Filling modification generally refers to the addition of calcium carbonate, talcum powder, mica powder, wollastonite powder and other non-metallic mineral powder materials or other materials in PP resin, not only can significantly improve the rigidity, heat resistance, dimensional stability, high temperature creep resistance, hardness and so on, most can also play the role of incremental cost reduction. In the process of filling modification, the problem of uniform distribution and dispersion of filler in PP resin matrix should be solved first. The unique needle-like structure of wollastonite in inorganic fillers can solve this problem well. In addition, wollastonite needle-like fiber can also obviously achieve the effect of enhancement and modification.
2, PP material modification method - copolymerization modification
Copolymerization modification refers to the modification of propylene monomer in the polymerization stage by using catalyst. The copolymerization of propylene monomers with other olefin monomers can improve the low temperature toughness, impact property, transparency and processing fluidity of PP materials. For example, in the copolymerization of propylene and ethylene, the crystallinity of the polymer is reduced due to the irregular distribution of ethylene and propylene chain segments. Ethyl-propylene copolymer rubber can be prepared by block copolymerization of 2%-3% ethylene monomer, which can withstand low temperature shock of -30¡æ.
3. Modification method of PP material -- blending modification
Blend modification is to blend other plastics, rubber or thermoplastic elastomer with PP material to prepare polymer alloy with these polymer properties. The blending modification of PP can improve the low temperature impact resistance, transparency, coloring and antistatic properties of the polymer. Polymer commonly used in PP blending modification are PE, EPR, EPDM, ER, SBS, EVA and so on. After EPDM, SBS, EVA and other elastomers are blended with PP, the elastomer particles in the material can absorb part of the impact energy, and act as a stress concentrator to induce and inhibit the crack growth, so that PP is transformed from brittle fracture to ductile fracture, so that its impact strength is greatly improved, and the toughness of PP material is effectively improved.
4, PP material modification method - crosslinking modification
The crosslinking modification of PP is an effective method to improve the thermal deformation temperature of PP and also improve the mechanical properties of PP. The crosslinking modification mainly includes radiation crosslinking and chemical crosslinking. Radiative crosslinking is a reaction in which PP molecular chain produces free radicals under the action of high-energy rays. Chemical crosslinking is generally achieved by adding peroxide as initiator and assistant crosslinking agent to PP.