Chemical Modification of Polypropylene PP Particles
Chemical Modification of Polypropylene PP Particles Through copolymerization modification, crosslinking modification, grafting modification, adding nucleating agent, etc., the polypropylene polymer component and macromolecular structure or crystal configuration are changed to improve its mechanical properties, heat resistance, aging resistance and other properties, improve its comprehensive performance, expand its application field.
PP Polypropylene Granuleschemical modification
By copolymerization modification, graft modification, adding nucleating agent, etc., the polypropylene polymer component and macromolecular structure or crystal configuration are changed to improve its mechanical properties, heat resistance, aging resistance and other properties, improve its comprehensive performance, expand its application field.
(1) copolymerization modification
Copolymerization modification is carried out in the stage of propylene monomer synthesis using catalysts such as metallocene. When the monomer is polymerized, the added olefin monomer is copolymerized with it to obtain random copolymers, block copolymers and alternating copolymers, etc., and homopolymerization.PP Polypropylene GranulesThe mechanical properties, transparency and processing fluidity are all improved. The complex formed by the metallocene catalyst is a transition state with irregular shape limited to a certain extent as a single active center to achieve precise control of relative molecular mass and its distribution, comonomer content, distribution on the main chain and polymer crystal structure.
(2) graft modification
PP Polypropylene GranulesResin molecules are non-polar crystalline linear structure, low surface activity, non-polar. There are defects of poor surface printing, poor coating adhesion, difficult to blend with polar polymers, and difficult to be compatible with polar reinforcing fibers and fillers. Graft modification is the introduction of polar groups to its macromolecular chain to achieve improvedPP Polypropylene GranulesBlending, compatibility and adhesion, to overcome the shortcomings of difficult blending, difficult compatibility and difficult bonding. Under the action of the initiator, the grafting monomer undergoes grafting reaction during melting and mixing. The initiator decomposes to produce active free radicals when heated and melted. When the active free radicals meet the unsaturated carboxylic acid monomer, the unstable bond of the unsaturated carboxylic acid monomer is openedPP Polypropylene GranulesReactive radicals react to form graft radicals, which are subsequently terminated by molecular chain transfer reactions.PP Polypropylene GranulesCommon graft modification methods are: melting method, solution method, solid phase method, suspension method, etc. after graft modificationPP Polypropylene GranulesThe hydrogen atoms in the molecular chain are replaced with strong polarity, and these polar groups makePP Polypropylene GranulesCompatibility is enhanced, heat resistance and mechanical properties are greatly improved.
(3) crosslinking modification
It is mainly a linear or branched polymer modified by crosslinking method to become a polymer with a network structure. The mechanical properties, heat resistance and morphological stability of polypropylene PP particles can be improved by crosslinking modification, and the molding cycle can be shortened. The main methods of cross-linking modification of polypropylene are chemical cross-linking modification and radiation cross-linking modification. The main difference between them is that the cross-linking mechanism is different and the active source is different. Chemical cross-linking modification is realized by adding cross-linking additives to polypropylene modification. Radiation cross-linking modification is mainly realized by strong radiation or strong light.PP Polypropylene GranulesThe thickness requirement makes the law difficult to popularize. At present, the silane graft crosslinking method has developed rapidly because of its ability to prepare materials with excellent performance. The polypropylene PP produced by the silane graft crosslinking method has high strength, good heat resistance, high melt strength, strong chemical stability and good corrosion resistance.