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Grafting maleic anhydride
Mar 17, 2017

In fact is a kind of formula, is the choice of a maleic anhydride monomer, at suitable temperatures and some of the material is grafted. Monomers are acrylic and so forth.

Polyolefin grafted with maleic anhydride by many methods, including solution methods, melting method, such as radiation and solid. But the most important method is to melt method, known as "reactive extrusion", the mechanism of melt grafting is complex, and accompanied by severe side effects, characterized by grafting of polyethylene crosslinked, degradation of polypropylene, as well as two side effects of ethylene-propylene rubber appears. Addition of n, p, s Atom electron donor compounds such as dimethyl formamide (DMF), dimethyl acetamide (DMAC) inhibits Crosslinking and degradation reactions.

Melt-grafting in single screw extruder, twin screw extruder or a Brabender rheometer. Polyolefin, MAH monomer, initiator and other additives, with the help of a small amount of dispersants mixing, then adds the mixture to melt the extruder hopper. Many factors influence the polyolefin graft maleic anhydride, there are variety and concentration of the initiator, monomer concentration, additives and concentrations, temperature and reaction time. Raised agent DCP concentration increased, received branch rate corresponding improve, but DCP dosage too much, with has make joint reaction; DCP fixed not variable Shi, received branch rate with MAH dosage of increased and is rose trend, but continues to increased MAH of dosage Shi docking branch rate of effect variable small; reaction temperature low Shi, DCP of decomposition concentration high, but also conducive to side of occurred, thus consumption has free base, makes free base no obviously improve; melting reaction time (that extrusion machine screw rod of speed) docking branch rate effect is big. When screw rotation speed is too fast, the material stays in the barrel for a short time, inadequate reaction, graft rate. When screw rotation speed is too slow, the shear force is too small, resulting in uneven dispersion of the initiator, and the residence time is too long, can cause serious Crosslinking and grafting. These results in LDPE by grafting process, DCP dosage for 0.08~0.1, MAH-4~5, 160~170℃ of reaction temperature, screw speed 40~45r/min. PP graft during DCP dosage for 0.2~0.4, MAH-5~7, the reaction temperature is 175~180℃, screw speed 30~45r/min is better.