Study On Reactive Extrusion Polyethylene Grafted Maleic Acid Monoester

In order to achieve the higher requirements,many researchers have carried out the modification of polyolefin.The common modification method is polar monomer(maleic anhydride)grafting PE or PP,used to prepare adhesive resin or compatibility agent.However,MAHhas a low melt point and a low boiling point,what's more,it sublimates easily at 60~80~oC.So it is difficult to get a high grafting degree,which leads to a large amount of residual MAHand pollution in production and application.In this paper,to improve the system of MAH grafted PE,and achieve more excellent industrial production,raw materials and processing technology of LLDPE grafted the maleic acid monoester were studied.On the one hand,the alkyl chain of maleic acid monoester can improve the interfacial compatibility between the polyethylene and monomer,and it can increasethe grafting degree of maleic acid monoester.On the other hand,the polar groups in maleic acid monoester can be chemically bonded with metal surface,whichprovides the bonding strength between the modified polyethylene and polar materials.In this paper,C8 was synthesizedas a polar monomer.The reactive extrusion was carried outby the SHJ-20 twin screw extruder.The effects of the weight of the DCP and C8 on the grafted productswere researched.It was found thatDCP reduced the melt flow rate.when the contentof DCP increased in 0~0.1g/100gPE,the grafting degree and peel strength increased,and when the content of DCP was more than0.1g/100gPE,the grafting degree and peel strength decreased.When the content of C8 increased(0~4g/100gPE),grafting degree was increased,however,too much C8wouldmakethe color ofthe product become yellow,decrease themelt index,deteriorate thepeel strength and reduce theutilization of the monomer.The C4,C8,C12 were grafted with LLDPE through reactive extrusion respectively.And compared the properties(such as grafting degree,peel strength,mechanical properties and heat resistance)with MAH grafted polyethylene.Itwasfound that the longer alkyl chain ester had the better interface compatibility between maleic acid monoester and polyethylene,the greater graftingdegree,the better processing performance,and the more excellent bonding properties and heat resistance.Compared with MAH grafted polyethylene in the same condition,the results showed that the grafting degree of LLDPE-g-C4 increased 14.8%~32.03%,and peel strength increased 4.7%~46.43%;the grafting degree of LLDPE-g-C8increased 71.62%~89.03%,peel strength increased 32.94%~89.28%.At the same time,the grafting degree of LLDPE-g-C12 increased 195.11%~283.59%,peel strength increased 45.88%~110.70%.TheC8 and CF8 were grafted with LLDPE through reactive extrusion respectively.Compared the melt index and grafting degree of the grafted sample,it was found that isomerization of maleic acid monoester has little effect on the grafting degree and melt index.The C8 and CY8 were grafted with LLDPE through reactive extrusion respectively.Compared the melt index and grafting degree of the grafted sample,it was found that the branched chain in the alkyl chain of maleic acid monoester increased the graft degree but reduced the melt flow rate.The grafting degree,melt index and mechanical properties of the grafted samples were studied by using the composite polyethylene as matrix resin.It was found that adding HDPE enhanced the strength of the grafted products and adjusted the melt flow,but reduced the grafting degree.