Control Of Polyethylene Foaming Performance

Polyethylene,as the largest production of synthetic resins,has good electrical insulation,heat insulation and other properties,excellent toughness,flexibility and cushioning properties.It is currently used in many fields such as packaging,chemicals and construction widely.PE foaming material has large output and cheap price.It can give more new properties to meet the needs of modern industry on the existing excellent performance.It can replace other expensive and difficult to produce foaming materials.For polyethylene,pure CO2 foaming has become a hot topic in recent years.The polyethylene's ability to adsorb CO2 is far inferior to the ability to adsorb alkanes.In the foaming of CO2,PE shrinks severely.The expansion ratio is low,and the cell size and cell morphology are far inferior to alkane foaming.This paper's research on PE foaming covers three kinds of density polyethylene.First,the chain extension effect of NEXAMITE M480502 on LLDPE 7042,HDPE 6098,and HDPE 7000F was studied.Second,HDPE 6098 and HDPE 7000F are compared.The rheological crystallization properties of two high-density polyethylenes are finally melt-blended to blend LDPE 18D with the other three polyethylenes to investigate the factors affecting their foaming properties.The effect of the addition of chain extender on the thermal and rheological properties of polyethylene was studied by the compaction torque curve,differential scanning calorimetry and dynamic rheological test.Combined with batch foaming experiments,the improvement of foaming properties of chain extenders was studied.The results show that the addition of chain extender can increase the molecular weight of LLDPE 7042,increase the degree of branching,improve the rheological crystallization performance,and the cell morphology is regular and dense.It also increases the complex viscosity to the other two polyethylenes,but it limits the growth of cells.The difference in rheological properties of the two high-density polyethylenes is the main reason for the differences between the two in the full text.Appropriate crystallization rate and melt viscosity are the keys to polyethylene foaming.The results show that HDPE 6098 has a faster crystallization rate and suitable melt strength.The maximum expansion ratio of the sample reached 17.69 times,the cell density was 1.30×106 cells/cm3,and the appropriate foaming temperature was 132?139?,and no shrinkage occurred.In order to further improve the problems of small polyethylene adsorption and sample shrinkage,the rheological properties of the blending system were adjusted by melt blending with other polyethylenes.The results show that after adding 40%HDPE 7000F,the expansion ratio is the largest,reaching 12.19 times,the cell density is two orders of magnitude greater than that without addition,and the sample does not shrink and the surface is smooth.