Study On Rare Earth Complexes/Polyethylene High Performance Materials

Linear low density polyethylene(LLDPE)was considered as one of the options for the development of environmentally friendly insulating materials because of its moderate melting point and good electrical insulation performance.As a new type of materials,rare earth coordination polymers had attracted wide attention.In this paper,LLDPE was selected as the matrix to prepare high performance electrical insulation materials,and different methods were used to improve the properties of materials.Firstly,LLDPE was introduced into the active site by pre-irradiation technology.The prepared voltage stabilizer 4-acryloxyacetophenone(AAP)with active double bonds was grafted onto the main chain of LLDPE by melt grafting method.The effect of precipitation on the properties of the samples was studied and compared with the ungrafted samples.The breakdown strength of LLDPE-g-AAP decreased less than that of LLDPE/AAP through accelerated precipitation experiment at 60 ~oC.It showed that the electrical breakdown strength of LLDPE can be maintained at a high level for a long time by grafting reaction.The thermal stability of the material was proved by DSC and the processing performance of the material was proved by rheological test.Then,poly(styrene-copoly-4-acryloxybenzoic acid)(P(St-co-ABA)was prepared by copolymerization.P(St-co-ABA)was added to LLDPE by melt blending,and LLDPE-g-PS was used to increase the compatibility of the system.The electrical insulation properties,thermal properties and surface morphology of LLDPE/LLDPE-g-PS/P(St-co-ABA)blends were studied.The results showed that the addition of P(St-co-ABA)and LLDPE-g-PS had no effect on the melting temperature,crystallization temperature and crystalline form of the samples,but increased the crystallinity.The results of SEM showed that the compatibility of the blends was improved effectively by adding LLDPE-g-PS as compatibilizer.The electrical insulation properties of the blends showed that the breakdown strength of LLDPE was greatly improved by adding P(St-co-ABA).When the content of P(St-co-ABA)was 1.0 g,the breakdown strength increased to 333.8 kV/mm,and the space charge accumulation effect was the best.The mean volume density was 1.35 C/cm~3 and 1.35 C/cm~3 in 30 s and 1800 s,respectively.The dielectric constant was improved,but the dielectric loss was not affected within a certain range.Finally,the effect of rare earth complexes on the properties of LLDPE was discussed.Three rare earth complexes were synthesized by using P(St-co-ABA)as ligand,1,10-phenanthroline(Phen)as co-ligand,rare earth ions Nd(Nd),Eu(Eu),Tb(Tb)as central ions.FTIR characterization showed that the three complexes were synthesized successfully.LLDPE/LLDPE-g-PS/P(St-co-ABA)-Nd(?),LLDPE/LLDPE-g-PS/P(St-co-ABA)-Eu(?),LLDPE/LLDPE-g-PS/P(St-co-ABA)-Tb(?)were prepared by adding three rare earth complexes to LLDPE.DSC results showed that the addition of three rare earth complexes had little effect on the thermal properties of LLDPE.EDS results showed that the three rare earth ions were dispersed well in LLDPE matrix.From the results of electrical insulation properties,the breakdown strength of the three rare earth complexes blends have been improved to different degrees.Among them,the Europium rare earth complexes blends increased the most,which was 324.8 kV/mm.The space charge accumulation effect was the best.The mean volume density was 1.21 C/cm~3 and 1.37 C/cm~3 in 30 s and 1800 s,respectively.The dielectric constant was improved,but the dielectric loss was not affected in a certain range.