The Study Of Nano Polystyrene Sphere/LDPE Dielectric Composites

PS/LDPE nanocomposites were prepared by melt blending method,the specimen obtained by vulcanizing machine were characterized by scanning electron microscopy firstly.Through the comparative analysis of DSC Experiment on pure LDPE and PS/LDPE nanocomposites,it can be seen that the crystallinity of the composites with PS nanoparticles is higher than that of pure LDPE.Compared with pure LDPE,the storage modulus and loss modulus of PS/LDPE were slightly higher and the peak value of damping loss decreased slightly and moved to the high temperature.Secondly,in order to study the effect of the mass fraction of nano particles on the dielectric properties of PS/LDPE,nanocomposites with mass fractions of PS 0%,0.5%,1% and 2%,respectively,were prepared.The results show that the conductivity of the samples increases as the temperature increases.The electrical conductivity of the nanocomposites was much smaller than that of pure LDPE at low temperature,and the conductivity of the composites decreased slightly with the increase of the filler concentration.The space charge experiments show that space charge inhibition ability was enhanced by the addition of PS fillers.With the increase of doping,space charge inhibition ability gradually improved,and experimental results show that the PS/LDPE nano composite with 2% PS showed the best space charge inhibition effect.Thermally stimulated current(TSC)spectrum showed that PS nanoparticles changed the trap depth and density,and the trap level were significantly different from that of the pure LDPE,affectting the LDPE space charge accumulation and DC conductivity.The DC break down strength results show that the breakdown strength of PS/LDPE nanocomposites is lower than that of pure LDPE,which may be due to the shallow trap caused by the increase of shallow carrier trap states under high electric field.On the one hand,the addition of nanoparticles increases the density of shallow traps;on the other hand,it increases the density of impurities.With the increase of DC electric field strength,more electrons will be excited and more positive and negative ions would be produced,leadings to thedecrease of the breakdown field.Through the measurement of dielectric spectrum,it is found that the dielectric constant of PS/LDPE nanocomposites is slightly higher than that of pure LDPE.It is shown that the mechanism of the space charge inhibition of the nanocomposites formed by the addition of PS nanospheres is different from the nanocomposites formed by the addition of MgO nanoparticles.In the case,the MgO nanoparticles formed a polarized electric dipole trap due to the high dielectric constant,which played an important role in reducing the conductivity and suppressing the space charge.At the same time,the energy structure and local density distribution theory of interface structure of PS nano particles and LDPE matrix analysis,confirmed that the addition of PS nanoparticles brings in both electron traps and hole traps,and their depth and density are different.Through a series of experimental exploration and theoretical analysis,some research results have been obtained.It is believed that it has significance and value for the research and development of nanocomposite insulating materials.