Research Of NanoAl₂O₃（AIN）/Ldpe Composites Dielectric Properties

Nano-inorganic particles has a range of extraodinary properties different from conventional materials. When adding a certain amount of nano-inorganic particles to the polymer matrix,the composite not only keeps the stable physicochemical charactetistic of polymer but also possesses of nano particles properties.In order to improve the electrical properties of polymer and more complete performance in the electrical equipment and microelectronic products, LDPE as a matrix in this research,then adding different content of nano-particles A12O3/AlN to it. The composites with various nano-particles contents are prepared by melt blending method.Then prepared a series of test samples of different thermal history to measure.In order to understand the effect of adding nanoparticles on dielectric properties of polymer matrix, the samples are measured by Scanning Electron Microscope(SEM) to characterize of dispersion of nanoparticles in polymer matrix, then crystallization and thermal properties of different contents of nanoparticles composites under different thermal history conditions were characterized by Differential Scanning Calorimetry(DSC) and X-ray diffraction (XRD), moreover, dielectric constant, dielectric loss, volume resistivity and breakdown strength of composites were measured correspondingly.The results show that:nanoparticles can be uniformly dispersed in nano-scale polymer matrix. Nanoparticles added to the LDPE played the role of heterogeneous nuclear agents, increase the crystallinity of LDPE and increase with the inorganic particles contents. Melting temperature of the composites are increased along with the increase of nanoparticles contents shows that thermal properties will get better.The results of test about dielectric properties of materials show that dielectric constant,breakdown strength,volume resistivity also increase along with contents of filler, however the dielectric loss of materials has no significant changes.Composites under different thermal history conditions has different crystallinity. Composites cooling too fast by ice water quenching lead to imcomplete crystallization, therefore the crystallinity of quenching is less than slow cooling. Moreover, dielectric properties such as dielectric constant,volume resistivity, breakdown strength and thermal stability are also reduce correspondingly.