Preparation And Thermal Conductivity Of Poly (Vinylidene Fluoride) Composite

Due to the growing needs of thermal management in modern electronics,high thermal conductive insulation polymer composites are increasingly demanded.The high level of thermal conductive filler is often required in high thermal conductivity composite materials.However,the high level of filler can lead to three questions,one of which is deterioration on the mechanical properties of the substrate material;The second is that the processing flow performance is reduce;Third,it is to cause the cost of materials to rise dramatically.In this dissertation,the research about how to prepare high thermal conductivity low adding amount of composite materials issue matrix with poly(vinylidene fluoride)(PVDF),it is a kind of thermoplastic polymer insulation materials,and is widely used.There are two kinds of fillers.One is boron nitride nanosheet(BNNS),which is called “white grapheme” with high thermal conductivity and electrical insulation,so BNNS can be widely applied in the field of thermal insulation.The other one is graphdiyne(GDY).It is a new two-dimensional full carbon nanomaterial after zero-dimensional fullerenes,one-dimensional carbon nanotubes and two-dimensional graphene.It is known as the most stable synthetic of diyne carbon allotropes.GDY is a semiconductor,and its special electrical propertie has attracted a large number of researchers.However,there is little report about thermal conductive property of GDY.In this dissertation,BNNS and GDY as thermal conductive filler with low amount have been investigated.It indicates that BNNS and GDY have wide development prospects in the field of thermal conductivity and insulation.(1)Boron nitride nanosheet(BNNS)was prepared through molten hydroxide assisted liquid exfoliation of hexagonal boron nitride(h-BN)powder and used as thermally conductive filler.The poly(vinylidene fluoride)(PVDF)/BNNS films were obtained through solution blend and hot pressing.With only 4 wt% BNNS,the in-plane thermal conductivity of PVDF/BNNS composite achieved 4.69 W/mK,with a thermal conductivity enhancement of 2297 % compared to neat PVDF.However,the through-plane thermal conductivity of the composites is only 0.23 W/m K,which shows a high thermal conductive anisotropy over 20.The thermal conductive anisotropy and the high in-plane thermal conductivity can be attributed to the formation of thermally conductive network in PVDF matrix.Thus,the BNNS reinforced PVDF films are promising for use as an efficient heat spreader for electronic cooling applications.(2)Graphdiyne(GDY)was used as thermally conductive filler.The poly(vinylidene fluoride)(PVDF)/BNNS films were obtained through solution blend method and hot pressing.With only 1 wt% GDY,the in-plane thermal conductivity of PVDF/GDY composite achieved 3.88 W/mK,with a thermal conductivity enhancement of 2260 % compared to neat PVDF.However,the through-plane thermal conductivity of the composites is only 0.184 W/mK,which shows a high thermal conductive anisotropy over 21.The thermal conductive anisotropy and the high in-plane thermal conductivity can be attributed to the formation of thermally conductive network in PVDF matrix.Thus,GDY can be an ideal filler for the preparation of high thermal conductivity PVDF-based heat spreader.