Study on curing reaction of 4-aminophenoxyphthalonitrile/bisphthalonitrile

A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile(APN) and 4,4'-bis(3,4- dicyanophenoxy)biphenyl(BPH) by directly powder-mixing and copolymerization.Differential scanning calorimeter(DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends,and the results indicated that the introduction of APN accelerated the curing rate of BPH,and the existence of BPH decreased the curing temperature of APN/BPH systems.The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis(TGA),and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.

Design and Properties of Fluoroelastomer Composites via Incorporation of MWCNTs with Varied Modification

Multi-walled carbon nanotubes(MWCNTs)modified with silane coupling agent A-1120(MWCNTs-A1120)were prepared.Compared with the raw MWCNTs,acidified MWCNTs(MWCNTs-COOH),and MWCNTs grafted with EDA(MWCNTs-NH2),MWCNTs-A1120 have the best dispersion in fluoroelastomer at the same doping ratio.Therefore,fluoroelastomer/MWCNTs-A1120 composite has the best mechanical properties with tensile strength of 13.92 MPa and elongation at break of 111.78%.Then,the effects of doping amount of MWCNTs-A1120 on the electrical properties of the composites were investigated.The dielectric constant of the composite increases with the increase of MWCNTs-A1120,and the dielectric loss does not change much at the low doping amount such as 0.5 wt%.When the doping amount of MWCNTs-A1120 is 5 wt%,the dielectric constant and the dielectric loss value are greatly increased,and the volume resistivity is greatly decreased,which proves that the conductive network is formed in the composite,so the filling amount of 5 wt%is the percolation threshold.The tensile deformation of the sample also affects the electrical properties of the composites.As the tensile deformation increases,the dielectric constant and dielectric loss of the composite decrease.For the composite with 5 wt%MWCNTs-A1120,excessive tensile deformation will destroy the conductive network structure of the composite,so the composite will change from conductive material to dielectric material.Therefore,such composite is a good candidate for flexible conductive material or flexible dielectric material used in harsh environments such as high temperatures and various aggressive solvents.

Polyarylene Ether Nitrile and Titanium Dioxide Hybrids as Thermal Resistant Dielectrics

With the expanding application of capacitors,thermal resistant dielectric materials are in high demand due to the increasing harsh environments where the capacitors are needed and the heat generated by the capacitors.Herein,we present polyarylene ether nitrile and titanium dioxide hybrids which can be used as thermal resistant dielectrics for these capacitors.Phthalonitrile modified titanium dioxide(TiO_(2)-CN)and phthalonitrile end-capped polyarylene ether nitrile(PEN-Ph)are firstly prepared.After being cast into TiO_(2)-CN/PEN nanocomposite films,these composites self-crosslink upon heating at 320℃for 4 h,forming the polyarylene ether nitrile and titanium dioxide hybrids(TiO_(2)-PEN).Improved dielectric constants which are stable from room temperature to 200℃of these hybrids are observed,indicating the potential application of the hybrids as thermal resistant dielectrics.