Structure,Properties And Composites Of Poly(Arylene Ether Nitriles) With Pendant Propenyl Groups

Poly(arylene ether nitriles)(PEN), as a novel class of special polymer materials, due to the special structure of the molecules, possesses excellent heat resistance, flame resistance, chemical resistance, high mechanical strength, etc.. Therefore, PEN can be the matrix resin of structural and functional materials and has broad application prospects in the field of aerospace, electronic and electrical equipment, industrial machinery, etc.. Through copolymerization modification, 2,2’-Diallylbisphenol A(DBA) was introduced into the molecular structure to obtain a novel crosslinkable PEN. In addition, the structure and properties, crosslinking reaction and compounding applications were studied.1. A series of PEN homopolymer and copolymers containing propenyl were synthesized via nucleophilic substitution polycondensation from 2,6-dichlorobenzonitrile with 2,2’-Diallylbisphenol A and biphenol, bisphenol A, resorcinol, double valerate, 4,4-bis(4-hydroxyphenyl)valeric acid and phenolphthalein. By means of infrared spectroscopy(FTIR) and proton nuclear magnetic resonance spectroscopy(1H NMR), the polymer structure was proved to be as expected: allyl groups rearranged into propenyl groups. Homopolymer has low molecular weight and poor performance. By introducing other bisphenols, copolymers’ molecular weight increased significantly, the glass transition temperature(Tg=140-186 ℃), thermal stability, thermal oxidative stability and mechanical tensile strength(80-87 MPa) were also enhanced. These PEN all exhibited good solubility in common organic solvents. By comparison, PEN copolymer from 2,2’-Diallylbisphenol A and biphenol obtained optimal performance.2. To explore the effect of 2,2’-Diallylbisphenol A content on the performance of PEN, a series of poly(arylene ether nitriles) containing side propenyl groups(DPEN) were synthesized from 2,6-dichlorobenzonitrile with 2,2’-Diallylbisphenol A and biphenol. By means of FTIR, the DPEN structure was proved to be as expected. With the increase of DBA contents, molecular weight gradually decreased; Tg(207-169 ℃), thermal stability(Td5%=511-423 ℃) and mechanical tensile strength(105-79 MPa) showed a downward trend, but still maintained a higher combination property; the solubility of DPEN was improved obviously. By comprehensive comparison, DPEN-20 which DBA content is 20% is the optimal selection for the subsequent study of propenyl.3. Through different propenyl contents, processing time and processing temperature under heat treatment, the influence of double bond crosslinking reaction on the structure and properties of DPEN copolymers was investigated. It’s found that only double bond is involved in the crosslinking reaction during the heat treatment by DSC and FTIR analysis. The test results also showed that with the increase of heat treatment temperature, Tg increased obviously, the tensile strength increased first and then decreased, the dielectric constant decreased and the complex viscosity increased gradually. In all, double bond crosslinking reaction is an effective way to improve the properties of PEN.4. Zinc oxide(Zn O)/multi-walled carbon nanotubes(MWCNTs)/ DPEN-20 micronanocomposite material films were fabricated by uncomplicated and accessible method. SEM revealed that MWCNTs were isolated by Zn O and realized better dispersion in matrix. Zn O particles hindered conductive MWCNTs from bridging with each other, working as dielectric obstacle. The polymer film’s Tg was more than 200 ℃, and 5% weight loss temperature was greater than 430 ℃, which showed good dimensional stability and thermal stability. With the increase of inorganic filler contents, the tensile strength of the composite increased first and then decreased, but it is maintained in a good toughness(>90 MPa). The dielectric constant increased to 45(100 Hz), which is 15 times higher than that of pure PEN, with 6 wt% MWCNTs loading.