Synthesis and Properties of Phthalonitrile Polymer with a Novel Piperazine Structural Curing Agent

摘要

A novel autocatalytic phthalonitrile (PN) monomer containing piperazine structure, namely 4-[1-(4-aminophenyl)-4-(4-phenyl)piperazine-oxy]phthalonitrile (APPN), is synthesized from the nucleophilic substitution reaction of 1-(4-Aminophenyl)-4-(4-hydroxyphenyl)piperazine and 4-nitrophthalonitrile. The structure of the APPN monomer is characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. The novel 4-nitrophthalonitrile end-capped compound APPN is firstly used to promote the curing reaction of PN monomer 1,3-bis(3,4-dicyanophenoxy)benzene (m-BDB). Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA) showed that the PN resin in the presence of 10 % of APPN possessed outstanding thermal and thermo-oxidative stabilities as well as good mechanical properties, better than the properties of those with 20 % of APPN and 10 % of APPH. Its glass transition temperature (T-g) is higher than 400 degrees C, and the polymer loses 5 % of its weight (T-5%) at 524 degrees C and shows a storage modulus of 1373 MPa at 400 degrees C.