Syntheses And Properties Of Novel High Temperature Phthalonitrile Resins

Polyphthalonitrile reisn, a kind of novel high temperature polymer which can be initiatedwith many types of curing additives such as transition metals or organic amines, andaddition polymerization occurred during reaction through nitrile groups. Polyphthalonitrileresin have good processability, excellent thermal and thermo-oxidative properties(Td,5%>500℃), high storage modulus (E’>3GPa), high glass transition temperature(Tg>350℃) and good water uptake properties (<3%), which could be used as structuralmaterials, coating and adhesive for applications in aerospace, submarine, electronic packing,mechanic industries and chemical industries.In this research, develop novel kind of phthalonitrile resin is the main topic. Firstly, twokinds of phthalonitrile monomers based on [1,3,5]-triazine structure have been synthesized.The chemical structure of the phthalonitrile monomers was characterized by Fouriertransform infrared spectroscopy (FI-IR) and nuclear magnetic resonance spectroscopy (1Hand13C NMR). Curing behavior of the phthalonitrile monomers with4,4’-diaminodiphenylether (ODA) were recorded by differential scanning calorimetric (DSC).Thermogravimetric analysis (TGA) revealed that both the two kinds of triazine-basedphthalonitrile polymers possessed outstanding thermal stabilities. Thermal decompositionkinetic analysis indicated that the energy of activation (Ea) of the triazine structure basedphthalonitrile polymers are205.6and152.3kJ/mol respectively. Dynamic mechanicalanalysis (DMA) showed that the storage moduli (E’) are3.62GPa and3.66GParespectively, and glass transition temperatures (Tg) are higher than400℃. Postcuringeffects were investigated and it showed that more excellent thermal and mechanicalproperties were achieved with postcuring.Secondly, a novel kind of alky center-trisphenolic based phthalonitriel,1,1,1-tris-[4-(3,4-dicyano phenoxy)phenyl]ethane (TDPE), was synthesized from1,1,1-tris-(4-hydroxyphenyl)ethane (THPE) via a facile nucleophilic displacement of anitro-substituent from4-nitrophthalonitrile (NPN). The structure of TDPE monomer wascharacterized by FT-IR,1H and13C NMR spectra. Curing behavior of TDPE with4-(aminophenoxy)phthalonitrile (APPH) were recorded by differential scanningcalorimetric (DSC) and it showed a large processing window (122℃) which is favorable toprocessing TDPE polymers. The structure of TDPE polymer was discussed and the thermalstabilities of TDPE polymer were evaluated by thermogravimetric analysis (TGA). TheTDPE polymer exhibited excellent thermal stability, and mechanism of thermaldecompositions were explored. The TDPE polymer showed high storage modulus and highTg(>380℃) as revealed by dynamic mechanical analysis (DMA), and the water uptake was less than3%after480hours immersion in water.Thirdly,4-aminophenoxy phthalonitrile (APPH) has been synthesized and utilized tocatalyze the curing of resorcinol-based phthalonitrile monomer,1,3-bis(3,4-dicyanophenoxy)benzene (BDB), and bisphenol-A-based phthalonitrile monomer,2,2-bis[4-(3,4-dicyanophenoxy)pheny] propane (BDPP). Fourier transform infrared spectroscopy(FT-IR) showed that polytriazine structures have been formed during polymerization, andthe introduction of APPH facilitated curing reaction. The prepared BDB and BDPP resinsshow outstanding thermal stability, high modulus and high glass transition temperature (Tg)which were further improved with increase in APPH content (5wt%,10wt%,20wt%).Thermal decomposition kinetics of phthalonitrile resins have been investigated throughthermogravimetric experiments using Friedman method and Flynn-Wall method, andthermal parameters were calculated, and mechanisms of thermal decomposition and hightemperature properties have been investigated. Postcuring effects on thermal and dynamicmechanical properties were evaluated using thermogravimetric analysis (TGA) anddynamic mechanical analysis (DMA).