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Novel phthalonitrile resins (BPAPNs) were prepared by blending phthalonitrile-terminated oligomeric polyaryl ether nitrile, 4,4′-(1,3-phenylenebis(oxy))diphthalonitrile (PN), and 4-amino-4-(3,4-dicyanophenoxy)phenyl. The curing behavior of the blends was studied by differential scanning calorimetry, Fourier-transform infrared spectroscopy, and rheology measurements. Additionally, quartz fiber-reinforced composites were prepared by hot-pressing process. Thermal stability and mechanical properties of cured phthalonitrile resins and composites were characterized and discussed. Compared with that of pristine PN, the impact strength of cured BPAPNs increased by 60%, while the thermal properties were not sharply compromised. Additionally, the maximum bending strength of BPAPNs composites reached 855 MPa, which was 56% higher than that of pristine PN. The current method shed light on the toughening of phthalonitrile resins, and the corresponding phthalonitrile resins could be used as the matrix for high-performance composites. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Novel phthalonitrile copoly-oligomers were synthesized by an improved method. • Oligomers exhibited good processability for prepreg and hot-press manufacture. • Glass transition temperatures of cured polymers were higher than 450 °C. • Bending strength reached 942 MPa, capable as structural composite matrices. Abstract A novel series of phthalonitrile terminated fluorene based copoly-oligomers (BPNs) were designed and synthesized by an improved method and could be cured in the presence of bis[4-(4-aminophenoxy)phenyl]sulfone. The structure of oligomers was characterized, while their curing behavior was systematically studied. The oligomers exhibited good solubility, which facilitated the preparation of prepregs. Later quartz fiber reinforced composites were prepared by hot-pressing process, and their thermal and mechanical properties were characterized. The glass transition temperatures of the composites were higher than 450 °C, and the bending strength reached 942 MPa. The combination of excellent thermal and mechanical performance indicated BPNs could be potentially applied in high performance composites or as universal modifiers for heat resistant resins. [ABSTRACT FROM AUTHOR]

A self‐catalyzed fluorinated novolac‐phthalonitrile resin was synthesized by nucleophilic substitution reaction between fluorinated novolac oligomer and 4‐nitrophthalonitrile. Structure of the final product was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. With the introduction of fluorine into the backbone, the fluorinated novolac‐phthalonitrile presented elevated performance. Compared with the analogous novolac‐phthalonitrile resin, the dielectric constant of the cured fluorinated resin decreased from 3.30 to 3.15, and the dielectric loss effectively decreased from 0.012 to 0.004 at the frequency of 1 MHz. Furthermore, the fluorinated novolac‐phthalonitrile resin possessed a broader processing window and higher thermo‐oxidative stability than the analogous novolac‐phthalonitrile resin. Consequently, the fluorinated novolac‐phthalonitrile resin may be a good candidate for matrix of high performance composite in electronic and aerospace industries. [ABSTRACT FROM AUTHOR]

ABSTRACT: A series of phthalonitrile terminated polyaryl ether nitrile oligomers containing fluorene group (BPPENs) were synthesized and cured in the presence of bis[4‐(4‐aminophenoxy)phenyl]sulfone. Additionally, the quartz fiber reinforced composites were prepared by hot‐pressing process. The structure of oligomers was characterized by 1H‐NMR and GPC. The curing behavior of BPPENs was studied by DSC, IR, and rheological tests in detail. Thermal stability and mechanical properties were also investigated. The results showed that the oligomers showed excellent solubility. BPPENs could be dissolved in common solvents at ambient temperature. TGA and DMA results showed that the cured polymer and composites possessed excellent thermal properties with high residual weight of 72.4% at 1000 °C and 5% thermal degradation temperature (T5%) of 548 °C under inert atmosphere. The bending strength of quartz fiber reinforced composites was about 500 MPa, exhibiting good mechanical property. The products could be used as high performance polymers or a modifier for heat‐resistant resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46606. [ABSTRACT FROM AUTHOR]

Soluble hyperbranched poly(arylene ether nitrile)s end-capped by either hydroxyl (HBPAEN-OHs) or phthalonitrile groups (HBPAEN-PNs) were synthesized via nucleophilic substitution reactions, where activated carbon supported calcium oxide was used as the catalyst to avoid crosslinking at high conversion. In order to evaluate their potential application in phthalonitrile resins, these hyperbranched polymers were blended with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-(4-aminophenoxy)phthalonitrile, then cured into polymers. Curing mechanisms of different prepolymers were proposed and compared, and processability, thermal and mechanical properties were characterized. The introduction of HBPAEN-OHs was found to postpone the curing, while thermal and mechanical properties were compromised. On the contrary, the usage of HBPAEN-PNs was beneficial to both processability and thermal properties. More importantly, the impact strength for polymers containing HBPAEN-PN could be as high as 12.92 kJ m−2, indicating such resin could be potentially applied as high temperature structural composite matrices. In addition, the toughening mechanism was proposed and discussed. Image 1 • Novel hyperbranched poly(arylene ether nitrile) modifiers were synthesized. • Phthalonitrile prepolymers were obtained by blending with these modifiers. • Prepolymers exhibited processability capable for RTM manufacture. • Toughening was realized at no cost of thermal properties. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Low melting dual-functional phthalonitrile monomers were synthesized. • Prepolymers exhibited processability capable for RTM manufacture. • Glass transition temperatures of cured polymers were higher than 470 °C. • Impact strength reached 13.63 kJ m−2, capable as structural composite matrices. Abstract Low melting phthalonitrile monomers containing allyl and/or methoxyl groups were designed, synthesized and characterized. In order to evaluate their potential application in phthalonitrile resins, these monomers were blended with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-(4-aminophenoxy)phthalonitrile, then cured into polymers. Curing mechanisms of different prepolymers were proposed and compared, and processability, thermal and mechanical properties were characterized. The introduction of methoxyl units was found to postpone the curing, and thermal properties were slightly compromised. On the contrary, the usage of allyl was beneficial to both processability and thermal properties. More importantly, the impact strength for allyl-containing polymers could be as high as 13.63 kJ m−2, indicating such resin could be applied as high temperature structural composite matrices. [ABSTRACT FROM AUTHOR]