Novel phthalonitrile-based composites with excellent processing, thermal, and mechanical properties

Abstract

Phthalonitrile resins exhibit excellent thermostability and mechanical strength after curing. However, poor processability made them difficult to fabricate fiber-reinforced composites with desirable integrated performance. In this article, a novel mixed phthalonitrile resin was developed to be used as the matrix for glass fiber–reinforced laminates. Poly (aryl ether nitrile phthalazinone) oligomer end-capped by phthalonitrile units (PPEN-PN) was firstly designed and blended with bisphenol-based phthalonitrile monomers (BP-PN) (Figure 1), which were obtained according to the literature procedure. A novel mixed curing agent (zinc chloride and 4,4-diamine-diphenylsulfone) was also exploited to accelerate curing rate of the resins. Solubility tests, differential scanning calorimetry and rheological studies revealed that the mixed resins exhibited good processability with low processing viscosity. Thermal gravimetric analysis indicated that the cured resins were stable below 530 to approximately 570 °C in nitrogen atmosphere after low-cost curing procedure. In air, char yields of the resins were between 30 to approximately 40% when heated to 800 °C. The laminates reinforced by E-glass fiber cloth possessed a bending strength of 668 MPa with interlaminar shear strength of 84.6 MPa at room temperature. 50% of the strength and modulus was maintained when heated to 400 °C. Consequently, this type of laminates may be potential candidates for aerospace applications.

Enhanced properties of phthalonitrile resins reinforced by novel phthalonitrile-terminated polyaryl ether nitrile containing fluorene group

“…The laminates derived from BPAPN-5 exhibited bending strength and modulus above 855 MPa and 37 GPa, respectively, which was higher than those of APN-derived composites (535 MPa and 21.7 GPa, respectively). Also, these values were higher than that of other reported phthalonitrile composites, 24,25 which typically exhibited bending strength and modulus of 500-700 MPa and 20-35 GPa, respectively. As the BPPEN content was further increased to 15%, obvious decline in bending strength and modulus could be found, the value were 634 MPa and 24.4 GPa, respectively, which was only slightly higher than that of pristine APN-derived composites.…”

“…In addition, it was difficult to ensure homogeneity of the blends when inorganic nanoparticles were used as reinforcing components. In order to combine the advantages of these two strategies, well-compatible modifiers, such as phthalonitrile-terminated oligomers containing poly(ether ether ketone), 14 4-(4hydroxyphenyl)(2H)-2,3-phthalazin-1-one, 24 and benzoxazine, 3,25 were reported to be blended with phthalonitrile resins. Results showed that both the flexural strength and flexural modulus of the phthalonitrile composites could be significantly improved without obviously decrease in thermal stability.…”

Synthesis and Properties of A Low Melting Point Phthalonitrile Resin Containing High Density Nitrile Groups

“…Because of the high melting point and poor processability of the first generation of phthalonitrile monomers, flexible aromatic ether segments were introduced into the molecular structure of the monomers by Keller at Naval Laboratory (NRL) . At present, aliphatic aromatic ether, poly(ether imide), poly‐(arylene ether ketone), poly‐(arylene ether) and poly‐(arylene ether nitrile) have been reported. These monomers are usually prepared by the reaction of activated dihalogenated aromatic hydrocarbons and appropriate proportions of bisphenols to form phenolic intermediates, and then end‐capped with 4‐nitrophthalonitrile.…”

Investigation on curing reaction of phthalonitrile resin with nanosilica and the properties of their glass fiber‐reinforced composites

“…Due to the inherent brittleness of thermosetting resins, pure thermosetting resins were hardly used as structural, substrate, or functional materials. In order to improve the brittleness of thermosetting resins, continuous fiber, nanoparticles were widely applied to reinforce the thermosetting resins to fabricate composites with enhanced properties 1–4 . Compared with that of traditional inorganic metal materials, fiber‐reinforced composites possessed outstanding properties, such as, light weight, high strength and modulus, outstanding corrosion resistance, and easy processing, which were intensively investigated and greatly used in car industry, new‐energy industry, electronics industry, and so on.…”