End-functionalized thermoplastic-toughened phthalonitrile composites: influence on cure reaction and mechanical and thermal properties
TL;DR: In this paper, the feasibility of toughening novolac-phthalonitrile (NPN) resins using chemically modified poly(ether ether ketone) (PEEK).
Abstract: Phthalonitrile polymers are known for their high thermal stability and good mechanical properties. However, their brittle nature limits their application as structural composites in many critical areas. The present study investigates the feasibility of toughening novolac–phthalonitrile (NPN) resin using chemically modified poly(ether ether ketone) (PEEK). A telechelic PEEK bearing a phthalonitrile end group (PEEKPN) was synthesized via nucleophilic substitution of nitrophthalonitrile with the corresponding phenol–telechelic poly(ether ether ketone) (PEEKOH). Different compositions of NPN and PEEKOH–PEEKPN blends with curing agent, i.e. diaminodiphenylsulfone, were investigated for their cure behaviour and mechanical properties of their carbon fabric composites. In NPN–PEEKOH blends, crosslinking of the phthalonitrile groups was facilitated by phenol-mediated reactions resulting in the reduction of cure temperatures by around 130 °C with substantial improvement in thermal stability. Blending the resin with the thermoplastic enhanced the mechanical properties of the composites. The apparent flexural strength and impact strength of carbon fabric-reinforced composites were improved by more than 200 and 150%, respectively, on incorporation of 20 wt% PEEKOH in the NPN matrix. However, higher concentration of PEEKOH had a detrimental effect on the properties. Substitution of phenol end groups by phthalonitrile moieties led to integration of the PEEK moieties with the NPN matrix. However, it was not as conducive as PEEKOH for improving the matrix properties. The better performance of PEEKOH is attributed to the formation of polar heterocyclic groups like isoindoline by way of the phenol–nitrile reaction. © 2014 Society of Chemical Industry
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TL;DR: In this paper, a new type of nanocomposites based on a high performance bisphenol-A phthalonitrile resin and surface-modified alumina nanoparticles was prepared by a hot compression molding technique.
Abstract: A new type of nanocomposites based on a high performance bisphenol-A phthalonitrile resin and surface-modified alumina nanoparticles was prepared by a hot compression molding technique. The effect of adding different amounts of the reinforcing phase on the thermal and mechanical properties of the resulting nanocomposites was investigated. Thermogravimetric analysis showed that the starting decomposition temperatures and the residual weight at 800°C were highly improved upon adding the nanofillers. At 15 wt% nanoloading, the glass transition temperature and the storage modulus were considerably enhanced, reaching 346°C and 3.4 GPa, respectively. The tensile strength and modulus as well as the microhardness values increased with the increasing amount of the nanoparticles. The tensile modulus calculations were investigated using Series, Halpin-Tsai, and Kerner models. Haplin-Tsai model was found to reproduce the experimental data with the best accuracy. Estimation of the nanofillers shape factors for both Haplin-Tsai and Kerner models significantly improved the precision of the cited predictive models. The fractured surface of the nanocomposites analyzed by SEM exhibited homogeneous and rougher surfaces compared to that of the pristine resin. Finally, this new kind of nanocomposites is a highly attractive candidate for use in advanced technological applications such as the aerospace and military fields.POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers
38 citations
TL;DR: In this paper, a two-step, one-pot reaction was used to obtain high glass transition temperatures at around 400°C and outstanding thermo-oxidative stability with weight retention of 95% ranging from 539°C to 552°C, suggesting an improvement of thermal properties imposed by phenyl-s-triazine units.
38 citations
TL;DR: In this paper, a number of copolymers bearing varying proportions of propargyl and phthalonitrile groups on the same backbone and capable of self and co-curing to a thermally stable matrix have been synthesized.
33 citations
TL;DR: In this article, a silicon-containing phthalonitrile-terminated fluorene-based oligomer was synthesized by a novel method, and the structure was characterized by Fourier transfrom infrared spectroscopy, 1H NM.
Abstract: A novel silicon-containing phthalonitrile-terminated fluorene-based oligomer was synthesized by a novel method, and the structure was characterized by Fourier transfrom infrared spectroscopy, 1H NM...
32 citations
TL;DR: In this paper, a copolymer 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh) was modified with the hydroxyterminated poly(aryl ether nitrile) (PEN-OH).
Abstract: The thermosetting 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh) was modified with the hydroxy-terminated poly(aryl ether nitrile) (PEN-OH). Two different crosslinking reactions including the polymerization of the nitrile groups and the formation of triazines were coexisted in the BPh/PEN-OH system, which depended on the different curing temperature. Moreover, along with the processing of crosslinking, the microstructure changed to plastic fracture first and then became brittle fracture (T > 320 °C), which was observed from SEM. The copolymer system showed good mechanical properties, outstanding thermal stability (over 520 °C) and high char yield (86.1% at 600 °C). Furthermore, they exhibited excellent dielectric properties. Both the dielectric constant and dielectric loss were found to be relatively stable over a wide range of frequencies ranging from 100 Hz to 200 kHz. Moreover, the dielectric stability was also found with respect to temperature.
32 citations
References
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Patent•
09 Jan 1992TL;DR: In this paper, the authors proposed amine salts, reaction products of an aromatic amine and an aromatic sulfonic acid, which are used for di-phthalonitrile polymers.
Abstract: Polymerization or cure of di-phthalonitrile monomers or prepolymers by a curing agent selected from (a) an acid and an amine, (b) a salt of an acid and an amine, and (c) mixtures of (a) and (b). In a preferred embodiment, the curing agents are amine salts which are reaction products of an aromatic amine and an aromatic sulfonic acid. The use of the novel curing agents enhances curing rates and results in polymers which have high Tg.
28 citations
TL;DR: In this paper, the self-promoted curing behaviors and processing properties of 4-aminophenoxyphthalonitrile (APN)/epoxy resin (ER) copolymers were investigated by differential scanning calorimetry (DSC), dynamic rheological analysis and thermogravimetric analysis (TGA).
Abstract: Thermosetting blends of 4-aminophenoxyphthalonitrile (APN)/epoxy resin (ER) were investigated by differential scanning calorimetry (DSC), dynamic rheological analysis and thermogravimetric analysis (TGA). The self-promoted curing behaviors and processing properties of the APN/ER blends and prepolymers were studied by DSC and rheological analysis under dynamic and isothermal conditions. The APN/ER blends and prepolymers exhibited two-step polymerization reactions in the absence of any other curing additives. The APN/ER blends and prepolymers had large processing windows with low melt viscosity, and the size of the processing windows was dependent on the APN monomer concentration. The thermal behaviors of the APN/ER copolymers were studied by TGA. These cured copolymers exhibited decomposition temperatures over 367 oC in either flowing nitrogen or air, and high char yield at 800 oC of 68% under nitrogen atmosphere. Consequently, these studies revealed that the APN/ER system exhibits attractive self-promoted...
26 citations
Patent•
24 Aug 1981TL;DR: In this article, a phthalonitrile monr with a phenolic compound is obtained from polymerizing a poly(n) monr using a polycyclic acid.
Abstract: Phthalonitrile resins are obtained from polymerizing a phthalonitrile monr with a phenolic compound.
23 citations
TL;DR: In this paper, a polyimides with pendant phthalonitrile units were synthesized via the conventional two-step polymerization approach and the chemical structure of the PIs was confirmed by IR and 1H NMR spectra.
Abstract: New polyimides with pendant phthalonitrile units were synthesized via the conventional two-step polymerization approach. The chemical structure of the PIs was confirmed by IR and 1H NMR spectra. The thermogravimetric analysis and differential scanning calorimetry revealed that the thermal properties of the new PIs along with their solvent-resistance can be promoted after thermal treatment at 300 °C. This promotion can be attributed to the nitrile cure reaction of the phthalonitrile units indicated by the decrease in nitrile absorptions at around 2231 cm−1 of the IR spectra.
16 citations
TL;DR: A series of copolymers and glass fiber composites were successfully prepared from 2,2-bis [4-(3,4-dicyanophenoxy) phenyl] propane (BAPh), epoxy resins E-44 (EP), and polyarylene ether nitriles (PEN) with 4,4′-diaminodiphenyl sulfone as curing additive as discussed by the authors.
Abstract: A series of copolymers and glass fiber composites were successfully prepared from 2,2-bis [4-(3,4-dicyanophenoxy) phenyl] propane (BAPh), epoxy resins E-44 (EP), and polyarylene ether nitriles (PEN) with 4,4′-diaminodiphenyl sulfone as curing additive. The gelation time was shortened from 25 min to 4 min when PEN content was 0 wt % and 15 wt %, respectively. PEN could accelerate the crosslinking reaction between the phthalonitrile and epoxy. The initial decomposition temperatures (Ti) of BAPh/EP copolymers and glass fiber composites were all more than 350°C in nitrogen. The Tg of 15 wt % PEN glass fiber composites increased by 21.2°C compared with that of in comparison with BAPh/EP glass fiber composite. The flexural strength of the copolymers and glass fiber composites reached 119.8 MPa and 698.5 MPa which increased by 16.6 MPa and 127.3 MPa in comparison with BAPh/EP composite, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
14 citations