Phthalonitrile Resins Research Articles

Preparation of phthalonitrile resins containing siloxane linkages with improved processability

To improve the processability of biphenyl phthalonitrile resin, a flexible siloxane structure was introduced into the phthalonitrile monomer through molecular design, which was then blended with a biphenyl monomer to prepare phthalonitrile alloy resins. When the ratio of phthalonitrile monomer containing flexible siloxane to biphenyl phthalonitrile monomer was 1:1, the processing window widened from 58 to 110°C, as compared to that of biphenyl phthalonitrile. Due to the introduction of the biphenyl structure into the phthalonitrile alloy resins, the initial decomposition temperature of the silicon-containing phthalonitrile resin increased from 385 to 516°C. More importantly, the phthalonitrile alloy resin exhibited a high bending strength (66 MPa) and bending modulus (3762 MPa), indicating that it could be potentially applied as high temperature structural composite matrices. Furthermore, it provides a new strategy for processing phthalonitrile resins with a high melting point and narrow processing window.

High-performance boron-containing phthalonitrile resins

Boron-containing phthalonitrile resins with good thermal stability, good flame retardancy and good thermo-mechanical properties.

Modification on phthalonitrile containing benzoxazine with cyaniding diamine-type benzoxazine: Curing reaction and properties of their glass fiber-reinforced composites

Phthalonitrile resin is a kind of high-performance thermosetting resins. Decreasing the curing temperature and accelerating the curing reaction rate have become the focus of research on phthalonitrile modification. Based on the reactivity, thermal and mechanical properties of diamine-type benzoxazine, a monocyano-functionalized diamine-type benzoxazine (MD-cn) was synthesized and applied to modify bisphthalonitrile resin containing bisphenol-type benzoxazine/nitrile phenylenediamine (BA-ph/BAB). Curing reaction properties and curing mechanism of BA-ph/BAB/MD-cn were studied by gelation time, DSC, DRA and in-situ IR. Results showed that MD-cn could significantly boost the curing reaction rate and reduce its curing temperature of BA-ph/BAB. Meanwhile, glass fiber reinforced composites (BA-ph/BAB/MD-cn/GF) was prepared and their properties were studied. Results showed that MD-cn improved the crosslinking density and curing degree of BA-ph/BAB could make the BA-ph/BAB/MD-cn resin matrix possess higher stiffness. Therefore, BA-ph/BAB/MD-cn/GF composites exhibited higher flexural strength (494 MPa, increased 40%) and flexural modulus (26 GPa, increased 13%) as well as good dimensional stability. Compatibility between MD-cn and BA-ph/BAB was investigated by DMA and SEM. Moreover, with the increase of MD-cn content, the good thermal stabilities (T5%>404.5 °C, Yc, 800°C>66%) of cured BA-ph/BAB/MD-cn were obtained. Besides, interfacial adhesion properties of BA-ph/BAB/MD-cn/GF composite laminates were also studied.

Easy processable tris-phthalonitrile based resins and carbon fabric reinforced composites fabricated by vacuum infusion

Easy-processable phthalonitrile resins were prepared from tris-phthalonitrile phosphate monomer TPP ( tris(3-(3,4-dicyanophenoxy)phenyl)phosphate), bis-phthalonitrile RP ( bis (3,4-dicyanophenoxy)benzene) and novel viscosity reducing comonomer CPN ( 4-(4-cyanophenoxy)benzene-1,2-dicarbonitrile). It was shown that TPP is more resistant to hydrolysis than reported phosphate based phthalonitriles ( k = 8.2·10 -4 s -1 at 65℃ and pH 10). Two different type of curing agents: aromatic diamine DDS and 4-(4-aminophenoxy) phthalonitrile APN were used to study their effect on properties of the obtained resins and composites. Carbon fabric composites with APN -cured matrix fabricated by vacuum infusion demonstrated compression strength up to 633 MPa and 100% retention of ILSS after oxidative aging for 200 h at 300℃. Post-curing of the matrix at 375℃ resulted in growth of Tg but at the same time microcracking occurrence in the composite leading to decrease in mechanical properties and thermal aging sustainability. • Phthalonitrile resins for VIMP processing were developed based on TPP • Tris-phthalonitrile TPP is more resistant to hydrolysis than bis-phthalonitrile DPP • APN as curing agent provides higher strength of the composites than DDS • CFRP with PN-TPP-APN matrix retains mechanical properties after 200 hours at 300 °С

Toughening mechanism of phthalonitrile polymer: MD simulation and experiment

Based on the demand for materials in the aerospace field, we are researching the brittleness problem of phthalonitrile resin (PN75), a high-temperature resistant resin material. Combining molecular dynamics simulations with experiments in time-consuming and costly studies has become a meaningful way to reduce research and development cycle time and cost. In a world where high-performance computer simulations are capable of enormous computational scales with guaranteed reliability, experiments and characterization at the atomic-molecular scale are still challenging tasks. Revealing microscale mechanisms through atomic simulations and providing guidance for laborious, time-consuming, and expensive experiments is one of the current scientific hotspots. The free volume pore distribution of PN75 was analyzed using molecular dynamics (MD) simulations to reveal the primary mechanism of PN75 during toughening. Improving the scalability of the free volume cavity of PN75 creates an appreciable energy dissipation mechanism. The combination of experimental and MD simulation results verifies the usefulness of simulation as a guide for experiments. MD simulations can reduce complex experimental and characterization efforts, reveal experimental mechanisms at the nanoscale, and guide the design of polymers.

Fast-Processable Non-Flammable Phthalonitrile-Modified Novolac/Carbon and Glass Fiber Composites.

Phthalonitrile resins (PN) are known for their incredible heat resistance and at the same time poor processability. Common curing cycle of the PN includes dozens hours of heating at temperatures up to 375 °C. This work was aimed at reducing processing time of phthalonitrile resin, and with this purpose, a novolac oligomer with hydroxyl groups fully substituted by phthalonitrile moieties was synthesized with a quantitative yield. Formation of the reaction byproducts was investigated depending on the synthesis conditions. The product was characterized by 1H NMR and FT-IR. Curing of the resins with the addition of different amounts of novolac phenolic as curing agent (25, 50 and 75 wt.%) was studied by rheological and DSC experiments. Based on these data, a curing program was developed for the further thermosets' investigation: hot-pressing at 220 °C and 1.7 MPa for 20 min. TGA showed the highest thermal stability of the resin with 25 wt.% of novolac (T5% = 430 °C). The post-curing program was developed by the use of DMA with different heating rates and holding for various times at 280 or 300 °C (heating rate 0.5 °C/min). Carbon and glass fiber plastic laminates were fabricated via hot-pressing of prepregs with Tg's above 300 °C. Microcracks were formed in the CFRP, but void-free GFRP were fabricated and demonstrated superior mechanical properties (ILSS up to 86 MPa; compressive strength up to 620 MPa; flexural strength up to 946 MPa). Finally, flammability tests showed that the composite was extinguished in less than 5 s after the flame source was removed, so the material can be classified as V-0 according to the UL94 ratings. For the first time, fast-curing phthalonitrile prepregs were presented. The hot-pressing cycle of 20 min with 150 min free-standing post-curing yielded composites with the unique properties. The combination of mechanical properties, scale-up suitable fast-processing and inflammability makes the presented materials prospective for applications in the electric vehicle industries, fast train construction and the aerospace industry.

Rational Design of Fluorinated Phthalonitrile/Hollow Glass Microsphere Composite with Low Dielectric Constant and Excellent Heat Resistance for Microelectronic Packaging.

High-performance composites with a resin matrix are urgently required for electronic packaging due to their low dielectric constant, outstanding high temperature resistance, excellent corrosion resistance, light weight and easy molding. In this work, hollow-glass-microsphere (HGM)-filled fluorinated-phthalonitrile (PBDP) composites, with filler contents ranging from 0 to 35.0 vol.%, were prepared in order to modify the dielectric properties of the phthalonitrile. Scanning electron microscopy (SEM) observations indicate that the modified HGM particles were uniformly dispersed in the matrix. The PBDP/27.5HGM-NH2 composite demonstrates a low dielectric constant of 1.85 at 12 GHz. The 5% thermogravimetric temperature (T5) of composites with silanized HGM filler (481-486 °C) is higher than the minimum packaging-material requirements (450 °C). In addition, the heat-resistance index (THRI) of PBDP/HGM-NH2 composites reached as high as 268 °C. the storage modulus of PBDP/HGM-NH2 composites were significantly increased to 1283 MPa at 400 °C, an increase by 50%, in comparison to that of PBDP phthalonitrile resin (857 MPa). The excellent dielectric and thermal properties of the present composites may pave a way for comprehensive applications in electronic packaging and thermal management for energy systems.

Synthesis of Pyridine Heterocyclic Low-Melting-Point Phthalonitrile Monomer and the Effects of Different Curing Agents on Resin Properties.

A phthalonitrile monomer (DPTP) containing pyridine with sulfide bonds was prepared and cured into polymers using different curing agents under the same temperature-programmed process. We characterized and comprehensively evaluated the effects of different curing agents on the thermal and thermomechanical properties of phthalonitrile resin, showing that the DPTP monomer cured with naphthalene-containing curing agent exhibited the best performance among the three polymers. Differential scanning calorimetric (DSC) investigation manifested that the melting point of the DPTP monomer was 61 °C, with a processing window of about 170 °C, suggesting the presence of a wide processing range. Thermogravimetric analysis (TGA) demonstrated the outstanding heat resistance, T5%, of 460 °C in nitrogen, at the same time demonstrating superior long-term stability compared with other commonly used polymer materials, which proves the long-term usage under high temperatures of 300 °C. Dynamic mechanical analysis (DMA) revealed that the storage modulus at 50 °C was 3315 MPa, and the glass transition temperature (Tg) of the polymer was more than 350 °C. Therefore, DPTP resins have favorable thermal stability as well as prominent thermomechanical properties.

Fast curing phthalonitrile modified novolac resin: Synthesis, curing study and preparation of carbon and glass fibric composites

Phthalonitrile modified novolac (PNN) was synthesized in aim to develop a fast-curing resin for hot-pressing processing and characterized by NMR to confirm a full substitution of hydroxyl groups with phthalonitrile. PNN blended with high amounts (10–50 wt%) of the amine curing agents have been investigated by DSC, FT-IR spectroscopy and TGA, which revealed T5% = 420 °C. Curing times for the compositions were 4–16 min at 240 °C. The 50 min post-curing cycle for FRPs was selected based on DMA. Composites were fabricated via hot-pressing of prepregs including post-curing at 280 °C (providing Tg > 340 °C) in total of 60 min, which is the fastest curing cycle for thermosetting resins developed for applications up to 300 °C. Carbon and glass fabric reinforced polymers (CFRP and GFRP) were obtained by the developed program yielding integral composites with high mechanical properties and great heat resistance. Interlaminar shear strengths of the CFRP were up to 31 MPa and up to 70 MPa for GFRP. The latter which demonstrated retention of 75% of initial ILLS values after dwelling for 200 h at 300 °C. Thus, a new fast-processing phthalonitrile resin was developed for application in electric transport, aerospace and heat-resistant insulation.

Toughening effect of poly (arylene ether nitrile) on phthalonitrile resin and fiber reinforced composites

Toughening effect of poly (arylene ether nitrile) on phthalonitrile resin and fiber reinforced composites

Understanding curing dynamics of arylacetylene and phthalonitrile thermoset blends

AbstractTetrakis(phenylethynyl)benzene (TPEB), a high char yield arylacetylene resin, was blended with a resorcinol‐based PEEK™‐like oligomeric phthalonitrile resin (Res). We observed the influence of each polymer precursor on the structural changes and material dynamics of different mixtures of these resins during thermal curing to produce thermosets with high char retention. We provide insight to help understand fundamental processes that control and tune this complex thermally driven curing mechanism, which, to date, has not been well understood. We show that an equivalent blend of Res and TPEB mitigates the exothermic curing process and exhibits a low viscosity, which may facilitate processing of these thermosetting blends for composite manufacturing. To obtain a more comprehensive overview of the different dynamics of these polymers during curing, we correlated thermodynamic changes with rheology, materials characterization, and molecular dynamics derived from neutron scattering. Our efforts shed more light on the thermally driven chemical changes, physical transformation, and gelation dynamics that drive or accompany softening and curing of these two distinct crosslinking resin groups.

Multiple catalytic polymerization of phthalonitrile resin bearing benzoxazine moiety: Greatly reduced curing temperature

Phthalonitrile resin is a high-performance thermosetting resin with excellent thermal stability, good mechanical properties, low water absorption and low dielectric constant, thus it shows great potential in aerospace, marine, and electronic packaging. However, the extremely high polymerization temperature and long curing cycle limit the practical application of phthalonitrile resin. It is revealed that the active species released by ring-opening of benzoxazine can promote the polymerization of phthalonitrile and the polymerization temperature of phthalonitrile resin containing benzoxazine (BAph) could be reduced to 240–280 ℃, but there is still difficultly in practical application. In this study, dicyandiamide (DCA), which contains reactive nitrile group and active amino groups, was selected as the curing agent to catalyze the curing reaction of BAph. The reaction activity, curing process and curing behavior of BAph-dca were investigated by differential scanning calorimetry (DSC), gelatin time (tgel) measurement and dynamic rheological analysis (DRA). The polymerization mechanism of BAph-dca was studied by Fourier transform infrared spectroscopy (FTIR) and DSC. It was shown that with 10 wt% of DCA, the initial exothermic temperature decreased from 222.9 ℃ (neat BAph) to 159.4 ℃, the peak temperature of ring-opening polymerization of benzoxazine (Tp1) decreased from 255.9 ℃ to 203.2 ℃, and the peak temperature of nitrile polymerization (Tp2) decreased from 288.5 ℃ to 271.6 ℃. Importantly, polymer films can be obtained at 200 ℃, which is substantially lower than the curing temperature of typical phthalonitrile resin. Moreover, the polymer films cured at 200 ℃ showed good thermal stability. The polymer film with 3 wt% of DCA showed initial decomposition temperature (Td5) of the 412 ℃ and the char yield (Yc) of 72.09 % at 800 ℃. This study is of great significance in reducing the polymerization temperature of phthalonitrile resin and promote its practical application.

Simultaneous Enhancement of Polymerization Kinetics and Properties of Phthalonitrile Using Alumina Fillers.

Alumina particles are investigated as a potential catalyst for phthalonitrile polymerization and as a property enhancer. In this work, extensive characterizations were conducted on alumina-filled resorcinol-based phthalonitrile to differentiate between the catalytic effect and the filler effect. Thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy suggest the occurrence of chemical interaction between alumina fillers and phthalonitrile, which provides an insight into the better performance of alumina-filled phthalonitrile resins. This hypothesis is further supported by the additional Al–N peak observed in the X-ray photoelectron spectroscopy (XPS) analysis when alumina is added to phthalonitrile before curing, as well as the presence of an exothermic peak in the differential scanning calorimetry (DSC) analysis that indicates the catalytic polymerization of phthalonitrile. This catalytic phenomenon observed by the addition of alumina fillers is beneficial for the improvement of the conventionally slow curing process of phthalonitrile and, more importantly, is coupled with observable enhancement of thermomechanical properties of the composite.

Study on aromatic nitrile-based resins containing both phthalonitrile and dicyanoimidazole groups

In order to prepare aromatic nitrile-based resins with improved curing reactivity, thermal and thermomechanical properties, and to clarify the difference in curing activity between dicyanoimidazole and phthalonitrile groups, a novel class of autocatalytic aromatic nitrile-based resins named PNDCI which contains both dicyanoimidazole (DCI) and phthalonitrile (PN) groups were designed and synthesized. A method for evaluating the reactivity of nitrile groups using the absorption wavenumber of FTIR was proposed. PNDCI monomers have demonstrated higher activity for self-promoted curing reactions than benzimidazole-containing phthalonitrile monomers (BIPN). The introduction of DCI can change the curing pathway of PN and inhibit the formation of phthalocyanine ring which is an important cured product of PN resins. The data of TGA, DMA, etc. revealed that the cured products of PNDCIs showed outstanding thermal stability, long-term thermo-oxidative stability at high temperatures (425°C) and thermal mechanical properties, which is favorable for the preparation of high temperature resistant resins. • Aromatic nitrile-based (PNDCI)resins containing both dicyanoimidazole (DCI) and phthalonitrile (PN) were reported. • 2.The difference in curing activity of the nitrile group of PN and DCI was preliminarily investigated. • 3.The cured PNDCI resin exhibits excellent thermal and thermomechanical properties.

Melamine modified phthalonitrile resins: Synthesis, polymerization and properties

Phthalonitrile resin, as a thermosetting resin, possesses high chemical resistance, high thermal resistance, high thermo-oxidative stability and good mechanical properties. However, the extremely high curing temperature needed to achieve high curing degree severely limits its large-scale application. It is found that introduction of benzoxazine moities into phthalonitrile would increase the reactivity and decrease the curing temperature. In this work, phthalonitrile resin with melamine moiety (BAph-m) is synthesized by taking advantage of benzoxazine chemistry using melamine as amine source. Its chemical structure is confirmed by Fourier infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (1H NMR) spectra. Its curing reactivity, polymerization mechanism and the properties of the resultant polymers are systematically studied. It is found that the introduction of melamine reduces the content of oxazine ring, leaving active groups like phenolic hydroxyls and secondary amines as build-in catalysts. Consequently, the modified resins show much higher reactivity. The exothermic peaks corresponding to ROP of benzoxazine ring and curing of phthalonitrile groups of BAph-30 m decreased to 197.4 °C and 278.2 °C, 77.7 °C and 30.1 °C lower than those of neat BAph. The gelation time shortened from 892 s for BAph-2m to 231 s of BAph-30 m. Moreover, it is found that the build-in active groups could catalyze the reaction of benzoxazine moities and phthalonitrile groups to form phenolic Mannich bridge structures, triazine rings, phthalocyanine rings and isoindoline. The modified resins show very high thermal stability with BAph-30m-280 showing initial decomposition temperature (Td5) of 492 °C and char yield (Yc) of 79.9%, which is 35 °C and 6.8% higher than those of BAph-280.

Ceramic precursor-phthalonitrile hybrid with improved high heat resistance through constructing binary continuous phases

Achieving organic–inorganic hybrids with improved heat resistance above 500 °C using inorganic materials as filler remains a challenge because inorganic constitutes could not form continuous inorganic phases in hybrids. Here, we obtained organic–inorganic phthalonitrile hybrids with increased heat resistance using ceramic precursor (SiBCN) as the inorganic source. The results showed that hybrids formed Si-O bond between phthalonitrile and the ceramic precursors. The carbon fiber reinforced composites of hybrids exhibited high glass transition temperatures (over 700 °C). The hybrid with 30 wt% SiBCN displayed a high temperature for losing 10 % weight (above 555.4 °C (N2)), and high mass residue (over 75 % at 900 °C (N2)). The improved heat resistance of the hybrid was originated from the continuous inorganic phases derived from the ceramic precursors delaying transfer and escape for the small molecules generated in the phthalonitrile resin at elevated temperature. Furthermore, the hybrid showed excellent high-temperature stability of thermal conductivity. The as prepared organic–inorganic hybrids could potentially replace ceramic-based materials in servicing temperatures ranging from 500−700 °C.

Characteristics and Application of Eugenol in the Production of Epoxy and Thermosetting Resin Composites: A Review.

The review article presents an analysis of the properties of epoxy and thermosetting resin composites containing eugenol derivatives. Moreover, eugenol properties were characterized using thermogravimeters (TGA) and Fourier-transform infrared spectroscopy (FTIR). The aim of this work was to determine the possibility of using eugenol derivatives in polymer composites based on thermoset resins, which can be used as eco-friendly high-performance materials. Eugenol has been successfully used in the production of epoxy composites as a component of coupling agents, epoxy monomers, flame retardants, curing agents, and modifiers. In addition, it reduced the negative impact of thermoset composites on the environment and, in some cases, enabled their biodegradation. Eugenol-based silane coupling agent improved the properties of natural filler epoxy composites. Moreover, eugenol flame retardant had a positive effect on the fire resistance of the epoxy resin. In turn, eugenol glycidyl ether (GE) was used as a diluent of epoxy ester resins during the vacuum infusion process of epoxy composites with the glass fiber. Eugenol-based epoxy resin was used to make composites with carbon fiber with enhanced thermomechanical properties. Likewise, resins such as bismaleimide resin, phthalonitrile resin, and palm oil-based resin have been used for the production of composites with eugenol derivatives.

A High-Mechanical-Strength Carbon/Graphene Porous Composite with Improved EMI Shielding Derived from High Nitrogen-Containing Bio-based Adenine-Containing Phthalonitrile Resin

A High-Mechanical-Strength Carbon/Graphene Porous Composite with Improved EMI Shielding Derived from High Nitrogen-Containing Bio-based Adenine-Containing Phthalonitrile Resin

Boron-containing Phthalonitrile Resin: Synthesis, Curing Behavior, and Thermal Properties

Boron-containing Phthalonitrile Resin: Synthesis, Curing Behavior, and Thermal Properties

Preparation of novel bio-based imine-containing phthalonitrile resin through the nucleophilic reaction in green solvent

Nucleophilic reactions, as extensive and easily implementable reactions in organic chemistry, play a significant role in the molecular design of organic compounds and polymer materials. In current sustainable development strategies, nucleophilic reactions are also being shifted towards green chemistry. In this paper, phthalonitrile (PN) resin, a thermoset prepared by nucleophilic substitution reaction, was selected for a case study to investigate the application and reusability of the ‘green solvent’ dimethyl carbonate (DMC) in the nucleophilic substitution reaction. This research employed naturally existing vanillin and tyramine for the synthesis of a fully bio-based bisphenol bearing a Schiff base structure (VTBP). Then VTBP was converted to a novel bio-based PN (VTPN) through a nucleophilic substitution reaction in DMC, and the DMC was recovered and reused through a rotary evaporation. The structure, curing behavior, and performance of the cured resin of the synthesized VTPN were characterized. The results suggest that the Schiff base may promote and participate in the crosslinking of nitrile, with a relatively high performance achieved under moderate curing conditions. This study provides a new green implementation scheme for high-performance polymers prepared through nucleophilic reactions, as well as for the high-performance and efficient utilization of widely existing bio-based aldehydes and amines. • Bio-based phthalonitrile resin was synthesized in green solvent dimethylcarbonate. • Dimethylcarbonate was recovered and reused in the synthesis. • Imine unit was proved to promote the polymerization of phthalonitrile.