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In this work, Phthalonitrile containing benzoxazine (BA‐ph) and Bisphenol A based cyanate ester (CE) were chosen as the matrix resin. Various amount of nano‐SiO2 was incorporated into BA‐ph/CE and their glass fiber‐reinforced composite laminates were fabricated. Curing reaction and processability of BA‐ph/CE/SiO2 blends were studied by differential scanning calorimetry and dynamic rheological analysis. Results showed that BA‐ph and CE exhibited good processability and curing reaction of BA‐ph/CE was not obviously affected by SiO2. Scanning electron microscope images of the composites showed that SiO2 particles were well dispersed in BA‐ph/CE matrix. Moreover, SiO2 could act as physical crosslinking points and diluent in matrix as well as between the glass fibers to improve the mechanical properties of composite laminates. As the results of dynamic mechanical analysis and thermogravimetry analysis, composite laminates possessed satisfactory Tg and good thermal stability. With incorporation SiO2 particles into matrix resin, dielectric constant and dielectric loss of BA‐ph/CE/SiO2/GF composites were increased and showed frequency dependence. [ABSTRACT FROM AUTHOR]

Secondary dispersion of the nano barium titanate (BaTiO 3 ) was performed to obtain the fiber-reinforced polyarylene ether nitrile-based (PEN) composite laminates with improved mechanical properties. BaTiO 3 /PEN composite films were prepared via casting with ultrasonic dispersion, and then the glass fiber-reinforced (GF) composite laminates were obtained by the hot-melting method, which were favored to realize the secondary dispersion of the BaTiO 3 nanoparticles. The fracture surface of the BaTiO 3 /PEN films and BaTiO 3 /PEN/GF composite laminates investigated by SEM showed that the BaTiO 3 dispersed homogenously both in the PEN matrix and the gaps between the fibers. The mechanical and thermo-mechanical properties of the laminates were characterized and results indicated that the nano-BaTiO 3 particles and fibers show enhanced synergistic effects. That is, with increasing the BaTiO 3 content, the flexural strength and modulus of the composite laminates increased correspondingly, as well as the glass transition temperatures. Additionally, with the introduction of nano-BaTiO 3 particles, the dielectric constants (>5.5 at 1 kHz) of the composite laminates were improved obviously and the low dielectric loss (˂0.02 at 1 kHz) was maintained. The temperatures at weight loss 5% ( T 5% ) of all the composite laminates with various content of BaTiO 3 were over 490 °C both in N 2 and air atomosphere. Good dielectric properties and outstanding thermo-mechanical properties would enable the PEN-based fiber-reinforced composite laminates as the candidates in the material fields of structure-functional integrations. [ABSTRACT FROM AUTHOR]

The curing behaviors and processability of 2,2-bis[4-(3,4-dicyanophenoxy)phenyl] propane (BAPh) and carboxyl-terminated butadiene acrylonitrile rubber (CTBN) were investigated using differential scanning calorimetry and dynamic rheological analysis. The results indicated that the introduction of CTBN significantly catalyzed the polymerization of the CTBN/BAPh system and that the processability of the CTBN/BAPh prepolymer could be controlled by temperature, processing time, and CTBN content. CTBN/BAPh/glass fiber (GF) composite laminates were prepared in this study. In terms of mechanical and dielectric properties, the CTBN/BAPh/GF composite laminate with 10 wt% CTBN content showed an outstanding flexural strength and modulus of 534 MPa and 32 GPa, respectively, as well as higher dielectric constant and lower dielectric loss compared with the BAPh/GF composite laminate. The results on thermal property showed that the CTBN/BAPh/GF composite laminate with 10 wt% CTBN could withstand a high decomposition temperature of 580°C under nitrogen and 520°C in air atmospheres. Hence, this work proposes an approach to improving the processability of phthalonitrile resin so as to further widen its industrial applications. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel bisphthalonitrile monomer containing allyl groups (DBPA-Ph) had been synthesized via the reaction of diallyl bisphenol A (DBPA) and 4-nitrophthalonitrile. The chemical structure of DBPA-Ph was confirmed by 1HNMR, 13CNMR, and FTIR spectroscopy. The curing behaviors and processability of DBPA-Ph were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The monomer manifested a two-stage thermal polymerization pattern. The first stage was attributed to the polymerization of allyl groups and the second to the ring-form polymerization of cyano groups. The result of dynamic rheological analysis indicated the monomer had wide curing window and the self-catalyzed curing behavior. DBPA-Ph polymers were prepared from the thermal polymerization with short curing time, showing high glass transition temperature (>350°C) and attractive thermal decomposition temperature (>430°C). The outstanding glass transition temperature, desirable thermo-oxidative stabilities, good processability and sound process conditions could provide more applications to the DBPA-Ph polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41203. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelet reinforced semi-crystal poly(arylene ether nitrile) (PEN/GN) nanocomposites were prepared by an economically and environmentally friendly method of twin-screw extrusion technique. The feasibility of using PEN/GN nanocomposites was investigated by evaluating their thermal behaviors, mechanical, and morphological properties. Thermal studies revealed that GN could act as nucleating agents but decreased the whole crystallinity in/of PEN/GN nanocomposites. Mechanical investigation manifested that GN had both strengthening effect (increase in flexural modulus and strength) and toughening effect (rise in the elongation and impact strength) on the mechanical performance of semi-crystal PEN nanocomposites. Heat treatment can further increase their mechanical performances due to the increased crystallinity and release of inner stress. With the small addition of GN (<5 wt%), the morphology of PEN was changed from brittle to ductile, and GN showed good dispersion and adhesion in/to the PEN matrix. This work shows that in the semi-crystal polymer/filler systems, besides the dispersion states of fillers and interactions between fillers and polymer matrices, the crystallinity of the nanocomposites affected by the existence of filler and the residual stress are also two key factors determining the mechanical properties. POLYM. COMPOS., 35:404-411, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The nitrile groups of 2,2-bis [4-(3,4)-dicyanophenoxy phenyl] propane (bisphthalonitrile; BAPh) can be cured by the nucleophilic phenol groups. Bisphenol A (BPA) can react with 4-nitrophathalonitrile to synthesize BAPh. Therefore, BPA was used as a novel curing agent to react with BAPh. The BAPh/BPA prepolymers and polymers were prepared by heat polymerization. The curing behaviors were characterized using differential scanning calorimetry, dynamic rheological analysis, and thermogravimetric analysis. The results indicate that BPA can decrease the melting temperature of BAPh, shorten the curing time of BAPh with lower curing temperature at 243°C, and widen the processing windows of BAPh to 95–120°C. Meanwhile, BAPh/BPA polymers could withstand temperatures up to 443°C under nitrogen atmosphere and 420°C in air when cured at 240°C for 10 h. The mechanical properties of BAPh/BPA polymers were investigated, and it exhibits a flexural strength of 75 to 122 MPa. Dynamic mechanical analysis was used to evaluate the dynamic mechanical properties of BAPh/BPA polymers. The polymers show glass transition temperature ranging from 244 to 299°C heating and cured to 240°C. Herein, the BAPh/BPA polymers can be a good candidate resin for high-performance polymeric materials. [ABSTRACT FROM AUTHOR]

An easy and efficient approach by using carboxyl functionalized CNTs (CNT-COOH) as nano reinforcement was reported to develop advanced thermosetting composite laminates. Benzoxazine containing cyano groups (BA-ph) grafted with CNTs (CNT- g-BA-ph), obtained from the in situ reaction of BA-ph and CNT-COOH, was used as polymer matrix and processed into glass fiber (GF)-reinforced laminates through hot-pressed technology. FTIR study confirmed that CNT-COOH was bonded to BA-ph matrices. The flexural strength and modulus increased from 450 MPa and 26.4 GPa in BA-ph laminate to 650 MPa and 28.4 GPa in CNT- g-BA-ph/GF composite, leading to 44 and 7.5% increase, respectively. The SEM image observation indicated that the CNT-COOH was distributed homogeneously in the matrix, and thus significantly eliminated the resin-rich regions and free volumes. Besides, the obtained composite laminates showed excellent thermal and thermal-oxidative stabilities with the onset degradation temperature up to 624°C in N2 and 522°C in air. This study demonstrated that CNT-COOH grafted on thermosetting matrices through in situ reaction can lead to obvious mechanical and thermal increments, which provided a new and effective way to design and improve the properties of composite laminates. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A series of bisphenol A (BPA)-based 2,2-bis-[4-(3,4-dicyanophenoxy)phenyl]propane (BAPh) prepolymers and polymers were prepared using BPA as a novel curing agent. Ultraviolet-visible and Fourier transform infrared spectroscopy spectrum were used to study the polymerization reaction mechanism of the BAPh/BPA polymers. The curing behaviors were studied by differential scanning calorimetry and dynamic rheological analysis, the results indicated that the BAPh/BPA prepolymers exhibit large processing windows (109.5-148.5°C) and low complex viscosity (0.1-1 Pa·s) at moderate temperature, respectively. Additionally, the BAPh/BPA/glass fiber (GF) composite laminates were manufactured and investigated. The flexural strength and modulus of the composite laminates are 548.7-632.8 MPa and 25.7-33.2 GPa, respectively. The thermal stabilities of BAPh/BPA/GF composite laminates were studied by thermogravimetry analysis. The temperatures at 5% weight loss ( T5%) of the composite laminates are 508.5-528.7°C in nitrogen and 508.1-543.2°C in air. In conclusion, the BAPh/BPA systems can be used as superior matrix materials for numerous advanced composite applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Copolymerizing behavior and processability of epoxy/benzoxazine containing cyano groups (EP/BA-ph) systems were investigated by differential scanning calorimetry and dynamic rheological analysis. The results showed that EP/BA-ph systems exhibited two characteristic peaks corresponding to ring-opening of benzoxazine and ring-formation of cyano groups, respectively. Compared with BA-ph, EP/BA-ph copolymer processability was improved and can be controlled by varying EP contents, processing temperature, and time. Then EP/BA-ph copolymers were employed to prepare EP/BA-ph/glass fiber (GF) composite laminates and their mechanical, morphological, and thermal properties were investigated. Compared with those of BA-ph/GF composites, the flexural strength, and modulus of EP/BA-ph/GF composites with 50 wt % EP content were increased by 13.5 and 20%, respectively. The enhancements in mechanical properties are mainly due to the strong interfacial adhesions between GF and matrices, which was confirmed by SEM observations. All EP/BA-ph/GF composite laminates are stable up to 510°C in air. EP/BA-ph/GF laminates will have potential applications in the areas where require of excellent mechanical properties and high temperature resistance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Poly (arylene ether nitrile) (PEN) is a kind of high-performance engineering plastic and their properties can be tuned by the copolymerization of various structural diphenols and dichloro (fluoro)-benzonitrile. In this work, a series of phenolphthalein and bisphenol AF based PEN (PP/BPAF-PEN) copolymers were designed and synthesized. Structures, molar weights, mechanical and thermal properties were studied. Results showed that PP/BPAF-PEN copolymers were successfully synthesized and exhibited good compatibility, outstanding thermal and mechanical properties. Besides, PP/BPAF-PEN exhibited excellent T g up to 260 °C (DSC), tensile strength of 120 MPa, high T d5% and char yields (>70%). With incorporation of –CF 3 into molecular chains, dielectric constant of PP-PEN (3.41 at 1 MHz) was decreased to 3.05 of PP/BPAF-PEN and dielectric loss was around 0.01. Hence, the obtained PP/BPAF-PEN copolymers possessing excellent properties could be applied as the candidates in flexible printed circuit (FPC) substrate. • PP/BPAF-PEN copolymers were synthesized and results showed that the copolymers exhibited well compatibility. • PP-PEN possessed excellent T g (260 °C) and mechanical properties (tensile strength > 120 MPa, tensile modulus > 3434.6 MPa). • PP/BPAF-PEN gained dielectric constant of 3.05 at 1 MHz and all of PP/BPAF-PENs exhibited T g > 200 °C (by DSC). • Thermal stability was enhanced with incorporation of BPAF into molecular chains. [ABSTRACT FROM AUTHOR]