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Allyl-functional phthalonitrile (DBPA-Ph) and bismaleimide (BMI) have been considered as advanced composite-matrix resins applied in various fields. In this work, self-promoted polymerization behavior and processability of DBPA-Ph/BMI system were investigated in detail. To further reveal the effect of BMI on the properties of DBPA-Ph/BMI system, the blends and the prepolymers of DBPA-Ph/BMI were prepared in different proportions. Their curing and rheological behaviors were investigated by differential scanning calorimetry and dynamic rheological analysis. The results further confirmed the possible reaction mechanisms and demonstrated that DBPA-Ph/BMI prepolymers exhibited good processability, which included wide processing window (approximately 75°C), low melting viscosity (<0.2 Pa·s), and better reactivity. The copolymers exhibited satisfactory thermal stabilities (T5% > 421°C, char yield at 600°C >70%). Moreover, the DBPA-Ph/BMI/glass fiber composite laminates were prepared and the effect of the curing temperature and BMI content on mechanical properties and dielectric properties were also investigated. The results show that the composite laminates exhibit favorable mechanical properties and weak frequency dependence of dielectric properties over a wide frequency range. Above all, the research on DBPA-Ph/BMI system could expand its applications in industry, especially in the areas, which require high temperature resistance and excellent mechanical and dielectric properties. [ABSTRACT FROM AUTHOR]

A prepolymer constituted with bisphthalonitrile containing allyl groups (DBPA-Ph) and 4, 4′-bis-(maleimidodiphenyl)methane (BMI) was prepared. The reaction between DBPA-Ph and BMI was characterized with FTIR. The copolymerization behavior and processability of DBPA-Ph/BMI prepolymer was studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The results of DSC indicated that the DBPA-Ph/BMI system presented two-stage thermal polymerization attributing to the ene reaction between allyl moieties and maleimide at low temperature (around 263°C) and the ring-form polymerization of cyano moieties at high temperature (around 332°C), respectively. The results of dynamic rheological analysis indicated, with the introduction of BMI, the curing properties of DBPA-Ph/BMI system improved. The DBPA-Ph/BMI copolymers were prepared with relatively shorter curing time and shown high glass transition temperature (>350°C). The DBPA-Ph/BMI/glass fiber composite laminates were prepared and exhibited relatively better mechanical properties (>440 MPa) and satisfactory thermal properties (>440°C). The outstanding glass transition temperature, better processability, desirable thermal and thermo-oxidative stabilities demonstrated the introduction of BMI would contribute to the application of DBPA-Ph. POLYM. COMPOS., 38:1591-1599, 2017. © 2015 Society of Plastics Engineers [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]

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]