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Carbon foams with channel like pores have been prepared by pyrolysis of a thermosetting resin system; bismaleimide (BMI) modified allyl novolac (BAN) as carbon precursor and polyvinyl acetyl fibers (PVAF) as an organic sacrificial template. For improving the cross-linking density and glass transition temperature, dicumyl peroxide (DCP) was chosen as a curing initiator and compared the results with that of the most commonly used Hexamethylenetetramine (HTMA). After pyrolysis at 1000 °C, the resulting PVAF/HTMA/BAN carbon foam developed excessive voids with linear lengths and widths up to 3 and 0.25 mm respectively. Excessive bubbling of discrete self-curable BMI resin molecular chains surrounded by phenolic hydroxyl groups created such excessive voids and gaps. The PVAF/DCP/BAN carbon foam exhibited no such voids and the shape of the pores replicated the shape of PVAF template. Channel like pores were orientated at random with a non-cylindrical, flat, or kidney bean shape cross section with a maximum dimension of 25–50 μm. Moreover, general characteristics were studied including density, porosity, open cell, pore-size distribution, thermal conductivity and flexural strength. Results have showed that the PVAF/DCP/BAN carbon foam possessed improved properties including density, thermal conductivity and flexural strength of 0.53 g cm −3 , 0.87 W m −1 K −1 and 19.12 MPa respectively. [ABSTRACT FROM AUTHOR]

A thermosetting resin system has been developed by the copolymerization of allyl phenoxy, bismaleimide (BMI), and diallyl bisphenol A and optimized using response surface methodology. An optimized modified resin system with enhanced properties was achieved based on empirical second-order models expressing the relationship between the modifier contents and the mechanical properties. Dicumyl peroxide (DCP) was selected as initiator to further improve the curing behavior and mechanical properties of the optimized resin system. The effect of initiator contents on impact, flexural strength, and heat distortion temperature was also investigated. The curing behavior, morphology, and thermal stability of the optimized resin were carefully characterized using differential scanning calorimeter, scanning electron microscope, and thermogravimetric and dynamic mechanical analyzers, respectively. For evaluating the efficiency of modified BMI resin system, laminated composites using glass fiber cloth were fabricated using a hot press and tested for mechanical properties. The results showed that the DCP reduced the curing temperature significantly, improved the curing process, and proved to be very effective in heat resistance. Meanwhile, the laminated composite with initiator showed 13–27% higher mechanical properties and 5–7% higher retention rate at high temperature when compared with the neat resin composite system. The optimized resin system with higher mechanical properties, good heat resistance, and better manufacturability can be used as matrix resin for making advanced fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

A thermosetting resin system, bismaleimide (BMI) modified allyl novolac (BAN), was developed via reactive blending of formaldehyde and catalyst drop wise to improve the extent of reaction between BMI and phenol-carbenium ions. For improving the curing behavior and mechanical properties, dicumyl peroxide (DCP) was selected as a novel curing initiator to compare with hexamethylenetetramine (HTMA) which is the most common curing initiator used in the manufacture of phenolic resins. BAN was characterized by 1H nuclear magnetic resonance and Fourier transfer infrared spectroscopy. Curing behavior with initiators was analyzed by differential scanning calorimetry and glass transition temperature of the cured resins was examined by dynamic mechanical analysis. For evaluating efficiency of the modified system, composite samples using polyvinyl acetyl fiber were molded and tested for flexural properties before and after ageing at 150°C for 1,000 h. The morphology of composite samples was examined by scanning electron microscope, and the effects of the incorporated initiators on the mechanical and thermal properties of composite were investigated. The results indicated that the initiators reduced the curing temperature effectively and improved the curing process. DCP proved to be more effective in crosslinking and heat resistance than HTMA. Meanwhile, the molded composite with DCP showed higher mechanical properties before and after ageing when compared with HTMA curing initiator. Therefore, DCP/BAN resin system with good heat resistance, higher mechanical properties, and better process ability can be applied as matrix resin for the manufacturing of advanced fiber reinforced composites. POLYM. COMPOS., 37:2260-2271, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT For reducing the cure temperature and improving the thermal stability and mechanical properties, a thermosetting resin system composed of novolak and bismaleimide (BMI) was developed by reactive blending and using dicumyl peroxide (DCP) as a novel curing agent. Novolak was allylated and reacted with BMI to produce bismaleimide allylated novolak (BAN), and the effect of DCP on flexural, impact and heat distortion temperature of cured resin were investigated. On the basis of improved mechanical and thermal properties at 0.5% DCP contents, the curing behavior of DCP/BAN resin system was evaluated by DSC analysis. Ene, Diels-Alder, homo-polymerization and alternating copolymerization which occurred in DCP/BAN resin system were further verified using FTIR at sequential cure conditions from 140 to 200°C. Kissinger and Ozawa-Flynn-wall methods were used to optimize the process and curing reactions of DCP/BAN resin system. The results showed that the addition of 0.5% DCP in BAN reduced the curing temperature and time of the modified resin. For evaluating process ability of the modified system, composite samples using polyvinyl acetyl fiber were molded and tested for flexural properties. The resulting samples showed better flexural properties when compared with the composite made with neat BAN. The modified 0.5% DCP/BAN resin system with good mechanical properties and manufacturability can be used for making bulk molding compounds and fiber reinforced composites required in various commercial and aerospace applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41829. [ABSTRACT FROM AUTHOR]