The ene reaction between maleimides and allyl-substituted aromatics

ABSTRACT:The bismaleimide (BMI)-modified novolac resin was synthesized by allylation of the novolac resin and its "Ene" reaction with BMI. The reactions were monitored by Fourier transform infrared analysis (FTIR). The morphology of the BMI-modified novolac resin changed with degree of allylation (i.e., the amount of BMI used). On the basis of the studies done by dynamical mechanical analysis (DMA), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FE-SEM), it was found that when the degree of allylation increased from 48 to 59%, the resin changed from a single-phase structure to a two-phase structure. From the research by thermogravimetric analysis (TGA) and DMA, it was found that the higher allyl-content (when Ͼ 48%) caused a decrease of the thermal properties and mechanical properties of the resultant resin. The BMImodified allyl novolac resin with 48% degree of allylation has the best thermal properties and the highest dynamic modulus in the current research.

Section: Introductionmentioning

confidence: 99%

Morphology transition of bismaleimide‐modified novolac resin

Zhang

Yan

et al. 2006

“…The maximum crosslinking occurs at an allyl phenol-phenyl maleimide molar ratio of 1 : 3. 15,16 This cure chemistry has been substantiated in subsequent investigations involving various polymer systems bearing these functional groups. 22 Hamerton extrapolated this cure chemistry to get allyl triazinemaleimide cocured matrix.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 94%

“…The reaction between phenyl allyl and maleimide groups is well established. 15,16 The reaction proceeds by a sequence of Ene reaction followed by Diels-Alder reaction, depending upon the cure temperature. 17 The network structure depends also on the backbone structure and also on the stochiometry of the allyl and maleimide groups.…”

Section: Introductionmentioning

confidence: 99%

Diallyl bisphenol A—novolac epoxy system cocured with bisphenol‐A‐bismaleimide—cure and thermal properties

Devi¹,

Nair²,

Ninan³

2007

Novolac epoxy (EPN)-2,2 0 -diallyl bisphenol A (DABA) resin system was modified by cocuring it with bisphenol A bismaleimide (BMI). Molar concentration of BMI in the stochiometric blend of EPN and DABA was varied from 0.5 to 2.0. The cure optimization was done using DSC, IR spectroscopy, and rheological studies. The curing proceeded by phenol-epoxy and Alder-ene reactions. The performance of the ternary Epoxy-Allyl phenolic-Bismaleimide system was evaluated through their thermal and dynamic mechanical characterization. BMI improved the overall thermal stability and the modulus of the result-ant composites. The increase in BMI concentration in the system resulted in enhanced glass transition temperature with a consequent improvement in high temperature performance typically estimated by their lap shear strength at high temperatures. The high temperature performance of the epoxy-phenol-bismaleimide (EPB) system was found to be far superior to the epoxy-phenol (EP)system.

“…10,19,21 Prepolymerization degree of the BMAN resin can be controlled by reaction condition. The BMAN resin with proper prepolymerization degree is a homogeneous, transparent and redbrown resin system, which can be easily dissolved in acetone without precipitation of BMI.…”

Section: Preparation and Characterization Of Bman Resinsmentioning

confidence: 99%

The effect of allylation degree on processing properties, thermal cure, and thermal properties of BMAN resins

Luo

Wei

Liu

et al. 2007

A series of allyl-functional novolac (AN) resins with various allylation degree, from 32.4 to 114.6%, were synthesized and blended reactively with 4,4 0 -bismaleimide biphenyl methane (BMI) at a weight ratio of 2.50 : 1 to get BMI-modified and allyl-functional novolac (BMAN) resins. Structural characteristics of the resins were determined by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance ( 1 HNMR) techniques. Processing properties of BMAN resin system was evaluated by solubility, rheology, and thermal gelation, and the results show that processing properties of BMAN resins were excellent and could be tailored by changing allylation degree of AN resins. Differential scanning calorimetry (DSC) was used to evaluate cure reactivity of BMAN resin system, and the results reveal that the resins with higher allylation degree possessed better cure reactivity. Thermal properties were evaluated by means of dynamic mechanical analysis (DMA) and thermogravimetry analysis (TGA) techniques. The results reveal that with increase in allylation degree of resins the thermal stability of BMAN resins increased because of increase in crosslinking density, but char-yields of the above resins at 8008C decreased in turn. Understanding of the relationship between allylation degree and properties of the resins would be useful to direct the design of material to meet different requirements of applications.