Benzoxazine/Bismaleimide Blends And Their Glass Cloth Reinforced Laminates

Polybenzoxazine (PBZ), a new type of phenolic resins, has many attractive characteristics such as high heat resistance, flame retardancy, and low cost of raw materials. Bismaleimide offers excellent mechanical properties, thermal stability, and electrical insulation properties over a wide range of temperatures. The blending of benzoxazine and bismaleimide could result in a improved matrice with advantageous combination of both the component polymers. More recently, the nitrile functionalized benzoxazine (CNBZ) have attracted great attention. This was because its nitrile groups produced the triazine ring during curing, which was similar to one formed from cyanate groups in dicyanate ester. Therefore, CNBZ will improve the performance better than common benzoxazine when blending with BMI. Furthermore, glass fibre (GF) reinforced laminates based on CNBZ/BMI blends were studied as well.The main contents and results are as follows:1. Blends of3,3’-Phenylmethanebis(3,4-dihydro-2H-l,3-benzoxazine)(BZ) and4,4’-bismaleimi-dodiphenyl methane (BMI) were prepared via via solvent method. The curing behaviors of the blends were studied by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and gelation time test. The thermal properties and mechanical properties of the cured blends were studied by dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA) and Electromechanical Universal Testing Machine. The results showed that the addition reaction between phenolic hydroxyl group and the double bond occurred except for the homopolymerizations of BZ and BMI. The curing temperature and the gelation time of the blends was lowered. The cured BZ/BMI blends exhibited excellent thermal properties. When BMI content was more than40%, the cured BZ/BMI blends exhibited higher glass transition temperatures (Tgs) than BZ and BMI homopolymers, which reached up to289℃. The5%and10%weight loss temperatures (Tds and Td10) reached up to387℃and422℃, respectively. Meanwhile, when BMI content was60%, shear strength of the cured BZ/BMI blends reached up to12.44MPa. Furthermore, glass cloth (GF) reinforced laminates based on the cured BZ/BMI blends were prepared and their mechanical properties, morphological were investigated. The results showed that the the enhanced mechanical properties were mainly due to the strong interfacial adhesions between GF and matrices, which was confirmed by SEM observations. When BMI content was40%, their tensile strength, flexural strength, and impact strength reached up to394MPa,490MPa, and160KJ-m"2, respectively2. A novel high-performance resin blend composed of nitrile functionalized benzoxazine (CNBZ) and bismaleimide (4,4’-bismaleimidodiphenyl methane)(BMI) was prepared via solvent method. The curing behaviors of the blends were studied by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and gelation time test. The thermal properties and mechanical properties of the cured blends were studied by dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and Universal Testing Machine. The results showed that the addition reaction between phenolic hydroxyl group and the double bond occurred except for the homopolymerizations of CNBZ and BMI. The curing temperature and the gelation time of the blends was lowered. The cured CNBZ/BMI blends exhibited excellent thermal properties. When BMI content was more than40%, the cured CNBZ/BMI blends exhibited higher glass transition temperatures (Tgs) than CNBZ and BMI homopolymers, which reached up to334℃. The5%and10%weight loss temperatures (Td5and Td10) reached up to383℃and412℃, respectively. Meanwhile, when BMI content was40%, the tensile strength, flexural strength, and shear strength reached up to69MPa235MPa, and12.9MPa, respectively, which exhibited the comparable mechanical properties with BT resin. Furthermore, the glass cloth (GF) reinforced laminates based on these blends were prepared. The results showed that when BMI content was40%, their tensile strength, flexural strength, and impact strength reached up to334MPa,593MPa, and145KJ·m-2, respectively.