Cyclohexane and phosphorus based benzoxazine-bismaleimide hybrid polymer matrices: thermal and morphological properties

Preparation and Characterization of Bismaleimide-Resin-Based Composite Materials

This study utilized bismaleimide (BMI) resin, reinforced with introduced ether bonds, as a binding matrix, in combination with silicon carbide (SiC), for the fabrication of composite materials. A thorough investigation was conducted to assess the influence of diverse processing parameters on the mechanical properties and high-temperature thermo-oxidative stability of these composites. Experimental results indicate a notable improvement in the mechanical properties of the composites upon the incorporation of ether bonds, in contrast to their unmodified counterparts. The variation in performance among composites with different ratios and molding densities is apparent. Within a certain range, an increase in resin content and molding density is correlated with improved bending strength in the composites. With a resin content of 27.5 vol% and a molding density of 2.31 g/cm3, the composite achieved a maximum flexural strength of 109.52 MPa, representing a 24% increase compared to its pre-modification state. Even after exposure to high-temperature heat treatment, the composites displayed commendable mechanical properties compared to their pre-ether bond modification counterparts, maintaining 74.5% of the strength of the untreated composites at 300 °C. The scanning electron microscopy (SEM) microstructures of composite materials correlate remarkably well with their mechanical properties.

The effect of preparation conditions of chalcone based benzoxazine/magnetite nanocomposites on magnetization properties

In the current study, a hydroxylated chalcone (1-phenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, 4-aminobenzoic acid, and paraformaldehyde were combined in ethanol/toluene solvent to form a new benzoxazine monomer. 1H NMR and FTIR analysis were used to confirm the produced monomer. Polybenzoxazine was prepared by the thermal curing of chalcone-based benzoxazine monomer and examined using FTIR and XRD. Magnetite nanoparticles were prepared using two different solvents and mixed with benzoxazine monomer at various ratios, followed by insitu thermal curing to prepare polybenzoxazine/magnetite nanocomposites. These nanocomposites were analyzed by FTIR, XRD, DSC and TGA were used to examine the thermal characteristics of the resulted materials. The surface morphology was investigated using SEM, and the magnetic property was measured by VSM. The resulting benzoxazine monomer has a low curing temperature (160 °C). The addition of nanoparticles of magnetite to benzoxazine improved its thermal stability. Also, the inclusion procedure of magnetite into benzoxazine has a significant impact on its saturation magnetization.

Benzoxazine Containing Fluorinated Aromatic Ether Nitrile Linkage: Preparation, Curing Kinetics and Dielectric Properties

Benzoxazine containing fluorinated aromatic ether nitrile linkage (FAEN-Bz) had been synthesized from 2,6-dichlorobenzonitrile, 4,4'-(hexafluoroisopropylidene)diphenol (bisphenol AF), 3-Aminophenol, formaldehyde, phenol by condensation polymerization and Mannich ring-forming reaction. Structures of the monomer were verified by Proton NMR spectrum (1H-NMR) and Fourier transform infrared spectroscopy (FTIR). Curing behaviors and curing kinetics of designed monomers were investigated and discussed. The activation energy was calculated and possible polymerization mechanisms were also proposed. Then, properties of cured polymers including crosslinking degrees, thermal decomposition, surface wettability and energy, and dielectric properties were studied and discussed. Additionally, programmed integral decomposition temperature (IPDT) was also used to evaluate the thermal stability of final polymers. Results indicated that the incorporation of benzoxazine and nitrile resulted in increased thermal stability and char yields. Moreover, the surface wettability and dielectric properties of poly(FAEN-Bz) can be easily controlled by tuning the curing temperatures and time.