High Performance Miscible Polyetherimide/Bismaleimide Resins with Simultaneously Improved Integrated Properties Based on a Novel Hyperbranched Polysiloxane Having a High Degree of Branching

Synthesis of a Novel Hyperbranched Polyimide for Reinforcing Toughness and Insulating Properties of Bismaleimide Resin

Bismaleimide (BMI) resin has great potential in aerospace, electronic, and machinery fields due to its extraordinary thermal stability. Owing to BMI's lower impact strength, various modified BMI resins have been prepared using CTBN, PEEK, fillers, and hyperbranched polymer to achieve higher impact strength. However, enhancement of toughness causes deterioration of other performance, such as Tg, thermal stability, and brittleness. In this work, BMI resin modified by hyperbranched polyimide (HBPI) was obtained. HBPI designed with flexible segments, unsaturated bonds, and a low degree of branching was synthesized. FT-IR and ¹³C-NMR were applied to confirm the successful fabrication of HBPI. The mechanical strength and dielectric properties of cured BMI resin containing various levels of HBPI were analyzed systematically. The impact and bending strength were improved significantly with increased HBPI content. When the content of HBPI is 40 wt.%, the impact strength and bending strength reach the maximum value of 32 kJ/mm and 88 MPa. In addition, the BMI cured with HBPI exhibits enhanced bending modulus to the value of 5.9 GPa. Furthermore, the dielectric strength of cured resin was improved to 28.3 kV/mm. The improved mechanical strength and enhanced dielectric properties are attributed to the increasing free volume induced by HBPI. These results indicate the promise of BMI resin modified by HBPI applied in insulating coatings and low dielectric laminates used in high frequency.

Enhanced tribological properties of bismaleimides with a novel hybrid silicon dioxide containing amino groups

To improve the tribological properties of bismaleimide (BMI) resin, silicon dioxide nanoparticles with imino and terminal functional amino groups were prepared through a sol–gel process to form a novel SiO2-NH2 hybrid. The as-prepared hybrid was then applied as a modifying agent for the BMI matrix to obtain SiO2-NH2/BMI composites. Compared to those of pure BMI resin, the volume wear rate and friction coefficient of the SiO2-NH2/BMI composites decreased significantly, while the wear mechanism changed from fatigue (BMI) to adhesive (SiO2-NH2/BMI) wear. This improvement in the tribological properties of the SiO2-NH2/BMI composites was attributed to the appropriate SiO2-NH2 added content, which endowed the BMI with excellent mechanical and thermal-resistant properties. Thus, the SiO2-NH2/BMI composites could resist the external load and excessive heat during the friction process.

Synthesis of a benzoxazine monomer contained hyperbranched polysiloxane and the characteristics of its polymer alloys blend with bismaleimides

A novel benzoxazine monomer contained hyperbranched polysiloxane structure (HBPSi-BOZ) was synthesized via a solvent process based on the polyformaldehyde, aniline, and a new hyperbranched polysiloxane with terminal amino groups (HBPSi-NH2). The HBPSi-BOZ was then used as modified phase to blend with bismaleimides (BMIs) resin, and a polymer alloy HBPSi-BOZ/BMI was successfully prepared. The thermal resistant properties, mechanical properties, and tribological properties of HBPSi-BOZ/BMI resins with different contents of HBPSi-BOZ prepared were researched to get an optimal ratio. The thermogravimetric analysis was also carried out to study the polymerization process and stability of HBPSi-BOZ/BMI resins. The results showed that as the thermal resistance increased, the wear resistance and mechanical properties of HBPSi-BOZ/BMI resins were also enhanced.

Effect of the Ratio of Acetylacetate Groups on the Properties of a Novel Plant-Based Dual-Cure Coating System

A novel plant-based dual-cure coating system based on a Michael addition reaction between bismaleimide (BDM) and modified acetoacetylated castor oil was developed. The BDM has a high reactivity toward acetylacetate groups, and the catalyst 1,4-diazabicyclo[2.2.2]octane (TEDA) was optimized by the rheological viscosity. The gel was characterized by Fourier transform infrared (FTIR) spectroscopy. Then, three films were prepared with the TEDA catalyst and analyzed with solid-state 13C NMR and FTIR spectroscopy. The thermal and mechanical properties of the three films were characterized by differential mechanical analysis, thermogravimetric analysis, and differential scanning calorimetry. We found that the cross-linking density, glass transition temperature (T g), and Young's modulus of the coating films increased with an increase in the ratio of acetylacetate groups from the modified acetoacetylated castor oil. This is the first study of the reaction of BDM with plant-based acetylacetate groups. Importantly, a quantitative ratio of acetylacetate groups can be obtained by a thiol-ene coupling reaction and a transesterification reaction, resulting in the formation of films having excellent performance.

Preparation and characterization of a novel benzoxazines/bismaleimide/2,2′-diallylbisphenol A blend with multiphase structures

Novel benzoxazine (BOZ)/bismaleimide (BMI)/2,2′-diallylbisphenol A (BA), with a multiphase structure, was successfully prepared under the catalysis of methyl p-toluenesulfonate (PTSM) through reaction-induced phase separation. The curing reaction of BOZ with BMI and ring-opening polymerization of BOZ under the catalysis of PTSM were studied by Fourier transform-infrared spectroscopy and differential scanning calorimetry analyses, respectively. Mechanical measurements, thermogravimetric analysis, and microanalyses were conducted to assess the toughness and morphology of the composite. The reaction between BOZ and 4,4′-bismaleimidodiphenyl methane (BDM) occurs at a relatively high temperature. The ring-opening reaction of BOZ starts at a low temperature of 100°C because of the catalysis of PTSM. The BOZ/BDM/BA system with an appropriate amount of BOZ significantly improves the impact strength and flexural strength compared with those of the BA/BDM resin. The BOZ/BDM/BA system with PTSM also features high impact strength and flexural strength. Scanning electron microscopy images and energy-dispersive spectroscopy results show that BOZ-rich phase is dispersed in BDM-rich phase in the BOZ/BDM/BA system with PTSM. Thermogravimetric data show that the BOZ/BDM/BA blend with a multiphase structure exhibits superior thermal resistance to those of the BOZ/BDM/BA and BA/BDM resins. The formation mechanism of the ternary system under the catalysis of PTSM is elucidated with Gibbs free energy theory.

Mechanical and thermal properties of a novel bismaleimide matrix resin for high-performance composite materials

A novel bismaleimide matrix resin of amino-polythioetherimide (PTEI-N)/4,4′-bismaleimidodiphenyl methane (BDM)/2,2′-diallylbisphenol A (BA) was prepared. Mechanical measurements, dynamic thermomechanical analysis, thermogravimetric analysis (TGA), and microanalyses were conducted to assess the mechanical properties, thermal resistance, and morphology of the modified resin. Results demonstrate that the addition of PTEI-N has significant effects on the mechanical properties of the BDM/BA system. Compared with the pure BDM/BA resin, the PTEI-N/BDM/BA system markedly improves the tensile strength, flexural strength, and impact strength, given an appropriate amount of PTEI-N. Scanning electron microscopic and energy-dispersive spectroscopic results show that PTEI-N is distributed uniformly in the BDM/BA system, and the interfacial compatibility between the PTEI-N and BDM/BA phase is excellent. TGA shows that the BDM/BA resin continues to exhibit good thermal resistance with a suitable dosage of PTEI-N. These changes in properties are closely correlated with the addition of PTEI-N. The PTEI-N/BDM/BA resin system shows potential applications in many fields.

Effects of silane-modified multiwalled carbon nanotubes and 9,10-dihydro-9-oxa-10 phosphaphenanthrene-10-oxide on the flame retardancy and mechanical properties of bismaleimide resin

In this article, the multiwalled carbon nanotubes modified by γ-aminopropyltriethoxysilane (MWCNT-APTES) and 9,10-dihydro-9-oxa-10 phosphaphenanthrene-10-oxide (DOPO) were added into the 4,4′-bismaleimidophenyl methane (BDM)/2,2′-diallyl bisphenol A (DBA) resins to prepare the flame retardant resins. Morphological observations reveal that the MWCNT-APTES is homogeneously dispersed in the matrix. The impact strength of the resin is improved by adding MWCNT-APTES. Meanwhile, BDM/DBA containing DOPO/MWCNT-APTES achieves vertical burning (UL-94) V-0 rating and a higher limiting oxygen index. Thermogravimetric analysis and scanning electron microscopy measurements have demonstrated that MWCNT-APTES resulted in the increase in char yield and the formation of the thermally stable carbonaceous char. The results of Raman show that the MWCNT-APTES can enhance the graphitization degree of the resin during combustion. All the investigations show that the combination of DOPO and MWCNT-APTES is an effective additive to develop high-performance resins with attractive flame retardance and mechanical properties.

Significantly improving mechanical, thermal and dielectric properties of cyanate ester resin through building a new crosslinked network with unique polysiloxane@polyimide core–shell microsphere

Tough, rigid and thermally resistant resins with outstanding dielectric properties were developed based on polysiloxane@polyimide core–shell microspheres and cyanate ester.

Preparation and characterization of a novel composite of polythioetherimide/bismaleimide/2,2′-diallylbisphenol A

A novel composite of polythioetherimide (PTEI)/bismaleimide (BMI)/2,2′-diallylbisphenol A (BA) was prepared. Mechanical measurements, dynamic thermomechanical analysis, and microanalysis were conducted to assess the toughness and morphology of the composite. Results demonstrate that the addition of PTEI has significant effects on the mechanical properties of the BMI/BA system. Compared with the BMI/BA resin, the PTEI/BMI/BA system significantly improves the impact strength and bending strength, given an appropriate amount of PTEI. Scanning electron microscope (SEM) images and energy dispersive spectroscopy results show that PTEI is distributed uniformly in the PTEI/BMI/BA system and that the interfacial compatibility between the PTEI and BMI/BA phase is excellent. Thermogravimetric and dielectric analyses were also conducted to infer the thermal and dielectric properties of the composite. With a suitable addition of PTEI, the BMI/BA resin still exhibits good thermal resistance and dielectric constant and loss values of the blends still retain good stability in a frequency band from 10 MHz to 60 MHz. All these changes in properties are closely correlated with the addition of PTEI.

The effect of functionalized benzoxazine with allyl groups on the dielectric, mechanical and thermal properties of BMI/BADCy composites

The incorporation of functionalized benzoxazine with allyl groups into BMI/BADCy composites can induce an interpenetrating network (IPN) structure and the fracture surface will change from a riverlike shape to a ductile sunken shape.