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.

Characterization of Mechanical, Electrical and Thermal Properties of Bismaleimide Resins Based on Different Branched Structures

Bismaleimide (BMI) resin is an excellent performance resin, mainly due to its resistance to the effect of heat and its insulating properties. However, its lack of toughness as a cured product hampers its application in printed circuit boards (PCBs). Herein, a branched structure via Michael addition was introduced to a BMI system to reinforce its toughness. Compared with a pure BMI sample, the flexural strength of the modified BMI was enhanced, and its maximum value of 189 MPa increased by 216%. The flexural modulus of the cured sample reached 5.2 GPa. Using a scanning electron microscope, the fracture surfaces of BMI samples and a transition from brittle fracture to ductile fracture were observed. Furthermore, both the dielectric constant and the dielectric loss of the cured resin decreased. The breakdown field strength was raised to 37.8 kV/mm and the volume resistivity was improved to varying degrees. Consequently, the resulting modified BMI resin has the potential for wide application in high-frequency and low-dielectric resin substrates, and the modified BMI resin with a structure including three different diamines can meet the needs of various applications.

High toughness and excellent electrical performance bismaleimide resin modified by hyperbranched unsaturated polyester of flexible aliphatic side chains

Because of its flawed toughness, the scope of application of bismaleimide resin (BMI) in the field of aeronautics, industry and electricity is greatly restricted. Herein, a novel Hyperbranched unsaturated polymers (HBP) with the flexible chains grafted was incorporated to reinforce BMI resin’s toughness, where the new interpenetrating networks (IPN) structure was formed. The rich unsaturated double bond of HBP polyester could react with the BMI resin for chemical crosslinking and be used for the toughening agent. 13C-NMR and FT-IR were used to characterize HBP’s hyperbranched structure. Consequently, after adding 20 wt.% HBP, the impact strength of BMI modified by HBP increased by 211.1%. In comparison with neat BMI, the flexural strength of BMI modified by HBP was enhanced by 209.3%. It is worth noticing that HBP available in BMI resin significantly improved its electrical performance.

Characterization and properties of high-temperature resistant structure adhesive based on novel toughened bismaleimide resins

A series of high-temperature resistant structural adhesives were prepared based on the copolymerization of 4,4′-bismaleimidediphenylmethane (BDM) and 2,2′-diallylbisphenol A (DABPA) together with a novel maleimide-capped polyetherimide containing cardo side groups (mPEI-C) as toughening agent. The chemical structure of the adhesives and their cured networks was characterized by Fourier transform infrared (FTIR) spectrometer. Their curing behavior and kinetics were analyzed using differential scanning calorimetry (DSC). The thermal properties, mechanical properties, bonding strength and moisture absorption behavior of the cured products were investigated by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA), etc. The modified resin system with mPEI-C exhibit similar curing behavior, and the apparent activation energy ( E a) and reaction order ( n) are equal to around 85.14 kJ/mol and 0.91, respectively. With increasing mPEI-C contends, the thermal stability is improved, the char yield is increased from 26.5% to 37.1%, and the glass transition temperatures have a slight decrease. The maximum flexural strength, impact strength and bonding strength are increased by 28.4%, 93.1% and 44.6%, respectively. The results of hygrothermal aging experiments exhibit the addition of mPEI-C has no obvious influence on the hygroscopicity of the modified resins.

Improved thermal and mechanical properties of bismaleimide nanocomposites via incorporation of a new allylated siloxane graphene oxide

A thermosetting resin system based on bismaleimide (BMI) has been developed via copolymerization with 4,4′-diaminodiphenylsulfone in the presence of a newly synthesized graphene oxide, modified using allylated siloxane (AS-GO). The curing behavior of the AS-GO-containing resin system was evaluated using curing kinetics. The dispersibility of AS-GO in the resin was observed through polarizing optical microscopy (POM), which indicates that AS-GO has good dispersibility in the resin due to GO modified with allylated siloxane which has a good phase compatibility with BMI. The effect of AS-GO on the thermomechanical and mechanical properties of the cured modified resin was also studied. Results of thermogravimetric analysis indicated that the cured sample systems display a high char yield at lower concentrations of AS-GO (≤0.5 wt%) with an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (T_g) with increasing AS-GO content was observed. Mechanical property analyses revealed a possible effect of AS-GO as a toughener, and the results showed that an addition of 0.3% AS-GO maximized the toughness of the modified resin systems, which was confirmed by analysis of fracture surfaces.

A thermosetting resin system based on bismaleimide has been developed via copolymerization of a new allylated siloxane graphene oxide.

Enhancement of Thermal and Mechanical Properties of Bismaleimide Using a Graphene Oxide Modified by Epoxy Silane

A thermosetting resin system, based on bismaleimide (BMI), has been developed via copolymerization of 4,4′-diaminodiphenylsulfone with a newly synthesized graphene oxide modified using epoxy silane (ES-GO). The effect of ES-GO on the thermomechanical and mechanical properties of cured modified resin was studied. To evaluate the efficiency of the modified BMI systems, the composite samples using glass fiber cloth were molded and tested. Thermogravimetric analysis indicates that the cured sample systems displays a high char yield at lower concentrations of ES-GO (≤0.5 wt.%), suggesting an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (Tg) with increasing ES-GO content was observed. Analysis of mechanical properties reveals a possible effect of ES-GO as a toughener. The results also showed that the addition of 0.3 wt.% ES-GO maximizes the toughness of the modified resin systems, which was further confirmed by the result of analysis of fracture surfaces. At the same time, a molded composite with ES-GO showed improved mechanical properties and retention rate at 150 °C as compared to that made with neat resin.

Curing behavior, thermal, and mechanical properties of N,N′-(4,4′-diphenylmethane)bismaleimide/2,2′-diallylbisphenol A/3-allyl-5,5-dimethylhydantoin resin system

The 3-allyl-5,5-dimethylhydantoin (ADMH) was synthesized and characterized by Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance (NMR), and 13C-NMR spectroscopy. Then, the ADMH was used to modify the N, N′-(4,4′-diphenylmethane)bismaleimide (BDM)/2,2′-diallylbisphenol A (DABPA) resin to obtain the BDM/DABPA/ADMH resin system (BDA). The curing behavior was investigated by non-isothermal differential scanning calorimetry and the activation energy ([Formula: see text]) was obtained by Kissinger and Ozawa models. The thermomechanical property was measured by dynamic mechanical analysis. Analysis of the data revealed the complexity of the curing reaction, which was firstly dominated by the Ene reaction of allyl and C=C double bond at low and medium temperatures and was further governed by the Diels–Alder reaction and the anionic imide oligomerization occurred at high temperatures. The results demonstrated that 1-BDA had the best thermal and mechanical properties exhibiting excellent modification effect of ADMH.

Flame–retarded epoxy resin with high glass transition temperature cured by DOPO-containing H-benzimidazole

A halogen-free flame retardant of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-containing H-benzimidazole (DHBI) was synthesized and subsequently used as co-curing agent of 4,4′-diamino-diphenylmethane for diglycidyl ether of bisphenol-A. The structure of DHBI was characterized by Fourier transform infrared (FTIR) spectroscopy, proton, carbon 13 and phosphorus-31 nuclear magnetic resonance, and mass spectroscopy. A series of cured epoxy resins (EPs) were prepared and their flame retardancy, thermal stability, flexibility, and dielectric properties were investigated. The resulting cured EP (EP-10) with 7.45 wt% of DHBI successfully achieved UL 94 V-0 rate with limited oxygen index of 35.6% and without dropping phenomenon. Compared with the cured pristine EP (EP-00), the glass transition temperature of EP-10 was increased by 6.9°C, accompanied with an enhancement of flexible strength by 13.1 MPa and a decrement of dielectric constant by 0.3 at the testing frequency of 1 MHz.

Optimization and preparation of an allyl phenoxy-modified bismaleimide resin

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.

Preparation and properties of bismaleimide resins based on novel bismaleimide monomer containing fluorene cardo structure

Novel bismaleimide resins based on 9,9-bis[4-(4-maleimidophenoxy)phenyl]fluorene (PFBMI), 2,2′-diallyl bisphenol A (DABPA), and 4,4′-dimaleimido diphenylmethane (BDM) were prepared in this article. The thermal properties of PFBMI/DABPA in different proportions (1:0.87, 1:1, and 1:1.2) were carefully characterized using differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis. The results showed that resins had good thermal stabilities especially the one at 1:0.87. Its 10% weight loss reached 433.4°C, and the residual weight percentage (RW%) was more than 50%. In addition, PFBMI was blended into BDM/DABPA in a different ratio, and the curing characteristic, thermomechanical behavior, thermal stability, mechanical properties, and moisture absorption behavior of these blends were investigated. The results revealed that the introduction of PFBMI into BDM/DABPA did not decrease the thermal stability of the modified resins but increased the RW% at 600°C. Moreover, the impact strength of the modified resins can be significantly enhanced; when the ratio is 0.08:1, it increased by 35%. The water absorption rate also decreased with the increase in the concentration of PFBMI. PFBMI monomers play an important role on the toughness reinforcement of the BDM/DABPA resin.

Synthesis and properties of a novel high-temperature diphenyl sulfone-based phthalonitrile polymer

A novel high-temperature diphenyl sulfone-based phthalonitrile polymer is prepared from bis-[4-(3,4-dicyanophenoxy)phenyl]sulfone (BDS) monomer synthesized with high yield by a simple nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile (NPN). The structure of BDS polymer is investigated by Fourier transform infrared spectroscopy and wide-angle X-ray diffraction. Curing behavior of BDS monomer with 1,3-bis(4-aminophenoxy)benzene (APB) is recorded by differential scanning calorimetry. The properties of BDS polymer are evaluated by thermogravimetric analysis, dynamic mechanical analysis, and tensile test. The results reveal that the BDS polymer exhibits excellent thermal and thermo-oxidative stabilities, high glass temperature ( Tg = 337°C), and outstanding mechanical properties (Young’s modulus: 4.02 GPa and tensile strength: 64.16 MPa). Additionally, the BDS polymer exhibits high flame retardance and low water uptake.