Abstract:Fibres are preimpregnated by solutions of mono-and bis-maleimides with comonomers. Imides alone polymerize to resins with too low energies of fracture. In the presence of Methylene dianiline or Aniline Diphenylmethylenebismaleimide reacts via Michael addition to equimolar addition products. When fibres are preimpregnated with these addition compounds alone or in combination with flame retardants, B-prepregs are obtained, which after curing show high glass temperatures and sufficient energies of fracture. 2.5 m… Show more
“…The relationship curves between ln(β/Tp2) vs. 1/Tp and lnβ vs. 1/Tp are shown in Figure 3. The values of Δ E and n are calculated as 78.17 kJ/mol and 0.91, this Δ E is equivalent to or lower than those of other modified bismaleimide resins, 33,34 indicating that the RTM bismaleimide resin under consideration is of higher reactivity.Figure 3.Plots of ln(β/Tp2) versus 1/Tp and lnβ versus 1/Tp.…”
The properties of a RTM bismaleimide resin with low viscosity and ultra-high temperature resistance were systematically investigated, including its curing kinetics and rheological properties, and the thermal and mechanical properties of its cured resins. The thermal curing kinetics was investigated by differential scanning calorimetry (DSC) method with multiple heating rates. DSC curves display a cure regime in the temperature range of 150∼300°C and the exothermic peaks shift from 194°C to 231°C with heating rate. The apparent activation energy of curing reaction is calculated as 78.2 kJ/mol. The rheological properties were studied in terms of the changes of the non-isothermal and isothermal viscosity tested using a rotary viscometer. The test results show that the RTM resin has a wide molding temperature window from 90°C to 200°C and long molding time at 110°C for 275 min with a flow viscosity less than 1000 mPas. Dual-Arrhenius model was established to predict the viscosity characteristics at different constant temperatures, showing a good agreement with the experimental data. Four curing cycles were designed to obtain cured networks with different microstructures, and the thermal and mechanical properties of the cured resins suffered from various curing cycles were characterized by dynamic mechanical analysis (DMA) and universal material testing machine. The results exhibit that the cured product has a ultra-high glass transition temperature of 373.5°C and larger flexural strength of 145.4 MPa after post-curing at 250°C for 10 h.
“…The relationship curves between ln(β/Tp2) vs. 1/Tp and lnβ vs. 1/Tp are shown in Figure 3. The values of Δ E and n are calculated as 78.17 kJ/mol and 0.91, this Δ E is equivalent to or lower than those of other modified bismaleimide resins, 33,34 indicating that the RTM bismaleimide resin under consideration is of higher reactivity.Figure 3.Plots of ln(β/Tp2) versus 1/Tp and lnβ versus 1/Tp.…”
The properties of a RTM bismaleimide resin with low viscosity and ultra-high temperature resistance were systematically investigated, including its curing kinetics and rheological properties, and the thermal and mechanical properties of its cured resins. The thermal curing kinetics was investigated by differential scanning calorimetry (DSC) method with multiple heating rates. DSC curves display a cure regime in the temperature range of 150∼300°C and the exothermic peaks shift from 194°C to 231°C with heating rate. The apparent activation energy of curing reaction is calculated as 78.2 kJ/mol. The rheological properties were studied in terms of the changes of the non-isothermal and isothermal viscosity tested using a rotary viscometer. The test results show that the RTM resin has a wide molding temperature window from 90°C to 200°C and long molding time at 110°C for 275 min with a flow viscosity less than 1000 mPas. Dual-Arrhenius model was established to predict the viscosity characteristics at different constant temperatures, showing a good agreement with the experimental data. Four curing cycles were designed to obtain cured networks with different microstructures, and the thermal and mechanical properties of the cured resins suffered from various curing cycles were characterized by dynamic mechanical analysis (DMA) and universal material testing machine. The results exhibit that the cured product has a ultra-high glass transition temperature of 373.5°C and larger flexural strength of 145.4 MPa after post-curing at 250°C for 10 h.
“…Due to its high strength and stability, advanced composite materials are widely used in various fields such as the electronics industry and aerospace. Polyimides are thermos-resistant polymers with imide groups in the main chain, which have been intensively studied since the 1960s for their excellent thermal stability and high mechanical properties, along with their super chemical resistance and electrical properties [1,2]. As a matrix of fiber reinforced plastics or composites, Bismaleimide (BMI) is a new type of thermosetting resin derived from the imide resin system in polyimide-based advanced composites, which not only retains the advantages of high-temperature resistance of polyimide resin, but also have excellent processability, corrosion resistance, low shrinkage, and low creep properties comparable to epoxy resin.…”
The low toughness of bismaleimide resin (BMI) hinders its application in the aerospace field. In order to improve the strength and toughness of BMI resin simultaneously, this study proposes to introduce perylene-dicyandiamide (P-DCD) nanosheets with an ultra-s rigid conjugated planar structure into the polymer matrix of bismaleimide resin through hydrogen bonding and cross-linking to construct modified composites. The research results showed that the modified cured composites exhibited excellent mechanical properties, with a significant increase in impact strength of 135.8%, flexural strength and flexural modulus of 87.1% and 44.6%, respectively. The thermal properties of the resin were maintained before and after modification, with the glass transition temperature (Tg) of 284.0 ˚C and decomposition temperature > 520 ˚C. Meanwhile, the strengthening and toughening mechanism of the bismaleimide-based system modified by additive P-DCD were also explored. The results showed that the functional group of dicyandiamide in nanosheets and the hydrogen bonding effect in P-DCD synergically increased the cross-linking network and compatibility between P-DCD and the matrix resin.
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