Preparation and characterization of bismaleimide‐modified bisphenol dicyanate epoxy matrices

Abstract

An intercrosslinked network of epoxy matrix systems modified by cyanate ester (CE) and bismaleimide (BMI) was developed. Epoxy systems modified with 4%, 8%, and 12% (by weight) cyanate ester were made by using epoxy resin and cyanate ester, with diaminodiphenylmethane as the curing agent. The reaction between the cyanate ester and the epoxy resin during the cure process of cyanate ester-modified epoxy systems was studied using Fourier transform infrared spectroscopy. The cyanate ester-toughened epoxy systems were further modified with 4%, 8%, and 12% (by weight) bismaleimide (N,NЈ-bismaleimido-4,4Ј-diphenylmethane). BMI-CE-Epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis, and heat deflection temperature analysis. The matrices, in the form of castings, were characterized for their mechanical properties such as tensile strength, flexural strength, and unnotched Izod impact test as per ASTM methods. Mechanical studies indicated that the introduction of cyanate ester into epoxy resin improved the toughness and flexural strength, with a reduction in tensile strength and glass-transition temperature, whereas the incorporation of bismaleimide into epoxy resin influenced the mechanical and thermal properties according to its percentage content. However, the introduction of both cyanate ester and bismaleimide influenced the mechanical properties according to their percentage content. DSC thermograms of cyanate ester-modified epoxy and BMI-modified epoxy showed unimodal reaction exotherms. The thermal degradation temperature and heat distortion temperature of the cured BMI-modified epoxy and CE-epoxy systems increased with increasing bismaleimide content.

Synthesis and properties of a liquid oligomeric cyanate ester resin

“…Even though most commercial CEs possess good flammability and high temperature properties, they are far too brittle to be widely used in structural applications. Many additives have been used to strengthen the resulting CE thermoset including epoxies [3,11,12], polyesters [13] and bismalimides [2,[12][13][14] with varying success. Co-curing the CEs with these polymers can result in non-miscibility, which has both desired and undesired effects on the physical and thermal properties of the polymeric matrix [15,16].…”

Influence of cyanate content on the morphology and properties of epoxy resins with phenolphthalein poly(ether ketone)

“…This may be attributed to the change of the network structure in the blends with the increase of cyanate content. 23 Fracture toughness is the resistance of a material toward crack initiation and propagation, and it is often expressed as K IC and G IC . As seen in Table III, Figure 6 Dynamic mechanical properties of (a) A, B, and C sample and (b) A-10, B-10, and C-10 sample.…”

Cyanate Esters

“…For instance, monomers that allow ready co-condensation with bismaleimide resins have recently been prepared. Furthermore, cyanate ester systems containing both epoxy and BMI resins such as bismaleimide-modified bisphenol dicyanate epoxy matrices have also been studied [84]. Other cyanate ester monomers have especially been developed for tailored composites such as, for instance, cyanate estermodified epoxy resin/glass fiber composites [4].…”