No abstract

An intercrosslinked network of hybrid bismaleimide (BMI) modified vinyl ester oligomer-unsaturated polyester matrix systems have been developed. Vinyl ester oligomer (VEO) was used as a toughening agent for unsaturated polyester resin and was added in 2, 4, and 6% (by wt). Benzoyl peroxide was used as curing agent. The VEO-toughened unsaturated polyester matrix systems were further modified with 5, 10, and 15% (by wt) of bismaleimide. Bismaleimides modified vinyl ester-unsaturated polyester matrices were characterized by mechanical (tensile strength, flexural strength, tensile modulus, flexural modulus, and impact strength), thermal [differential scanning calorimetry (DSC), thermogravimetic analysis (TGA), heat deflection temperature analysis (HDT)] and morphological studies [scanning electron microscope (SEM)] and water absorption. Data obtained from mechanical studies indicated that the introduction of VEO into unsaturated polyester resin improves the fracture toughness. The introduction of BMI into VEO incorporated unsaturated polyester resin enhanced both thermal and mechanical behavior. The scanning electron micrographs of fractured surfaces of VEO-modified unsaturated polyester systems and BMI modified vinyl ester-unsaturated polyester matrices illustrate the presence of homogeneous morphology.

Organophilic montmorillonite clay — unsaturated polyester (UP) and vinyl ester oligomer (VEO) — unsaturated polyester nanocomposites were prepared and the formation of nanocomposites was evaluated by X-ray diffraction (XRD), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The VEO was prepared by reacting commercially available epoxy resin LY556 and acrylic acid and was used as a toughening agent for unsaturated polyester resin. Organoclay-filled hybrid VEO—UP matrices, developed in the form of castings, were characterized for their thermal and mechanical properties. Dynamic mechanical measurements indicated the presence of higher crosslink density for the clay-filled systems than unfilled systems. X-ray diffraction analysis infers the intercalation of the polymer molecules between the clay layers which in turn restricts the mobility of polymer in the vicinity of clay layers. A shift in Tg towards lower temperature was observed for nanocomposites. Significant improvement in the mechanical properties was also observed in the case of nanocomposites when compared with neat resin matrix.

An intercrosslinked network of hybrid bismaleimide-modified vinyl ester oligomer-unsaturated polyester matrix systems were developed. Vinyl ester oligomer was used as a toughening agent for unsaturated polyester resin and was added in 10, 20 and 30% (by weight). Benzoyl peroxide was used as curing agent. The vinyl ester oligomer-toughened unsaturated polyester matrix systems were further modified with 5, 10 and 15% (by weight) of bismaleimide. Bismaleimide-modified vinyl esterunsaturated polyester matrices were characterized by mechanical (tensile strength, flexural strength, tensile modulus, flexural modulus and impact strength), thermal [differential scanning calorimetry (DSC) thermogravimetic analysis (TGA) and heat deflection temperature analysis (HDT)] and morphological studies [scanning electron microscope (SEM)] and water absorption. Data obtained from mechanical and thermal studies indicated that the introduction of vinyl ester oligomer into unsaturated polyester resin improved the fracture toughness with marginal reduction in the values of heat deflection temperature and glass transition temperature. The introduction of bismaleimide into vinyl ester oligomer-incorporated unsaturated polyester resin enhanced both thermal and mechanical behavior. The SEM micrographs of fractured surfaces of vinyl ester oligomer modified unsaturated polyester systems and BMI modified vinyl ester-unsaturated polyester matrices illustrate the presence of heterogeneous morphology.