Toughened polyester matrices for advanced composites

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.

Linseed vinyl ester fatty amide toughened unsaturated polyester-bismaleimide composites

“…From Table 1 it is also evident that the incorporation of 5, 10 and 15 wt.% of bismaleimide into LVEFA-modified unsaturated polyester decreases the toughness behavior by 19, 23, 32%, respectively, due to the formation of an intercrosslinked network and rigid molecular structure. 9…”

“…Unsaturated polyester resins exhibit many desirable properties, such as high strength and modulus, excellent chemical, solvent, and salt water resistance, good thermal and electrical properties, outstanding adhesion to various substrates, and easy processability under various conditions. Liquid rubbers have been used with unsaturated polyester resin to increase the impact properties of unsaturated polyester, [4][5][6][7][8] fracture toughness and strain to failure of the neat resin have also been improved with block copolymers of carboxyl terminated acrylonitrile butadiene copolymer (CTBN), and hydroxyl-terminated acrylonitrile butadiene copolymer (HTBN) 9 , low profile additives such as poly (methylmethacrylate), poly (vinyl acetate), polypropylene glycol, [10][11][12] and polyurethanes. 13 Modification with these polymeric materials have enhanced toughness behaviour, but failed to enhance thermomechanical properties.…”

Mechanical and Thermal Properties of Hemp Fiber-Unsaturated Polyester Composites Toughened by Butyl Methacrylate

“…The UPE resins have been extensively used in fiber-reinforced composites for applications in the aerospace, automotive, marine structure, infrastructure, military facilities, and sporting goods industries (Sharmila et al 2007). However, applications of UPE resins are limited by the brittle nature of the resin due to its high degree of crosslinking and the significant shrinkage that take place during the curing process, and its poor resistance to crack propagation (Acha et al 2003).…”

Rubber modification of unsaturated polyester resin with core–shell rubber particles: Effect of shell composition

“…It was found that the compatibility and interfacial adhesion between the UP and the rubber are the crucial parameters that change the morphology and toughness of the resulting blends. In another research, Sharmila et al [22] used vinyl ester oligomer and bismaleimide as toughening agents for the UP.…”