Cell structures, phase morphologies and impact toughness of phenolphthalein poly(ether ether ketone)/epoxy composite foams

Abstract

Thermoplastic phenolphthalein poly(ether ether ketone) (PEK‐C) /epoxy composite foams were prepared by free foaming process (Fre‐foams) and limited foaming process (Lim‐foams), respectively, and the effects of PEK‐C content and foaming methods on the cell structures, phase morphologies, and impact strength of epoxy foams were investigated. The results showed that the gas pressure in the bubbles promoted the resin curing process and polymerization‐induced phase separation process (PIPS) during the free foaming process, while the resin curing process and PIPS were highly constrained in Lim‐foams. The incorporation of PEK‐C in the Fre‐foams showed superior improvement in impact strength compared with the PEK‐C/epoxy Lim‐foams. By adding 12 wt% PEK‐C, the specific impact strength of Fre‐foams could be enhanced by 72%, and the improved specific impact strength was because the phase‐inverted structures could prevent crack initiation and propagation, and moreover the presence of PEK‐C led to significantly refine cell structure and reduce foam density. Interestingly, the impact strength of Lim‐foams was nearly independent on the PEK‐C content, it was attributed to the obviously increased cell size with increasing PEK‐C content, and also that the phase separation process was not carried out.

Computational modeling and simulation of temperature field evolution during the chemical foaming of epoxy foams

“…1 Their applications span across electronics encapsulation, 2 construction, 3 and automotive industries. 4,5 Recently, various techniques have been developed to prepare epoxy foams, such as chemical foaming, [6][7][8] physical foaming, 9,10 incorporation of hollow microspheres, 11,12 and mechanical stirring. 13,14 Among these approaches, the chemical foaming method has garnered significant attention because of its costeffectiveness and simplicity in preparation.…”

Cyanate ester resins with superior dielectric, mechanical, and flame retardance properties obtained by introducing a fluorinated hyperbranched polyaryletherketone

“…[9][10][11] PAEKs with different structures and special functions have been developed as substrates or reinforcements to prepare composite materials. 12,13 Lee et al 14 prepared polyether ether ketone type polyp-BAB/PBP to toughen epoxy resins. The fracture toughness of epoxy resins toughened with 5 wt% polyp-BAB/PBP was twice that of pure epoxy resins.…”

Effects of reactive diluent on processing, structure, and properties of epoxy foams and their sandwich composites

“…Polymer foam cores, such as epoxy and polyurethane resin, are commonly used in FSCs. 8,9 Epoxy resin is more widely used because of its good mechanical properties, slight variable shrinkage, good dimensional stability of products, simple foaming method, and other advantages. [10][11][12][13] Epoxy is a general term for compounds with two or more epoxy groups in a single molecule.…”