Preparation and properties of melamine-formaldehyde rigid closed-cell foam toughened by ethylene glycol/carbon fiber

Abstract

Toughing melamine-formaldehyde (MF) rigid closed-cell foams were prepared by using ethylene glycol (EG) and carbon fiber (CF) as composite toughening agents. The pulverization rate, compressive strength, bending strength, cellular structure, closed-cell ratio, water absorption ratio, thermal conductivity, thermal stability, limiting oxygen index (LOI), and char yield were characterized to study the morphology, mechanical, thermal, and fire-retardant properties of as-prepared toughing MF rigid foams. The pulverization rate result showed that introduction of composite modifier can obviously improve the toughness of MF rigid foams. The cellular structure, closed-cell ratio, and water absorption results showed that the addition of EG/CF can increase the closed-cell ratio and control the cell size of MF rigid foams. The compressive strength and bending strength results showed that the incorporation of composite modifier of MF rigid foams dramatically improved the mechanical properties. The LOI, char yield, and thermal stability results showed that the toughing MF rigid foams remained more intact char skeleton with flame-retardant effect, thus reducing the fire hazards. The as-prepared toughing MF rigid foams showed the best comprehensive performance with pulverization rate of 5.21%, compressive strength of 355.3 kPa, bending strength of 0.44 MPa, closed-cell ratio of 79.1%, water absorption of 9%, thermal conductivity of 0.031 W m−1 K−1, and LOI of 39.6%. Compared with unmodified MF rigid foams, toughing rigid closed-cell MF foams possess excellent pulverization rate, compressive strength, bending strength, cellular structure, thermal insulation, and flame retardancy.

Recent Developments in Biobased Foams and Foam Composites for Construction Applications

“…PF foams possess excellent fire retardancy but lack mechanical robustness. Although foam toughness can be enhanced by adding various toughening agents such as polyethylene glycol [153][154][155][156][157][158] prepolymer [159][160][161][162][163][164], and polyvinyl alcohol [165,166], the foam loses its flame retardancy due to the flammability induced by these additives, resulting in a trade-off [130,167]. In an effort to replace highly effective halogen-based flame retardants, some studies have incorporated phosphorus containing compounds in the PF resin [168][169][170][171].…”

Preparation of a novel melamine foam structure and properties

“…Furthermore, the synthesis conditions required are harsh and therefore difficult to perform at an industrial production level. Subsequently, numerous studies on the chemical modification of melamine resins with compounds such as polyethylene glycol, 13,14 urea‐formaldehyde resin, 15 diethylene glycol, 4 and silicone 16 were reported, whereby modified melamine resins were obtained. Generally, melamine resin prepared via such a method is difficult to be stored, and the prepared foam typically possesses poor compressive strength.…”