High Temperature Epoxy Foam: Optimization of Process Parameters

Abstract

For many years, reduction of fuel consumption has been a major aim in terms of both costs and environmental concerns. One option is to reduce the weight of fuel consumers. For this purpose, the use of a lightweight material based on rigid foams is a relevant choice. This paper deals with a new high temperature epoxy expanded material as substitution of phenolic resin, classified as potentially mutagenic by European directive Reach. The optimization of thermoset foam depends on two major parameters, the reticulation process and the expansion of the foaming agent. Controlling these two phenomena can lead to a fully expanded and cured material. The rheological behavior of epoxy resin is studied and gel time is determined at various temperatures. The expansion of foaming agent is investigated by thermomechanical analysis. Results are correlated and compared with samples foamed in the same temperature conditions. The ideal foaming/gelation temperature is then determined. The second part of this research concerns the optimization of curing cycle of a high temperature trifunctional epoxy resin. A two-step curing cycle was defined by considering the influence of different curing schedules on the glass transition temperature of the material. The final foamed material has a glass transition temperature of 270˝C.

Recent Trends of Foaming in Polymer Processing: A Review

“…Their results indicated that the PLA/PBSA foams reveal increased crystallinity and storage modulus as compared to their physically foamed counterparts. Gazzani et al [99] prepared a high-temperature epoxy foam. Table 1 shows the density of epoxy foam samples as a function of temperature.…”

Effect of Resin and Blocked/Unblocked Hardener Mixture on the Production of Epoxy Foams with CO2 Blocked Hardener in Batch Foaming Process

“…The addition of short fibers to a foaming epoxy system was also found to lead to more homogeneous cell morphology, next to an increase of mechanical performance [10]. Alternatively, syntactic foams, where several types of hollow particles or foam particles with a defined size are mixed into the resin hardener system, are used for weight reduction and cushioning purposes [11,12,13,14].…”

Thermosetting polyester foams by infiltration in soluble preforms

“…3 The active amine groups of a commercially available curing agent for epoxy resin are blocked by CO 2 to obtain ammonium carbamate, which can be decomposed again by heating above 100 C. However, typical problems of reactive systems have to be solved, above all it is necessary to find the ideal combination between gelation and foaming. 1 In order to solve this kind of problems, syntactic foams have been developed. Bubbles are not produced by foaming but by mixing the liquid resin with hollow microspheres made of glass 4 or polymer.…”

“…Apart from the case of solid state foaming, 10 all the other contributes refer to epoxy systems. [1][2][3][4][5][6][7][8][9] UP resins are very difficult to foam because of the low roomtemperature viscosity (lower than epoxies) and the fast polymerization kinetics. Recently, Zhang et al have evaluated urea-activated 4,4 0 -oxibis-(benzenesulfonyl hydrazide) OBSH as foaming agent to produce UP foams.…”

“…Controlling these two phenomena can lead to a fully expanded and cured material. 1 The goal is not only obtaining rigid foams but tailoring their structure and morphology without losing homogeneity also on large-size parts. Important results have been recently achieved for epoxy systems.…”