Preparation and Characterization of Sandwich Structured Materials with Interesting Insulation and Fire Resistance

Abstract

A cellular material in the form of 3-layered sandwich structure material was prepared via sole use of mechanical stirring without any use of a foaming agent, while Tween-80 was employed as a foam stabilizer via a developed in-situ mold casting. The resulting structure displayed a good appearance with no visual defects. The 3-layered composition of the sandwish structure, "nonporous resin layer-porous foam layer-nonporous resin layer", was examined in terms of the microstructure, density & density distribution, pulverization ratio, mechanical strength, insulation and flame retardant performance. It was indicated from the results that the bonding between the resin layer and foam layer was tight, while the tensile rupture always occurred in the porous layer. Also, the density of the sandwich structure material was symmetrical with "saddle" distribution, and a uniform density for any given layer. The increase in the density at the interface layer provided a good interpretation for the tensile rupture never occurred at the interface. The brittleness resistance of the developed material was significantly improved, and the pulverization ratio was sharply decreased from 9.93% to 0.31%. The material acquired a thermal conductivity and limiting oxygen index (LOI) of 0.0241 W/m ⋅ K and 29.92%, respectively, indicating potential use of such materials broadly in fields of insulation and flame retardancy.

An Investigation into the Relationship between Density and Pulverization Ratio for Tannin-Furanic Foam

“…Another option was to reconsider TF from a structural point of view and design the terminal foam product. The sandwich structure, as an innovative aspect for practical application, was successfully applied to ameliorate the defects of TF [16]. This method played an important role in reducing the pulverization ratio of TF foam as an engineering method for surface enhancement.…”

“…Presumably based on the original data, this phenomenon could be explained by the fact that, the thicker the cell walls of the foam, the stronger the cross-linking between the substances, which gives rise to a lower value of pulverization ratio. The thicker cell walls provided a more stable cross-linked structure that was less susceptible to external damage [16]. For TGF-6, this could be explained by its large pores and thin cell walls leading to its high pulverization ratio.…”