Comprehensive Analysis of the Influence of Expanded Vermiculite on the Foaming Process and Selected Properties of Composite Rigid Polyurethane Foams

Abstract

This article presents the results of research on obtaining new polyurethane (PUR) foams modified with thermally expanded vermiculite. The filler was added in amount of 3 wt.% up to 15 wt.%. The additionally applied procedure of immersion the non-organic filler in H2O2 was performed to increase the exfoliation effect of thermally treated mineral and additional oxidation the surfaces. The effect of fillers on foaming process, cell structure, thermal insulation, apparent density, compressive strength, thermal properties, and flammability are assessed. The foaming process of PUR foams modified with vermiculite was comparable for all systems, regardless of the content of the filler. A slight increase in reactivity was observed, confirmed by a faster decrease in dielectric polarization for the system with modified vermiculite by H2O2. The modification of the reference system with the vermiculite increased the content of closed cells from 76% to 91% for the foams with the highest vermiculite content. Coefficient of thermal conductivity of reference foam and foams modified with vermiculite was in the range 24–26 mW/mK. The use of vermiculite up to 15 wt.% did not influence significantly on mechanical properties and flammability, which from an economic point of view is important because it is possible to reduce the cost of materials by introducing a cheap filler without deteriorating their properties.

Effect of Liquid Glass-Modified Lignin Waste on the Flammability Properties of Biopolyurethane Foam Composites

“…However, the ignition time of LigW/LG ratio 1/1 and 1/2 particles increased up to 5 s and 6 s, respectively, which was determined by the cellular structure and thermal conductivity of the resulting foam composites. Similar observations were made by Barczewski et al [ 44 ], who studied the influence of expanded vermiculite on the fire behaviour of modified polyurethane foams.…”

Cost-effective approach for fabrication of high-quality expanded vermiculite for Alizarin red S removal from aqueous media

“…The XRD pattern was similar to previous publications on expanded vermiculite, the peaks at 2θ = 27.2° and 34.32° correspond to d-spacing of 3.3 Å, and 2.6 Å, respectively [34]. The diffraction peak at around 60 o is ascribed to the (060) plane indicating the trioctahedral type kind of the vermiculite structure [34][35][36]. Typically, vermiculite can exist in either dioctahedral or trioctahedral forms, although the trioctahedral variety is more prevalent in soils that have a similar structure to mica [37].…”

“…2a. The XRD pattern was similar to previous publications on expanded vermiculite, the peaks at 2θ = 27.2° and 34.32° correspond to d-spacing of 3.3 Å, and 2.6 Å, respectively [34]. The diffraction peak at around 60 o is ascribed to the (060) plane indicating the trioctahedral type kind of the vermiculite structure [34][35][36].…”

Impact of Different Ratios of Lignin Waste and Liquid Glass on the Performance Characteristics of Biopolyurethane Foams

“…The volumetric percentage of closed cells increased with the addition of particles, regardless of the amount of LG used for modification. However, Barczewski et al [ 35 ] showed that the incorporation of expanded vermiculite resulted in a different tendency. The thermal conductivity was higher for composite foams with the highest closed-cell content, while Członka et al [ 36 ] indicated that walnut shell filler improved the thermal conductivity of composite foams with the highest content of closed cells.…”