Characterization of Ethylene–propylene Composites Filled with Perlite and Vermiculite Minerals: Mechanical, Barrier, and Flammability Properties

Abstract

Perlite and vermiculite are naturally occurring minerals, commonly used by industry to obtain highly thermoisolative and/or non-flammable materials. However, there has been little research into the preparation and application of rubber compounds containing these inexpensive mineral fillers. Here, we show the benefits of perlite and vermiculite minerals as fillers for ethylene-propylene rubber (EPM) composites. To obtain more uniform dispersion and improved compatibility between the minerals and the elastomer matrix, 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (AMIMTFSI) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIMTFSI) imidazolium ionic liquids (ILs) were added. The mineral fillers were found to be attractive semi-reinforcing fillers, which also act as flame retardants in the elastomer composites. Furthermore, a higher content of vermiculite mineral significantly reduced the air permeability of the composites. The incorporation of ionic liquids into the EPM-filled systems had a considerable effect on the torque increment, crosslink density, and more importantly the flammability of the studied compounds. The application of 2.5 parts per hundred parts of rubber (phr) BMIMTFSI, in particular, reduced the flammability of the EPM composite, as the maximum heat release rate (HRRmax) decreased from 189.7 kW/m2 to 170.2 kW/m2.

Expanded vermiculite-filled flexible polymer composites

“…By increasing the filler loading, more bulky foam was obtained and the amount of residual char increased parallel with the TGA results. As reported in the literature, 22,28,67,71–77 incorporation of VMT led to increase in the flame spread resistance and some important reasons were underlined as follows. As known, VMT is a natural mineral that mostly composed of SiO 2 , Al 2 O 3 , Fe 2 O 3 .…”

“…Removal of the char also made the sample vulnerable against flame. 71 While the residuals of the samples with vermiculite showed foamy morphology, SEBS showed a rigid solid morphology. By increasing the filler loading, more bulky foam was obtained and the amount of residual char increased parallel with the TGA results.…”

“…72,73 It was also reported that foamy morphology functioned as a barrier layer for delaying the spread of the flame by minimizing the air contact that also led to decrease in heat transfer. 22,28,67,71–78…”

Influence of the Silica Specific Surface Area and Ionic Liquids on the Curing Characteristics and Performance of Styrene–Butadiene Rubber Composites

“…Most elastomers are unviable for industrial applications without any reinforcing filler, since they do not meet the technological requirements for, e.g., mechanical strength, abrasion resistance, damping performance, or hardness. Therefore, in the rubber industry, many types of fillers with different characteristics and activities are used [ 1 , 2 , 3 , 4 , 5 ]. The reinforcing effect of the filler mainly depends on the size of the particles and their distribution in the elastomer matrix, as well as on the specific surface area and chemical and physical nature of the filler [ 6 ].…”

The Essential Role of 1-Butyl-3-Methylimidazolium-Based Ionic Liquids in the Development of Transparent Silica-Filled Elastomer Systems

“…Maciejewska et al [29] reported that the application of different ILs in nitrile rubber composites can lead to significant improvements in the crosslink density of vulcanizates, due to the more uniform dispersion of the filler and other components in the curing system. We observed such effects in our previous studies of ILs in different elastomer systems [28,30,31]. In the present study, significantly higher values for the crosslink density were observed in the case of NBR/BMIMAlCl 4 (8.1•10 −5 mol/cm 3 for 2.5 phr and 10.2•10 −5 mol/cm 3 for 5 phr) compared to NBR/BMIMTFSI (6.9•10 −5 mol/cm 3 for 2.5 phr and 7.2•10 −5 mol/cm 3 for 5 phr).…”