Pervaporation of dichloromethane‐cyclopentane and methylal‐cyclopentane mixtures through membranes from chloroprene rubber

Abstract

Chloroprene rubber (CR) has been commonly applied in various branches of the industry but its application in selective layers of pervaporation membranes remains overseen. To survey its applicability, we report on the pervaporation of two close‐boiling azeotrope‐forming systems of common solvents, blowing agents, adjuvants, and refrigerants, namely, dichloromethane‐cyclopentane (DCM‐CP) and methylal‐cyclopentane (ML‐CP). Vulcanizates having the form of thin films (66 ± 5 μm) have been prepared from the crystallization‐resistant (WRT) polychloroprene by using nanoparticles of ZnO and MgO. Mechanical and thermal properties have been characterized using dynamic mechanical analysis (DMA) and thermogravimetry analysis, spectral properties using ATR‐FTIR. Plasticization has been assessed by measuring DMA characteristics for the CR films exposed to vapors of the studied compounds. The CR films are preferentially permeable to DCM and ML over CP, break the respective azeotropes, and show comparable selectivity ranging from 1.1 to 1.7 for DCM‐CP and from 1.0 to 1.8 for ML‐CP. Importantly, plasticization of the CR membranes by DCM and ML enhances the selectivity and, simultaneously, the transmembrane flux. Overall, we show that membranes from CR enable selective and intensive pervaporative recovery of halogenated hydrocarbons from their mixtures with hydrocarbons, which is relevant, for instance, for the recycling of blowing agents.

Stiffening and softening of freshly prepared and aged CTA, PTMSP, and PIM‐1 films exposed to volatile compounds

“…2.5 × 0.5 cm, width × length) were analyzed using a DMA DX04T (RMI, Czechia). A previously reported self‐developed apparatus was used to evaluate the changes in mechanical properties of the films exposed to vapors of organic solvents 23,49,60 . Each film was exposed to the stream of nitrogen for at least 1 h at 40 °C prior to the measurement to remove residual volatile compounds, such as moisture.…”

“…A previously reported self-developed apparatus was used to evaluate the changes in mechanical properties of the films exposed to vapors of organic solvents. 23,49,60 Each film was exposed to the stream of nitrogen for at least 1 h at 40 C prior to the measurement to remove residual volatile compounds, such as moisture. Afterward, a continuous stream of nitrogen partially saturated with the tested vapor was conducted to the sample.…”