Cellulose Nanocrystal/Polydimethylsiloxane hybrid membranes for air dehydration at elevated temperatures

This research study developed a dense composite membrane made of cellulose nanocrystal (CNC) and polydimethylsiloxane (PDMS) to efficiently separate water vapor from air at elevated temperatures up to 80°C. In this study a casting method was used to fabricate CNC/PDMS membranes. The water vapor permeability of the membrane samples was measured with a Payne diffusion cell (dry cup method) coupled with a Dynamic Vapor Sorption (DVS) instrument, while the nitrogen gas permeability was measured with a gas permeation cell. The results showed that the optimal CNC concentration of 2%, enhanced water vapor permeability at all temperatures up to 24.8% while increasing the selectivity slightly up to 3.1%. The membranes were characterized using AFM, FTIR, SEM, and TMA. measured the CTE of the prepared samples to study the dimensional stability as a function of temperature change. The optimized membranes showed an 8.9% lower value for CTE which results in higher thermal dimensional stability of the sample. The results have demonstrated that CNC-reinforced PDMS has potential to be used as selective membranes to remove water vapor from exhaust warm air such that the air recovers its drying capability and can be recirculated as the working medium in drying systems.