| Résumé: | The widely employed technique for dehumidifying air through refrigerant cooling method
consumes an immense amount of energy. To improve energy efficiency, independent
humidity control system using desiccant has been introduced. This study focuses on
finding an alternative to the commonly used solid desiccant, silica gel, to improve the
mechanical properties, sorption capacity and recyclability. This study reports on the
synthesis of poly(vinyl alcohol-co-acrylic acid) (P(VA-AA)) via solution polymerisation
from the hydrolysis of poly(vinyl acetate-co-acrylic acid) (P(VAc-AA)). To enhance both
the mechanical and sorption properties of the copolymer, graphene oxide (GO) was
incorporated as a filler at different concentrations ranging from 0.5% to 5%. The prepared
samples were characterised by various techniques, including Fourier transform infra-red
spectroscopy (FTIR), field emission scanning electron microscope (FESEM), X-ray
diffraction analysis (XRD), thermogravimetric analysis (TGA), and differential scanning
calorimetry (DSC). The results demonstrate that the added filler was uniformly
distributed within the polymer matrix, leading to enhanced thermal properties. It was also
observed that the nanocomposite film containing 2% GO, denoted as P(VA-AA)/GO2,
showed improved mechanical characteristics with values of 4.780 MPa for tensile
strength, and 7.831 GPa for Young's modulus. The samples were also tested for their
ability to adsorb moisture from the surroundings at different relative humidity (RH) levels
and their capability to maintain optimum sorption capacity for 10 repeated cycles.
Experimental results show that P(VA-AA)/GO2 exhibited notable improvement in
sorption capacity for all RH levels. The P(VA-AA)/GO2 can adsorb 0.245 g/g water
vapour at 25 °C and 90% RH, compared to the P(VA-AA) without filler, which could
only adsorb 0.015 g/g water vapour at the same conditions. This vast difference is attributed to the larger proportion of hydrophilic functional groups in GO. This result is
also supported by the contact angle measurements, in which P(VA-AA)/GO2 has reduced
contact angles by 31% compared to its pristine copolymer that indicates its hydrophilicity.
The composite desiccant is also able to maintain its adsorption capacity at every cycle
(10 cycles).
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