The properties of silylated polyvinyl alcohol based foams reinforced by microfibrillated cellulose (MFC)

Abstract

In this study, polyvinyl alcohol (PVA) composite foam reinforced with microfibrillated cellulose (MFC) was prepared using freeze-drying process. The MFC from sugarcane bagasse (SCB) was extracted via chemical treatment assisted with ultrasonication. However, a noteworthy problem of incorporating MFC-SCB into PVA foam is that their low melting point, lacks fine interfacial adhesion and high moisture absorption. Therefore, in this study, the PVA-MFC foam was chemically silylated with Ƴ- methacryloxypropyltrimethoxysilane (MPS) and tetraethoxysilane (TEOS) to overcome the weakness of incorporating MFC-SCB into PVA foam. It was found that PVA-MFC foam with PVA molecular weight of 50 kDa, concentration of MFC-SCB suspension 2 w/v % and 20 w/v % concentration of PVA resulted the highest porosity (68 %) and lowest density (0.48 g cm-1). This PVA-MFC foam denoted as 2,20PVA-MFC. Preferred silanization parameter of 2,20PVA-MFC foam was found at 10 wt % of silane concentration and two hours of reaction time. The wetting ability and mechanical strength of the silylated 2,20PVA-MFC foam was greatly enhanced compared with unmodified 2,20PVA-MFC foam. The silane chemicals (MPS and TEOS) had been confirmed grafted on 2,20PVA-MFC foam due to presence of Si-C and Si-O-C stretching vibration in fourier transform infrared (FTIR) spectra and cloud-like coating of porous pore was observed in scanning electron microscopy (SEM) micrographs. In addition, the silylated 2,20PVA-MFC foam (MPS and TEOS) exhibit a series of desirable properties such as lower swelling ratio and high absorption capacity of solvents and oils. The characterization of 2,20PVA-MFC foam using TEOS was further investigated by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectrometer (XPS) analysis and Brunauer-Emmett-Teller (BET) specific surface area. A significant morphological difference between the unmodified and silylated 2,20PVA-MFC-TEOS foam was clearly observed through FESEM micrographs. Despite that, the XPS and BET analysis also exhibit Si 2p spectrum and low specific surface area on the silylated 2,20PVA-MFC-TEOS foam, respectively. This versatile silylated 2,20PVA-MFC foam could therefore be a promising option as a novel adsorption material for solvent and oil removal in the treatment of polluted water.