Sol Gel Mechanism

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Results and discussion Reaction mechanism of the sol-gel process Monodisperse silica NPs can be prepared by hydrolysis and condensation of alkoxysilanes in a mixture containing alcohol, water, and catalyst. The chemical reactions describing the hydrolysis and condensation of TEOS and MTES are shown in Fig. 3. As shown in this figure, TEOS can be hydrolyzed and condensed to form SiO2 colloid particles in mixture of Methanol, NH4OH and H2O after being stirred for 1 h at room temperature. Similar to the results reported by Wang et al., the obtained inorganic silica (SiO2) colloid particles have active hydroxyl groups on their surfaces. When MTES is added into the SiO2 colloid sol, the ethoxy groups of MTES can be immediately hydrolyzed, generating…show more content…
It is generally accepted that the addition of inorganic NPs into the polymeric matrix improves the polymer’s mechanical properties (Nguyen et al., 2013). In this regard, the mechanical strength of fabricated membrane was examined in terms of stress and elongation at break. Data derived from mechanical testing are shown in Table 6. It can be seen that the synthesis of inorganic NPs on the surface and cross section of the PP hollow fiber membrane has increased the membrane rigidity. Enhancement in membrane rigidity is achieved by increasing the stress and decreasing the elongation. This must be due to the original property of inorganic materials and the re-enforcement effect of incorporated NPs in the membrane matrix (Ahsani and Yegani, 2015). The TGA analysis was carried out to further confirm the formation of PP composite membrane. Fig. 11 shows the weight loss curve obtained by TGA for the pure PP membrane and the modified membrane. From TGA curve, it can be seen that the thermal decomposition of composite membrane is higher than the pure PP membrane because of the existence of inorganic NPs on the membrane surface which had a higher thermal resistance. Other researchers observed a similar behavior for the incorporation of the fluorinated silica inorganic layer on the PEI membrane (Zhang and Wang,
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