Preparation And Performance Of Poly (Vinyl Alcohol) Composites

Polyvinyl alcohol is a non-toxic, non-corrosive and environmentally friendlyhydrophilic polymer that can swell or dissolve in water to form a dispersion orsolution. PVA hydrophilic performance stems from hydrophilic functional groupssuch as hydroxyl in the structure, these functional groups can also be further reactedto produce a new compound having a functional group. PVA has a different degree ofpolymerization and the degree of hydrolysis, which can be controlled by the reaction.Therefore, PVA with the diverse species and performance, has become a hot field ofmaterials research. Since the PVA is strictly linear structure, and contains a lot of-OHand-H bond, which can be crosslinked to form the macromolecular network structure,therefore, PVA materials have stable chemical properties and good mechanicalproperties. In addition, PVA has good film forming property, caking property andbiological compatibility, which makes it has a wide range of usage in glue, membrane,gel, fiber and biomedical materials, and other fields.With the development of materials science, pure PVA can not meet therequirements, which requires the PVA been modified, so as to meet the requirementsfor the materials performance. In recent years, PVA composite modification hasbecome a research hotspot by using of inorganic materials, organic polymer andnatural mineral. Polyvinyl alcohol composite materials are not only important in termsof basic scientific research, but also in terms of production applications. In this paper,we use polyvinyl alcohol as a matrix, which composite with grapheme oxide,Palygorskite, potassium ferricyanide three different materials, the former twocomposite materials are characterized by FT-IR, SEM and XRD, the thermalproperties, mechanical properties and water resistance of the composite film are alsotested. The third composite is used as solid-state electrolyte of supercapacitors, theelectrochemical properties are tested. The main contents are as follows:1. The grapheme oxide is prepared by modified Hummers method, and thepolyvinyl alcohol/grapheme oxide nanocomposite film with layered structure isprepared by ultrasonic dispersion and film-casting method. The microstructures of thenanocomposite films are investigated using FTIR, TEM, SEM and XRD. The thermalstability, mechanical propertids and water-resistance of the nanocomposite films are also tested. The experimental results indicate that GO sheets are well dispersed in thePVA matrix, and crystallind structure of PVA is not affected by adding GO. Thermalstability, water-resistance and mechanical properties of the nanocomposite films areimproved by strong interaction between PVA and GO.2. Palygorskite powder with great crystal aggregation is extracted, by using themethod of physical ball mill. Therefore, one-dimensional palygorskite be obtained.Meanwhile, using polyvinyl alcohol as a matrix, PVA/palygorskite nanocompositefilms are prepared by ultrasonic dispersion and cast film method. The microstructuresof the nanocomposite films are investigated using FTIR, TEM, SEM and XRD. Thethermal stability, mechanical propertids and water-resistance of the nanocompositefilms are also tested. The experimental results indicate that nano-palygorskite isdispersed in the PVA matrix well, and crystallind structure of PVA is not affected byadding nano-palygorskite. Thermal stability, water-resistance and mechanicalproperties of the nanocomposite films are improved by strong interaction betweenPVA and nano-palygorskite.3. A solid-state supercapacitor is assembled by using alkaline polyvinyl alcoholand potassium ferricyanide as gel polymer electrolyte and activated carbons aselectrodes. Significantly, this supercapacitor with PVA-KOH-K3[Fe(CN)6] aselectrolyte and separator, which possesses flexible and wide potential window. Theelectrochemical properties of the supercapacitor are also investigated using cyclicvoltammetry, galvanostatic charge/discharge measurement, and electrochemicalimpedance spectroscopy techniques. The introduction of K3[Fe(CN)6] increases theionic conductivity of electrolyte. The specific capacitance of the supercapacitor is430.95F g-1, increasing of293.15F g-1compared to the PVA–KOH system at thesame current density. The energy density and power density of the supercapacitorreach57.94Wh kg-1and59.84kW kg-1, respectively. In addition, the supercapacitorexhibits excellent cycle-life stability, its capacitance remains higher than380F g-1after1000cycles at a current density of1A g-1. These novel flexible gel polymerelectrolytes are desirable for applications in supercapacitor devides.