Polyvinyl alcohol is a white flake, flocculent or powder, solid organic compound, tasteless, soluble in water (more than 95℃), insoluble in gasoline, kerosene, vegetable oil, benzene, toluene, dichloroethane, carbon tetrachloride, acetone, ethyl acetate, methyl alcohol and ethylene glycol, and slightly soluble in dimethyl sulfoxide. PVA is a widely used water-soluble macromolecular polymer, with its performance between plastic and rubber, classified as fiber and non-fiber in applications.
When heated to about 100℃, the appearance of PVA powder will gradually change. The partially alcoholysised PVA will start to melt at about 190℃, and decompose at 200℃. The completely alcoholysised PVA will start to melt at about 230℃, and decompose at 240℃. Thermal cracking experiments show that the lower degree of polymerization, the faster reduction in weight; the higher degree of alcoholysis, the shorter decomposition time.
Used as PVC suspension polymer dispersant, polymerizable emulsifier, and in manufacturing of polyvinyl acetal, gasoline resistance pipeline, vinylon synthetic fiber, fabric treating agent, paper coating and adhesive.
Solubility：soluble in water (the higher water temperature, the higher solubility) and hardly soluble in organic solvents. The solubility of PVA varies with its alcoholysis degree and polymerization degree. The partially alcoholysised PVA with low polymerization degree dissolves rapidly, while the completely alcoholysised PVA with high polymerization degree dissolves slowly. As a general rule, the effect of the alcoholysis degree on the PVA solubility is greater than that of the polymerization degree. The PVA dissolution process is in stages: affinity wetting —》swelling —》infinite swelling —》dissolution.
PVC suspension polymer dispersant: Liquid vinyl chloride monomer, with water as the dispersion medium, will suspend in the water phase in granular or bead-like shapes for polymerization, by virtue of the stirring effect at certain temperatures after addition of the dispersant and initiator (insoluble in water but soluble in monomer). Upon completion of polymerization, white powder PVC resin can be obtained through alkali wash, steam stripping, centrifugation and drying.
Building glue: PVA can be used as putty glue and coating adhesive base material in the industry.
Textile slurry: PVA is mainly used in pure-polyester or polyester yarns, with good adhesiveness and film-forming properties.
Adhesive: In addition to glue for building, PVA can also be manufactured into adhesive for various uses by combining with other raw, chemical materials, or can be used to produce white latex as protective colloid, mainly used in paper, woods, textiles, glues for office purposes and base materials for top-grade coatings.
Fiber: Vinylon fiber is a synthetic fiber produced with the PVA material, including vinylon short fiber, vinylon long fiber, high strength and high modulus fiber, medium strength and medium modulus fiber, water-soluble fiber and other varieties.
Polyvinyl butyral (PVB): PVB film is mainly used as the intermediate film for glass. PVB laminated glass has excellent performance in safety, thermal insulation, noise control and ultraviolet isolation, and is widely used in building safety glass. High-end PVB film is used in automobile windshields, used as bullet-proof glass for aircraft, tanks and naval vessels in the military industry, and also used in solar cells and solar receivers.
Paper-making: PVA has strong adhesiveness to cellulose, good film-forming properties and high film strength. PVA is mainly used as a paper surface sizing agent, pigment adhesive and beater additive in the paper-making industry, which can increase the paper’s abrasion resistance, fold resistance, tear resistance, and improve the glossiness, smoothness and printing adaptability.
Biodegradable PVA film: Water-soluble PVA film is a new plastic product in the international market. It can be completely degraded into CO2 and H2O by use of PVA film-forming properties and water- and bio-degradation properties, which is really a green, high-tech, environmental-friendly packing material. In Europe, America and Japan, water-soluble PVA film has been widely used for packaging of various products.