Polyvinyl discoloration

Physical effects caused by polyethylene glycol bases include softening and liquefaction in mixtures with phenol, tannic acid, and salicylic acid. Discoloration of sulfonamides and dithranol can also occur and sorbitol may be precipitated from mixtures. Plastics, such as polyethylene, phenolformaldehyde, polyvinyl chloride, and cellulose-ester membranes (in filters) may be softened or dissolved by polyethylene glycols. Migration of polyethylene glycol can occur from tablet film coatings, leading to interaction with core components. 

Plastic solid, d 1.406 n 1.54. Stabilizers are necessary to prevent discoloration from exposure to light or heat. Solvents for unmodified polyvinyl chloride of high mol wt cyclohexanone, methyl cyclohexanone, dimethyl formamide, nitrobenzene, tetrahydrofuran, isophorone, mesityl oxide. Solvents for lower polymers dipropyl ketone, methyl amyl ketone, methyl isobutyl ketone, acetonylacetone, methyl ethyl ketone, dioxane, methylene chloride. 

USE An ultraviolet light absorber for stabilizing plastics and other organic materials against discoloration and deterioration. Effective in protecting polyesters, chlorinated polyesters, polystyrene, polyvinyls, polypropylene, alkyds, cellulose acetate, ethyl cellulose, acrylates, dyes, synthetic and natural fibers, waxes, detergent solns. cosmetic formulations. Ref Dunn, Fogg, J. Appl. Polymer Sci 2, 367 (1959). 

Polyvinyl chloride Tubing, drip chanrbers Injection molding extrusion a Discolors... 

Viral transformation of Syrian hamster embryo cells has also been found to be facilitated by trivalent antimony compounds (Fowler and Goering 1991). In workers at antimony smelters, an orange-red to yellowish brown discoloration of the tooth surface ( antimony teeth ) has been observed (Bencze 1994). In 1989, attention was drawn to the possible role of antimony in the sudden infant death syndrome (SIDS) (Richardson 1990). Here, it was postulated that antimony, which was present as a fire retardant in polyvinyl cot mattresses, might be converted by certain molds into tri-... 

ISO. 105. Plastics Determination of the thermal stability of polyvinyl chloride, related chlorine-containing homopolymers and copolymers and their compounds Discoloration method. 1990. 

Polyvinyl alcohol powder is first washed with cold water to remove impurities such as alkali and sodium acetate, which may cause discoloration of the fiber in the heat treatment, and then dissolved in water under heating with direct steam. In most cases, PVA with a degree of polymerization of 1200 to 1800 is used the concentration is usually from 14 to 16% and is controlled by the measurement of the viscosity. Table 4.22 shows some examples of the viscosity of the spinning solutions measured mainly at 96°C. It is necessary that the temperature of the spinning solution is kept at least above 70°C [109]. 

Polyvinyl chloride (PVC) (1933) n. Poly (vinyl chloride), poly(l-chloro-ethylene). A vinyl polymer which is similar to polyethylene, but on every other carbon in the backbone chain, one of the hydrogen atoms is replaced with a chlorine atom. It is produced by the free radical polymerization of vinyl chloride. A white, water-insoluble, thermoplastic resin, derived by the polymerization of vinyl chloride. A hard and tough plastic solid. Stabilizers are necessary to prevent discoloration from exposure to light and heat. Used for plastics and coatings. Commonly known as vinyl. Abbreviation is PVC See image). 

Polyvinyl Chloride A synthetic resin used in the binders of coatings. Tends to discolor under exposure to ultraviolet radiation. Commonly called "vinyl."... 

Initially, degradation of polyvinyl chloride leads to a discoloration of the polymer as double bonds form along the backbone of the polymer. The delocalized electrons, along regions of seven or more adjacent double bonds, create colors such as tan, yellow, and pink. The deeper the color is, the greater the extent of degradation. Severe d radation lowers the tensile and impact strength of the polymer. 

Biocides are required when animal or vegetable substances or their derivatives (starches, casein and other proteins, nut shell flours, sugar, and cellulosic resins) are incorporated into polyvinyl acetate homo- or copolymer emulsion adhesives. Growing microorganisms digest these substances and can generate foul odors, discolor the adhesive, lower its viscosity, and weaken the bond. 

BIOMET 14 Antimicrobial Compound is a new odorless preservative which provides effective control of gram negative microorganisms when used as an additive to flexible polyvinyl chloride systems. In addition, BIOMET 14 Antimicrobial Compound provides outstanding protection for PVC against mildew and from discoloration due to microbial action even under the most severe conditions of soil burial. The broad spectrum antimicrobial properties provided by the addition of BIOMET 14 Antimicrobial Compound to vinyl film has received approval for effectiveness and safety from the Environmental Protection Agency. 

Polyvinyl chloride (PVC). At 150°C, the polymer discolors and liberates chlorine. The reaction is autocatalytic and occurs as follows ... 

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