Vinylidene chloride polymer

Yasahura A, M Morita (1988). Eormation of chlorinated aromatic hydrocarbons by thermal decomposition of vinylidene chloride polymer. Environ Sci Technol 22 646-650. 

Figure 1. Hydrogen Chloride Evolution for the Thermal Degradation of a Typical Vinylidene Chloride Polymer.

Scheme 1. The Principal Step Involved in the Thermal Degradation of Vinylidene Chloride Polymers.

The onset temperature for degradation is virtually identical for the three polymers. This would suggest that any thermal instability observed for vinylidene chloride polymers generated using peroxide initiators must arise elsewhere, perhaps from residual initiator in the finished polymer. 

Scheme 7. Structures of Butyl Ester Comonomers Incorporated Into Vinylidene Chloride Polymers.

Kirkpatrick, D. E., Hyun, K.S., and Chung, C.I., Friction and Its Effect on the Mechanical-to-Thermal Energy Conversion During Extrusion of Poly(Vinylidene Chloride), Polym. Eng. Set, 33, 1261 (1993)... 

Vinylidene Chloride Monoperoxide. When vinyli-dene chloride is stored without a polymerization inhibitor (such as tertiary butyl catechol or other phenol type inhibitors) at a temp of between -40 and +25° in the presence of air or oxygen, the 02 dissolves to form a peroxide compd of undetermined nature which is an extremely violent expl This peroxide seems to act as a polymerization catalyst because its formation is often accompanied by the pptn of a flocculent vinylidene chloride polymer. Since the peroxide is absorbed on the pptd polymer, any separation... 

Barrier properties -ofparylenes [XYLYLENE POLYMERS] (Supplement) -of PP films [OLEFIN POLYMERS - POLYPROPYLENE] (Vol 17) -ofPTFE [FLUORINE COMPOUNDS, ORGANIC - POLYTETRAFLUOROETHYLENE] (Vol 11) -of vinylidene chloride polymers [VINYLIDENE CHLORIDEMONOMERAND POLYMERS] (Vol 24)... 

Poly( vinylidene chloride) does not dissolve in most common solvents at ambient temperatures. Copolymers, particularly those of low crystallinity, are much more soluble. However, one of the outstanding characteristics of vinylidene chloride polymers is resistance to a wide range of solvents and chemical reagents. The insolubility of PVDC results less from its polarity than from its high melting temperature. It dissolves readily in a wide variety of solvents above 130°C. 

Vinylidene chloride polymers are more impermeable to a wider variety of gases and liquids than other polymers. For example, commercial copolymers are available with oxygen permeabilities of 0.03 nmol/m s-GPa. This is a consequence of the combination of high density and high crystallinity in the polymer. An increase m either tends to reduce permeability. Permeability is affected by the kind and amounts of comonomer as well as crystallinity. A more polar comonomer, e.g., an AN comonomer, increases the water-vapor transmission more than VC when other factors are constant. All VDC copolymers, are very impel meable to... 

Vinylidene chloride polymers are highly resistant to oxidation, permeation of small molecules, and biodegradation, which makes them extremely durable under most use conditions. However, these materials are thermally unstable and, when heated above about 120°C, undergo degradahve dehydrochlorination. 

Vinylidene chloride polymers have several properties that are valuable in the coatings industry excellent resistance to gas and moisture vapor transmission, good resistance to attack by solvents and by fats and oils, high strength, and the abilrtv to be heat-sealed. 

Vinylidene chloride polymers are often made in emulsion, bul usually are isolated, clned, and used as conventional resins. Stable latices have been prepared and can be used directly for coatings. The principal applications for these materials are as barrier coatings on paper products and, more recently, on plastic films,... 

Among nonmetallic materials, glass, chemical stoneware, enameled steel, acid-proof brick, carbon, graphite, and wood are resistant to iodine and its solutions under suitable conditions, but carbon and graphite may be subject to attack. Polytetrafluoroethylene withstands liquid iodine and its vapor up to 200°C although it discolors. Cloth fabrics made of Saran, a vinylidene chloride polymer, have lasted for several years when used in the filtration of iodine recovered from oil-well brines (64). 

Fig. 5. Hydrogen chloride evolution for the thermal degradation of a typical vinylidene chloride polymer.

Acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, ethyl acetate, and tetrahydrofuran are solvents for vinylidene chloride polymers used in lacquer coatings methyl ethyl ketone and tetrahydrofuran are most extensively employed. Toluene is used as a diluent for either. Lacquers prepared at 10—20 wt % polymer solids in a solvent blend of two parts ketone and one part toluene have a viscosity of 20—1000 mPa-s (=cP). Lacquers can be prepared from polymers of very high vinylidene chloride content in tetrahydrofuran—toluene mixtures and stored at room temperature. Methyl ethyl ketone lacquers must be prepared and maintained at 60—70°C or the lacquer forms a solid gel. It is critical in the manufacture of polymers for a lacquer application to maintain a fairly narrow compositional distribution in the polymer to achieve good dissolution properties. 

Vinylidene Chloride Copolymer Latex. Vinylidene chloride polymers are often made in emulsion, but usually are isolated, dried, and used as conventional resins. Stable latices have been prepared and can be used diiecdy for coatings (171—176). The principal applications for these materials are as barrier coatings on paper products and, more recently, on plastic films. The heat-seal characteristics of VDC copolymer coatings are equally valuable in many applications. They are also used as binders for paints and nonwoven fabrics (177). The use of special VDC copolymer latices for barrier laminating adhesives is growing, and the use of vinylidene chloride copolymers in flame-resistant carpet backing is well known (178—181). VDC latices can also be used to coat polyethylene terephthalate) (PET) bottles to retain carbon dioxide (182). 

Use Plasticizer-stabilizer for vinylidene chloride polymers, synthetic rubbers and cellulosic lacquers, insecticides. 

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