Polyvinylidene chloride

CH2 CCl2- Colourless liquid, b.p. 32°C, manufactured by the dehydrochlorination of trichloroethane. In the presence of light and air, it decomposes with the evolution of HCI, phosgene, and methanal and deposition of some polyvinylidene chloride. Consequently it must be stored away from light and in the presence of dissolved inhibitors (such as phenols and amines). Under the influence of... 

Saran Liners Saran (Dow Chemical Co.) polyvinylidene chloride hners have excellent resistance to hydrochloric acid. Maximum temperature is 80°C (175°F). 

Certain copolymers of this type have been found to have excellent gas barrier properties, with the dry polymer having an oxygen permeability only about 1/lOth that of polyvinylidene chloride. Unsurprisingly, the copolymer has a high moisture absorption and a high moisture vapour transmission rate. Where the material is swollen by water, gas permeability is also higher. 

The storage capacity of an ANG storage system is always greater than its delivered capacity, usually by about fifteen percent. For some carbons, however, it can be as high as thirty percent because of the large amount of methane which is held by the adsorbent at less than one bar, (0.1 MPa). Carbons which are very microporous, such as polyvinylidene chloride (PVDC) carbons, tend to have very steep initial slopes to their methane isotherm, and as much as thirty percent of their overall uptake occurs at less than 0.1 MPa. These carbons have a high storage capacity but a much lower deliverable VfV. 

PVC, polythene and PTFE if moist gas is used Stainless steel, copper, nickel. Monel, brass, aluminium for dry gas <200°C. Borosilicate glass for low pressures. For moist gas, copper and polyvinylidene chloride plastics Monel and nickel Monel and nickel Most common metals so long as gas is dry... 

Polyvinylidene chloride, polyethylene, Kel-E PTEE graphite and silicone hydrocarbon lubricants... 

Polyvinylidene Chloride 1940 H VG VG VG VG Same as PVC Auto seatcovers, film, bristles, pipe and pipe linings, paperboard coatings... 

SAN (styrene acrylonitrile) Polyvinyl chloride Plasticized Unplasticized Polyvinylidene chloride Styrene copolymer (SMA) Crystal Impact... 

PVDC polyvinylidene chloride S-N stress-number of cycles... 

Cellophane is an old and respected packaging material which has been improved over the years. The two general types are coated with nitrocellulose (N/C) and polyvinylidene chloride (PVDC), respectively. Nitrocellulose-coated cellophane is moisture proof and useful for packaging dry products. It does not exclude oxygen or moisture completely, but for noncritical products it is entirely satisfactory. Baked goods are often packaged in this breathing type film. It is often used for cookies, candies, and rolls because its lack of taste and odor makes it very compatible with these products. 

These opposing tendencies may defeat the purpose of the fractional precipitation process. The fractional precipitation of crystalline polymers such as nitrocellulose, cellulose acetate, high-melting polyamides, and polyvinylidene chloride consequently is notoriously inefficient, unless conditions are so chosen as to avoid the separation of the polymer in semicrystalline form. Intermediate fractions removed in the course of fractional precipitation may even exceed in molecular weight those removed earlier. Separation by fractional extraction should be more appropriate for crystalline polymers inasmuch as both equilibrium solubility and rate of solution favor dissolution of the components of lowest molecular weight remaining in the sample. 

RCF itself is not a good barrier, nor can it be heat-sealed. Barrier and heat-sealing are conferred by coatings of nitrocellulose or polyvinylidene chloride on one or both sides. RCF has poor dimensional stability due to moisture loss or gain. Its principal use is in laminates and over wrapping. 

MIR techniques have simplified obtaining infrared spectra of many materials important in packaging. These include rubber, plastics, laminations, and components of these materials that find use in pumps, sample packages, and devices. The combination of MIR and computerized pattern recognition techniques can be used for differentiating and classification of flexible packaging polymers such as polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), acrylonitrile (Barex), and CTFE (Aclar) [22]. 

Most common metals Most common metals Most common metals Most common metals. Polyvinylidene chloride, polyethylene, Kel-F PTFE graphite and silicone vacuum grease Copper or stainless steel Most common metals for dry gas. Stainless steel, titanium and nickel for moist gas... 

R.A. Wessling, Polyvinylidene Chloride , Gordon and Breach, New York, (1977). 

Widespread chlorine-containing polymers would include, 1) stable molding material for practical use such as polyvinyl chloride (PVC), polyvinylidene chloride and poly(epichlorohydrin)(PECH) and, 2) reactive polymers capable to introduce additional functional groups via their active chlorines such as chloromethyl polystyrene, poly (3-chloroethyl vinyl-ether) and poly (vinyl chloroacetate). While the latter, especially the chloromethyl polystyrene, has been widely used recently for the synthesis of variety of functional polymers, we should like to talk in this article about the chemical modification of the former, mainly of PVC and PECH, which was developed in our laboratory. 

Polyvinylidene chloride is produced by polymerization of vinylidene dichloride, as shown in Figure 4.38. The chlorine content can be as high as 73% versus 57% for PVCs. 

Figure 4.38. Vinylidene dichloride, polyvinylidene chloride formulae...

Poly Vinyl ACetate Poly Vinyl ALcohol PolyVinyl Butyrate Poly Vinyl Chloride PolyVinyliDene Chloride Chlorinated PVC Unplasticized PVC... 

In principle, molecular sieve carbons (MSC) can be achieved by the pyrolysis of thermosetting polymers such as polyvinylidene chloride, polyfurfuryl alcohol, cellulose, cellulose triacetate, polyacrylonitrile and phenol formaldehyde (Koresh 1980). An example is given by Trimm and Cooper (1970,1973) for the preparation of MSC (mixed with metallic compounds) for catalyst systems. A mixture of furfuryl alcohol, platinum oxide and formaldehyde was heated to 40°C and additional formaldehyde was added to ensure the... 

Vinyl chloride polymers and copolymers are often referred to as vinyl resins. PVC is the most important member of the vinyl resin family, which includes polyvinyl acetate (PVAC), polyvinyl alcohol (PVA), polyvinylidene chloride (PVdC) and polyvinyl acetal. Almost always the term PVC includes polymers of VCM as well as copolymers that are mostly VCM. 

Lebedev, B.V., Rabinovich, LB., and Budarina, V.A. Heat capacity of vinyl chloride, polyvinyl chloride and polyvinylidene chloride in the region of 60-300°K, Polymer Sci., USSR 9A 545-552, 1967. 

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