Polyvinylchloride films

The tapes are usually produced from polythene or polyvinylchloride films of 25 /im to 0-5 mm in thickness and the inner surface is coated with an adhesive, frequently rubber-based. The adhesive is usually between 25 and 100/im thick. 

Shapoval, G.S. Kontsur, Y.V. Electrochemical initiation of surface dehydrohalogenation of polyvinylchloride films. J. Macrom. Sci. Pure Appl. Chem. 1995, A32, 49-54. 

Umemura, J., Takenaka, T., Hagashi, S., Gotoh, R. Infrared dichroism and orientation of plasticizers in stretched polyvinylchloride films. Bull. Inst. Chem. Res. Kyoto Univ. 46, 228 (1968). 

Although it is well known that when polyvinylchloride (PVC) is irradiated with UV light, discoloration, dehydrochlorination, decomposition and crosslinking occur, few ESR studies on PVC irradiated with UV light have been reported. Nishijima et al. (86) observed an ESR spectrum after UV irradiation of a polyvinylchloride film with light of 185 nm at —196° C under vacuum. The sample was heated at various temperatures for 10 min after UV irradiation at —196° C. The changes in a spectral shape, radical concentration, A Hmsl and A H are shown in Figs. 9 and 10. It is apparent that a broad component decays out at about —100° C and a narrow component at about 80° C. The former could be attributed to some kinds of alkyl radicals and the latter to... 

The choice of fluorescent probe depends on a variety of factors. It has already been pointed out that what is determined directly is information which characterises the distribution of orientations of the fluorescent molecules. The ideal experiment would be one in which the polymer molecules themselves contained fluorescent groups. Stein has considered the theory of the fluorescence method specifically for a uniaxially oriented fluorescent rubber but no experiments to study orientation have been reported for such a system. Nishijima et al have, however, made some qualitative observations on the polarisation of the fluorescent light from polyvinylchloride films which had been first stretched and then irradiated with light of wavelength 185 nm to produce fluorescent polyene segments. 

A thermal desorption capillary gas chromatographic method has been use to analyze volatiles from clingfilms (289). This procedure was able to differentiate 14 brands of polyvinylchloride film and 7 brands of polyethylene film. The forensic examination of clingfilms is often requested, and this gas chromatographic procedure offers an alternative to physical methods for comparing control and recovered clingfilms. 

While the polyvinyl acetate-based emulsions have multiple applications (office glues, wood glues, packaging industry, etc.), the acrylic emulsions are used mainly for the production of autoadhesive films and tapes or for other labels (see PSAs part) their main value therefore lies in the large variety of formulations accessible (using variable composition copolymers) and in the good tolerance they demonstrate toward the plasticizers present in certain substrates (bonding of polyvinylchloride films for example). 

Vina, S. Z., Mugrldge, A., Garcia, M. A., Ferreyra, R. M., Martino, M. N., Chaves, A. R. Zaritzky, N. E. (2007). Effects of polyvinylchloride films and edible starch coatings on quality aspects of refrigerated Brussels sprouts. Food Chemistry, 103, 5, 701-709. 

Although they have an endless variety of properties, polymers can be divided into three general categories, based on their form and resistance to stretching. These are plastics, fibers, and elastomers. Plastics differ in form from fibers whereas plastics exist as blocks or sheets, fibers have been drawn into long threads. Unlike plastics or fibers, elastomers can be stretched without breaking. Polyethylene packaging films and polyvinylchloride (PVC) pipe are examples of plastics. Orion carpets are made from polymer fibers, and mbber bands are elastomers. Some polymers, such as Nylon, can be formed into both plastics and fibers. 

Many membranes are made from a film of polyvinylchloride (PVC) in which one or many ion transporters (ionic or neutral) are inserted. Some 40 chelates are used in about a dozen selective membranes (Fig. 18.5). Electrodes used for CIO4 and BF4 are of this type. 

Examples are the sulfonating of polyethylene film with chloro-sulfonic acid (60) the sulfonating of sheets of phenolformaldehyde resin (77) the treatment of a film consisting of polystyrene and polyvinylchloride with concentrated sulfuric acid (4) the sulfonating of films consisting of aliphatic vinylpolymers with chlorosulfonic acid (125) the sulfonating of copolymers of a monovinyl- and a polyvinyl compound (30). Also are used copolymers of aromatic monovinyl-compounds and linear aliphatic polyene hydrocarbons (3) copolymers of an unsaturated aromatic compound and an unsaturated aliphatic compound (76), and of reaction products of poly olefines and partially polymerized styrene (173). 

Polyvinylchloride (PVC) is a hard, amorphous polymer which softens at about 85 °C. Also in PVC rubbers are sometimes added in order to improve the impact strength. The main applications of PVC are pipes, gutters, front panels of buildings, cables, bottles, floor tiles. A much softer and more flexible material is obtained by blending with plasticizers soft or plasticized PVC is being used in artificial leather, tubes and hoses, footwear, films, etc. 

Ion selective membranes are the active, chemically selective component of many potentiometric ion sensors (7). They have been most successfully used with solution contacts on both sides of the membrane, and have been found to perform less satisfactorily when a solid state contact is made to one face. One approach that has been used to improve the lifetime of solid state devices coated with membranes has been to improve the adhesion of the film on the solid substrate (2-5). However, our results with this approach for plasticized polyvinylchloride (PVC) based membranes suggested it is important to understand the basic phenomena occurring inside these membranes in terms of solvent uptake, ion transport and membrane stress (4,6). We have previously reported on the design of an optical instrument that allows the concentration profiles inside PVC based ion sensitive membranes to be determined (7). In that study it was shown that water uptake occurs in two steps. A more detailed study of water transport has been undertaken since water is believed to play an important role in such membranes, but its exact function is poorly understood, and the quantitative data available on water in PVC membranes is not in good agreement (8-10). One key problem is to develop an understanding of the role of water uptake in polymer swelling and internal stress, since these factors appear to be related to the rapid failure of membranes on solid substrates. 

Besides the general insulating properties of insulating materials, chemical and thermal stability is required and excellent film-forming properties and methods for patterning the insulating layer. Therefore, the most common polymers (e.g. polyethylene, polypropylene, polyvinylchloride etc.) have not yet been used as gate-dielectric layers. 

Daun, H., Gilbert, S.G., 1977, Migration of plasticizers from polyvinylchloride packaging films to meat. JoumalofFoodScience 42 (2) 561-562. 

The kinetics of combination of radical pairs formed by quenching of the triplet excited state of B by 2,4,6-trimethylphenol (HR) in films of rigid and plasticized polyvinylchloride (PVC) were studied by the method of laser flash photolysis by Levin et al. At high concentrations of the phenol quencher ( 15 wt%), most of the triplet excited state of the ketone is quenched and the formation and disappearance of the ketyl and phenoxyl radicals can be followed from changes in their characteristic transient absorptions at 540 and 390 nm, respectively. 

The major use of vinyl chloride (also known as vinyl chloride monomer, VCM) is in the production of the ubiquitous plastic, PVC or polyvinylchloride, which began to be used in the 1940s. This polymer is used in a wide variety of products ranging from cling film, bottles, car components, pipes, electrical insulation, and window frames. Unfortunately, vinyl chloride, which is used to make the plastic, is a hazardous chemical. For this reason and because PVC is an organochlorine compound, it has received a bad press. It has important properties, however, such as flexibility, toughness, and durability, that make it an extremely useful and versatile material. 

Most polymer membrane ISEs are prepared by dissolving an ionophore in a polyvinylchloride (PVC) membrane. A large variety of plasticisers are used to increase the dielectric constant of the PVC and improve its hydrophilicity. Some membranes have complexes of the ions to be sensed to increase membrane conductivity, such as potassium tetraphenylborate in K -selective membranes. There is an extensive literature on the arcane arts of polymer membranes for electrodes with dissolved ionophores and a good review of this is given by Professor Ronald Armstrong in Section 3.7 of Gabor Harsanyi s book. Polymer films in sensor applications [14]. 

Liteanu and Hopirtean described a polyvinylchloride-tricresyl phosphate electrode as being responsive to Ag, H, ngj" ", Na", and Although the electrodes composed of polymeric films directly on metals are attractive from the viewpoint of simplicity, the mechanism of their function remains to be elucidated, and the scope of their applications remains to be studied. 

A number of manufactured products comprising thermoplastics (polyethylene, polyvinylchloride, polyamides,. ..) or elastomers (natural rubber, nitrile rubber, ethylene propylene rubber, silicones) are processed by cross-linking to improve their performances in insulated electric wires and cables, multilayered films for cooking pouches, shape memory tubes, pressure resistant water pipes, expandable foams, automotive parts exposed to motor... 

Many commercial selective electrodes include a membrane made of a plasticized polyvinylchloride (PVC) or polysiloxane film in which are disseminated various ion-carriers, ionic or neutral (Figure 19.5). Around 40 chelate molecules are used for around 10 common ions. Electrodes for CLO, BF, NH, Ca + are of this type. 

The backing material and release liner can be fabricated from a variety of materials including polyvinylchloride, polyethylene, polypropylene, ethylene-vinyl acetate and aluminium foil. The most important property of these materials is that they are impervious to both drug and formulation excipients. The most useful backing materials conform with the skin and provide a balanced resistance to transepidermal water loss, which will allow some hydration of the stratum corneum, yet maintain a healthy subpatch environment. The release liners are usually films or coated papers and must separate easily from the adhesive layer without lifting off any of the pressure-sensitive adhesive. Silicone release coatings are used with acrylate and rubber-based adhesive systems, and fluorocarbon coatings with silicone adhesives. 

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