PVC Polyvinyl Chloride

PVC is manufactured by three routes bulk (or mass), suspension, and emulsion polymerization using free radical initiators (section 1.8.1). In the bulk polymerization using liquid vinyl chloride monomer (VCM), the polymerization is usually done in two stages at 60 °C. Pre-polymerization to about 10% conversion yields a viscous suspension (PVC is insoluble in VCM) which is then added to a second horizontal reactor (together with more monomer and peroxide catalyst) with slowly rotating agitator blades. The mixture at 25% conversion becomes a powder. 

Bulk and suspension PVC is mainly used for extruded, injection and blow-moulded articles together with the addition of a plasticizer (section 1.14.2). The morphology of the PVC particle is important in order to ease plasticization with liquid additives. The emulsion produced PVC (obtained using a water-soluble initiator) is generally used as a latex (50-70% solids) for coating fabrics, paper (for wallpaper) etc. 

Because PVC decomposes at temperatures above 100 (T 173°) it cannot be melt processed without heat stabilizers and plasticizers (section 1.14.1). 

Copolymers of vinyl chloride/(3-20%) vinyl acetate are made by the suspension process. Because of the high reactivity of VCM it must be added continuously throughout the polymerization. Its main application is for gramphone records. Another useful copolymer is poly(vinyl chloride/vinyli-dene dichloride). When made into films by the bubble technique it shows low gas permeability (cling-wrap film). 

Chlorinating PVC to yield CPVC reduces the crystallinity and raises the heat distortion temperature (HDT) to 100° (cf 65° for PVC). CPVC is used for domestic hot water pipes. 

Polyvinyl chloride is a thermoplastic homopolymer of vinyl chloride monomer, with the following structure  

The melting temperature, about 212°C, and decomposition temperature of PVC are very close together, rendering unmodified PVC very difficult to process. Decomposition produces HCl, which is highly corrosive, especially in the presence of water. To reduce problems associated with decomposition, stabilizers are added to PVC octyl tins are most often used in rigid PVC for food and pharmaceutical packaging. The first indications that PVC is decomposing occur at temperatures as low as 100°C (212°F). 

Processing of PVC is carried out by conventional methods such as injection molding, extrusion, blown film, and blow molding. Additives used in PVC (as well as other plastics) must be FDA-approved if the resin is used in food contact applications. 

Flexible PVC film is often used for packaging food products, particularly fresh red meat. The oxygen permeability of PVC film is well suited to maintain the necessary oxygen requirements of the meat, to preserve its red color and appearance of freshness. PVC films also provide good toughness and resilience. PVC is also used to wrap fresh fruits and vegetables. Almost all poultry producers in the U.S. once used PVC stretch films for chilled, tray-packed poultry parts. However, multilayer barrier films have made considerable inroads in this market. PVC is also used for a variety of other food and nonfood packaging applications, as illustrated in Table 4.8. 

over the years, has been subjected to scrutiny on health and environmental grounds. One issue is the level of residual vinyl chloride monomer in the material that may migrate into food. Vinyl chloride monomer has been determined to be a carcinogen, at least under some conditions. In the polymerization process for PVC, less than 100% of the vinyl chloride monomer (VCM) is converted to polymer. This means that relatively high values of VCM may remain unreacted and trapped in the resin. To remove this residual monomer, the resin is subjected to repeated applications of vacuum. In this manner, VCM concentrations in the resin are reduced substantially. PVC packaging resins currently produced have much lower levels of residual vinyl chloride (under 10 ppb) than those used in containers in the mid-1970s when this concern first surfaced. 

Worldwide, polyvinyl chloride (PVC) is one of the most extruded polymers by volume. While environmental and health concerns has created lost market share in certain applications, PVC has made large gains in other areas, such as the replacement of wood and aluminum profiles in building construction products. Blown film extrusion is also used in the manufacture of products from PVC. Though PVC has limited thermal stability, it has good melt strength, which lends itself nicely to blown film extrusion. 

PVC is an amorphous polymer (glass transition temperature = 220 °F, 105 °C). As a result, it has good clarity. Another important characteristic is that it can be extruded either as a rigid material or as a flexible material by adding a plasticizer to the polymer. Rigid films can be metallized and punched into sequins for dressmaking applications. Flexible films are used to overwrap clothing and other textile products. 

Two other important characteristics of PVC taken advantage of in film applications are barrier properties and heat-shrinkability. Because of these attributes, PVC film finds usage in food packaging, such as candies, as well as nonfood packaging, such as shrink wrapping of auto parts. 

Pol)rvinyl chloride is the most widely used of any of fhe thermoplasts. PVC is polymerized vinyl chloride fhaf is produced from ethylene and anhydrous hydrochloric acid. The structure is  

Two types of PVC are produced, normal impact (t)rpe 1) and high impact (t5tpe 2). Type 1 is a rigid, unplasticized PVC having normal impact with optimum chemical resistance. Type 2 has optimum impact resistance and reduced chemical resistance. 

T)tpe 1 PVC (unplasticized) resists attack by most acids and strong alkalies, gasoline, kerosene, aliphatic alcohols, and hydrocarbons. It is 

PVC may be attacked by aromatics, chlorinated organic compotmds, and lacquer solvents. PVC is resistant to all normal atmospheric pollutants including weather and UV degradation. 

Refer to Table 2.35 for the compatibility of type 2 PVC with selected corrodents and Table 2.36 for type 1 PVC. Reference [1] provides a more comprehensive listing. 

Gladyshev and co-workers [1] pointed out that, during the thermo-oxidative degradation of PVC, highly conjugated systems are produced and these can be conveniently followed by electron paramagnetic resonance (EPR) and ultraviolet (UV) spectroscopy. 

Various workers [1-7] have discussed the application of electron spin resonance (ESR) and EPR to the examination of paramagnetic centres in PVC. 

PVC is known to show two-step carbonisation that is readily distinguishable by its thermogram or by its abrupt change to a tarry state at around 400 °C. In the first stage, up to 400 °C hydrochlorination is the chief reaction, and dehydrogenation does not occur unless by oxidation. 

In this study, PVC was heat-treated in most cases at 400 C and its ESR properties (e.g., growth of spin centres and saturation characteristics) studied. 

Thus it seems that the formation of spin centres is related to dehydrochlorination and oxidation. The reason for the difference between the two types of curves, in air and in a vacuum, may be that the oxidation successively causes main-chain scission 

Polyvinyl Chloride (PVQ A formulation that has worked satisfactorily in both rigid and flexible PVC is as follows (5)  

PVC resin (medium mol. wt.) tetrahydrofuran methyl ethyl ketone organic tin stabilizer dioctyl phthalate (plasticizer) methyl isobutyl ketone 

Care must be taken in handling this formulation because of the slightly toxic nature of the tetrahydrofuran. The resin solids content of this formulation is over 22%. So it is a heavy-bodied cement. 

Wang and Smith [15] developed pyrolysis followed by the GC technique for determining up to four monomer units in vinylidene chloride-vinyl chloride-(C/D) copolymers. 

The major mechanism of producing oligomers with pyrolysis can be attributed to thermal degradation. The intensity of the various oligomer peaks in a pyrolysis gas chromatogram will reflect the monomeric sequence and polymer structure when the formation of pyrolysis products is proportional to their existence in the copolymer. 

The unique phenomenon in the pyrolysis of vinylidene chloride/vinyl chloride copolymer is trimer formation. Under pyrolysis conditions, the polymer will directly undergo 

Because these chlorinated aromatics are so stable, the trimer formation pathway is the major pyrolysis pathway for the vinyl chloride/vinylidene chloride copolymer. 

Two major factors dominate the relationship between triad distribution and trimer production. The first is pyrolysis efficiency, which represents the probability/efficiency of breakdown of a specific triad configuration to produce the corresponding trimer. The second is detection efficiency, which results in variable flame ionisation detection (FID) responses for the trimers. These two factors cannot be separated in the vinylidene chloride/vinyl chloride copolymer composition and structure determination case. The relationship between trimer production and triad distribution can be expressed as  

For the flash pyrolysis of PVC, the mass balance is presented in Table 10.17. The mass fraction of the hydrogen chloride is included as it is one of the main products in the gas phase. 

In the same temperature range, the solid fraction found by Williams [8] is quite large, with a low fraction of HCl compared with the results of Scott [6], This could be explained if carbonization is not totally complete in the first case. A higher temperature, the solid fraction is reduced in favour of the gas and oil fractions. In the gas phase, the part of HCl nearly reaches its theoretical yield. According to Williams [8] the oils contain principally benzene and toluene respectively 22.1 and 9.6% by mass. 

The results of the PVC decomposition in slow pyrolysis are presented in Table 10.18. 

By the dynamic method, Miranda [38], working between 1 and 20 K/min, finds a plateau at 36% conversion. A weight loss of 64% is higher than the theoretical loss of HCl. This is explained by some benzene formation during the dehydrohalogenation step. The temperatme at which the second decomposition step occurs is higher if the heating rate increases. 

According to Miranda [38], the proportion of solid depends strongly on the heating rate (6.9-12.4% for heating rates respectively from 1 to 20 K/min). Analysis of the solid by Wilhams [16] reveals a carbon content of 90.2% with only 2.9% ash. 

Vinyl chloride has been known for over a hundred years and its polymerization to polyvinyl chloride (PVC) was achieved in 1912. Industrial-scale production of this plastic began in 1927. PVC is still the most versatile plastic. One of the reasons for this is the numerous variations made possible by the method of manufacture of the polymer, namely by copolymerization with other monomers and their processing. Thus, PVC can be thermoformed on all conventional processing machines if the slight thermal damage is taken into consideration. Machining is easy and the material can be bonded, bent, welded, printed and thermoformed. 

A distinction is drawn between bulk, suspension and emulsion PVC on the basis of different polymerization methods. 

It must be pointed out here that exact and reproducible colorations of PVC in the laboratory and in the plant present problems and can be achieved only if specified working conditions are observed and special equipment is used. 

In many cases pigment-plasticizer pastes are also used for coloring PVC. Because of the mixing or embrittlement gap in the PVC-plasticizer system, which ranges from 5 to 18% for dioctyl phthalate for example, such pastes have little or no suitability for unplasticized PVC compounds. In this concentration range, which is specific for each plasticizer, no plasticizing effect is achieved, on the contrary the additive causes embrittlement of the PVC. 

Organic pigments can be dispersed readily in plasticizers, for example with the aid of triple-roll mills. However, the throughput here is low because of the lack of smoothness of such pastes compared to other systems such as letterpress or offset inks, which is why attrition mills are better. 

If one hydrogen is replaced with chlorine in the ethylene molecule, vinyl chloride is formed. If vinyl chloride polymerizes polyvinyl chloride, known as PVC, is formed. PVC is lightweight, long lasting, and waterproof. In its rigid form, PVC is water-resistant and can be drawn out into pipes, house siding and drainpipes. It is also used in compact discs and computer casings. 

Plastic bottles made up of both high density polyethylene left and low density polyethylene right. 

the polymerization product of chlorine-substituted ethylene derivatives, is probably the most widely used plastic for process plant construction. It is available in four different types rigid, high impact, high temperature and plasticized. 

Wipe with solvent, such as methanol, low-boiling petroleum ether, MEK, toluene, or TCE 

Abrade with medium-grit (200-grit) sandpaper 

Eor maximum strength, prime with nitrile-phenolic adhesive or bond immediately 

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While with-in the mobile x-ray system, the waste in the sampler, is contained within a replaceable (and disposable) polyvinyl chloride (PVC) sleeve with a wall thickness of approximately 0.2-inches and a sealed bottom. It was anticipated that the PVC tube or sleeve would, with use, become highly contaminated with waste residues which drip of fall-off the sampler. The sleeve is coated with a conductive coating to prevent static electricity buildup . There are no sources of ignition in this sealed spare. The sampler (and waste) is coupling which includes a positive pressure gasket. This barrier is further isolated by a second barrier consisting of an epoxy coated aluminum sleeve also sealed-off from the main x-ray cabinet and PVC sleeve. There are also no potential sources of ignition in this isolated secondary space as well. 

Polyvinyl chloride Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) pipe and tubing are available in sizes 12 in and smaller for PVC and 4 in and smaller for CPVC. They have excellent resistance at room temperature to salts, ammonium hydroxide, and sulfuric, nitric, acetic, and hydrochloric acid but may be damaged by ketones, aromatics, and some chlorinated hydrocarbons. 

The important thermoplastics used commercially are polyethylene, acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), cellulose acetate butyrate (CAB), vinylidene chloride (Saran), fluorocarbons (Teflon, Halar, Kel-F, Kynar), polycarbonates, polypropylene, nylons, and acetals (Delrin). Important thermosetting plasttcs are... 

List the monomers of polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS). 

Petroleum pitch was obtained from Kureha Company, Japan (designated here as KS pitch). A second petroleum pitch was obtained from the Crowley Tar Company, U.S.A. (designated here as CRO pitch). Polyvinyl chloride (PVC) was obtained from the Aldrich Chemical Company (U.S.A.). These samples are all soft carbon precursors. 

Resins and plastics such as low-density polyethylene (LDPE), high-density polyethylene (HOPE), linear low-density polyethylene (LLDPE), polypropylene, polystyrene, and polyvinyl chloride (PVC) ... 

Bromine chloride s reactivity with metals is not as great as that of bromine however, it is comparable to chlorine. Dry BrCl is typically two orders of magnitude less reactive with metals than dry bromine. Most BrCI is less corrosive than bromine. Like chlorine, BrCl is stored and shipped in steel containers. Also, Kynar and Viton plastics and Teflon are preferred over polyvinyl chloride (PVC) when BrCl is in the liquid or vapor states. 

Polyvinyl Chloride (PVC) 1940 M-H VG G G G Extrusion, injection, rotational, slush, transfer, compression, blow mold Pipe conduit and fittings, cable insulation, downspouts, bottles, film... 

The development of electrical power made possible the electrochemical industry. Electrolysis of sodium chloride produces chlorine and either sodium hydroxide (from NaCl in solution) or metallic sodium (from NaCl fused). Sodium hydroxide has applications similar to sodium carbonate. The ad vantage of the electrolytic process is the production of chlorine which has many uses such as production of polyvinyl chloride. PVC, for plumbing, is produced in the largest quantity of any plastic. 

Vinyl chloride (1835) formed by reacting acetylene with hydrochloric acid, was polymerized a.v polyvinyl chloride (PVC) in 1912, The theory of polymerization by Staudinger in the 1920s- led to the advances that followed. The acrylate were polymerized as polymethylmethacrylate to come into production in 1927. Polystyrene was developed. similarly and concurrently. Polyethylene came into production in 1939 for use in radar and now is ubiquitous. 

Vinyl chloride is an important monomer for polyvinyl chloride (PVC). The main route for obtaining this monomer, however, is via ethylene (Chapter 7). A new approach to utilize ethane as an inexpensive chemical intermediate is to ammoxidize it to acetonitrile. The reaction takes place in presence of a cobalt-B-zeolite. 

Polyvinyl chloride (PVC) is one of the most widely used thermoplastics. It can be extruded into sheets and film and blow molded into bottles. It is used in many common items such as garden hoses, shower curtains, irrigation pipes, and paint formulations. 

The products of this electrolysis have a variety of uses. Chlorine is used to purify drinking water large quantities of it are consumed in making plastics such as polyvinyl chloride (PVC). Hydrogen, prepared in this and many other industrial processes, is used chiefly in the synthesis of ammonia (Chapter 12). Sodium hydroxide (lye), obtained on evaporation of the electrolyte, is used in processing pulp and paper, in the purification of aluminum ore, in the manufacture of glass and textiles, and for many other purposes. 

Vinyl chloride Polyvinyl chloride (PVC) Root tile, raincoats, pipe, phonograph records... 

Polysaccharide, 617,619 Polythiophene, 93 Polyunsaturated fats, 604 Polyvinyl chloride (PVC), 612-613 Positive integer, 643... 

Polyvinyl chloride (PVC) Good Yellows. Antioxidants and stabilizers... 

When water (a Newtonian liquid) is in an open-ended pipe, pressure can be applied to move it. Doubling the water pressure doubles the flow rate of the water. Water does not have a shear-thinning action. However, in a similar situation but using a plastic melt (a non-Newtonian liquid), if the pressure is doubled the melt flow may increase from 2 to 15 times, depending on the plastic used. As an example, linear low-density polyethylene (LLDPE), with a low shear-thinning action, experiences a low rate increase, which explains why it can cause more processing problems than other PEs. The higher-flow melts include polyvinyl chloride (PVC) and polystyrene (PS). 

When two polymers interact or react with each other, they are likely to provide a compatible, even a miscible, blend. Epoxidized natural rubber (ENR) interacts with chloro-sulfonated polyethylene (Hypalon) and polyvinyl chloride (PVC) forming partially miscible and miscible blends, respectively, due to the reaction between chlorosulfonic acid group and chlorine with epoxy group of ENR. Chiu et al. have studied the blends of chlorinated polyethylene (CR) with ENR at blend ratios of 75 25, 50 50, and 25 75, as well as pure rubbers using sulfur (Sg), 2-mercapto-benzothiazole, and 2-benzothiazole disulfide as vulcanizing agents [32]. They have studied Mooney viscosity, scorch... 

The ductility of GRT-polyethylene blends drastically decreases at ground rubber concentration in excess of 5%. The inclusion of hnely ground nitrile rubber from waste printing rollers into polyvinyl chloride (PVC) caused an increase in the impact properties of the thermoplastic matrix [76]. Addition of rubber powder that is physically modihed by ultrasonic treatment leads to PP-waste ethylene-propylene-diene monomer (EPDM) powder blends with improved morphology and mechanical properties [77]. 

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