Poly vinyl chloride

Vinyl chloride polymers and copolymers are called vinyl resins. Common comonomers for vinyl chloride are 

Poly(vinyl chloride) is usually used with a plasticizer to make it softer. 

Poly(vinyl chloride) (PVC) is essentially a glassy (non-crystalline) polymer like PS. It is, however, tougher and when pigmented it can be used out-of-doors in exterior cladding, window frames, etc. where it is commonly designated UP VC ( unplasticised PVC ). This is a remarkably durable material in view of the known thermal- and photo-instability of PVC and this is achieved by the addition of substantial quantities of stabilisers (Chapter 3). The present trend is to incorporate fight stable impact modifiers based on saturated polyacrylates to increase toughness in the outdoor environment. 

PVC degrades rapidly in heat and fight unless it is effectively stabilised. The most obvious effect of degradation is discolouration initially yellowing but ultimately blackening. It is widely used in roof-lights and the formation of brown discolouration is the initial indication that the useful properties of the plastic (particularly impact resistance) are also deteriorating. Nevertheless, even transparent PVC can be made relatively durable to the outdoor environment by the use of or- 

Poly(vinyl chloride) is used in industry on a very large scale in many applications, such as rigid plastics, plastisols, and surface coatings. The monomer, vinyl chloride, can be prepared from acetylene  

The reaction is exothermic and requires cooling to maintain the temperature between 100-108 °C. The monomer can also be prepared from ethylene  

The reaction of dehydrochlorination is carried out at elevated pressure of about 3 atmospheres. 

Free-radical polymerization of vinyl chloride was studied extensively. For reactions that are carried out in bulk the following observations were made  

The polymer is insoluble in the monomer and precipitates out during the polymerization. 

The polymerization rate accelerates from the start of the reaction. Vinyl chloride is a relatively unreactive monomer. The main sites of initiation occur in the continuous monomer phase. 

The use of poly(vinyl chloride) in outdoor applications continues to grow. Much effort has gone into elucidating the mechanism of photodecomposition of poly(vinyl chloride), but many questions are still outstanding. While the realistic state of the polymer for laboratory studies is in the form of films, several reports have appeared describing investigations of photodegradation of dilute solutions of the polymer and under such conditions participation of the solvent must be seriously considered. The 

Tagawa and W. Schnabel, Makromol. Chem., Rapid Commun., 1980, I, 345. 

Lu Vinh, Bratislava lUPAC hU. Conf. Modif. Polymers, 1979, 1, 164. 

Wandelt and M. Kryszewski, X App/. Polym. ScL.Appl. Polym. Symp., 1979, 35,361. 

The vinyl family of polymers consists of poly(vinyl chloride), poly(vinylidene chloride), poly(vinyl acetate), and their copolymers and derived polymers. 

Most poly(vinyl chloride) (PVC) is commercially produced by suspension polymerization [Brydson, 1999 Endo, 2002 Saeki and Emura, 2002 Tomell, 1988]. Bulk and emulsion 

05 MPa, corresponding to about 90% conversion, excess monomer is vented off to be recycled. Removal of residual monomer typically involves passing the reaction mixture through a countercurrent of steam. The reaction mixture is then cooled, and the polymer separated, dried in hot air at about 100°C, sieved to remove any oversized particles, and stored. Typical number-average molecular weights for commercial PVC are in the range 30,000-80,000. 

Poly(vinyl chloride) is a very tough and rigid material with extensive applications. Its range of utilization is significantly expanded by plasticization, which converts rigid PVC, 

Trade names for PVC include Carina, Corvic, Darvic, Geon, Koroseal, Marvinol, Nipeon, Opalon, and Vygen. The generic term vinyl is often used for PVC products. 

The stabilization of poly(vinyl chloride) against light has been reviewed by Wirth and Andreas. Detailed mechanistic studies have indicated the importance of peroxides in the process of photo-oxidation. It was suggested that protection could be successfully achieved by exclusion of radiation of A 380 nm. E.s.r. examination of irradiated samples demonstrated the intervention of peroxides in the mechanisms with the ultimate formation of carbonyl groups which caused chain scission by Norrish cleavage. Photo-oxidation of samples of poly(vinyl chloride) modified by incorporation of acrylonitrile-butadiene-styrene, methyl methacrylate-butadiene-styrene, and methyl methacrylate-acrylonitrile-butadiene-styrene copolymers has been investigated. Discolouration was accelerated by the presence of the modifiers. Thermal pre-treatment accelerated photo-induced decomposition. Mechanical properties were also examined, and scanning electron microscopy showed surface defects due to decomposition of the modifier.  

measurements on irradiated poly(vinyI acetate) indicated that scission of the acetate group occurred to form methyl and acyl radicals.  

Poly(vmyl chloride) (PVC), the second widely used resin in the world (after polyethylene) is made by the polymerization of vinyl chloride monomer (VCM). In theory the chemical structure of the polymer is simple, consisting of the same structure as for polyethylene with one hydrogen in every other —CH2— group being replaced by a chlorine atom 

However, as the repeat unit is asymmetrical because of the presence of only a single chlorine atom, two types of linkages, head to tail and head to head, are possible  

PVC resin can also be made into a versatile soft pliable rubbery material by incorporating plasticizers such as organic phthalates into the compound. Plasticized PVC (also referred to as pPVC) is used widely as packaging film, roofing membranes, belting, hoses, and cable covering. With pPVC, calendering is 

PVC can be made by either bulk polymerization, suspension polymerization, or emulsion polymerization of the VCM. Most of the resin (over 90%) is now made by free-radical-initiated suspension polymerization of VCM. The reactor used for emulsion polymerization of the monomer is also about the same as that for suspension polymerization except that stripping is usually carried out under vacuum. Polymerization of VCM is an exothermic reaction (+410 cal/g) and removal of heat from the system is an important consideration in large-scale manufacture. Controlling the temperature of the reaction is important as it dictates the average molecular weight and the polydispersity of the resin product. This is relatively easier to achieve in suspension polymerization compared to bulk polymerization processes because the former is carried out in a water medium. 

In suspension polymerization the vinyl chloride monomer is dispersed in water using a protective colloid or a surfactant to control the final particle size (usually between 130 and 165 xm) and a monomer-soluble initiator (usually an azo compounds or a peroxide) is used. Gelatin, soaps, glycols, and pentaerythritol or their mixtures can be used as dispersing agents in the reaction mixture. The polymerization is usually carried out in a glass-lined reactor with controlled agitation, at a 

In 1959, Miller (1959a,fc) reported that radiation polymerization of a plasticized PVC containing a divinyl monomer could be used to crosslink PVC effectively without seriously affecting thermal stability. Three monomers were used poly(ethylene glycol dimethacrylate) (PEGDMA), ethylene glycol 

All these results may well be expected, but would be of no practical interest unless the thermal stability is improved, or at least riot adversely affected. Miller observed that as long as the total dose did not exceed about 1 Mrad, the discoloration on aging at 150 C characteristic of irradiated PVC was suppressed by incorporation of the divinyl monomer before irradiation. The enhanced stability was attributed to the ability of the added monomer to scavenge propagating free radicals that would otherwise facilitate dehydrochlorination. 

Other monomers have been used. Koozu et al (1963) studied the effects of monomers, including diallyl phthalate, and ethylene glycol dimethacrylate (EGDM). Gladstone et al. (1971) used monomers such as triallyl phosphate, acenaphthalene, and crotonic acid. Trimethylolpropane trimethacrylate has been reported to give a tough, heat-resistant PVC after irradiation (White and Mann, 1967). 

Of these monomers, EDMA appeared to be quite ineffective, even though it is isomeric with EGDMA discussion of EDMA is therefore omitted. 

A more detailed study of thermal behavior using both differential thermal (DTA) and thermogravimetric (TGA) analysis gave results that indicate a different aspect of thermal stability (Table 7.4). In ordinary PVC, HCl is eliminated at about 300 C, with depolymerization at about 450-460 C. The latter endotherm was found to be unchanged by the presence of monomer, stabilizer, or plasticizer or by irradiation. However, the dehydrochlorination endotherm (Thci) was quite sensitive to all these factors. The addition of plasticizer and stabilizer alone raised irradiation of such controls had no further effect. In the presence of polyfunctional monomer. 

Establishment of the detailed microstructure of PVC has attracted considerable interest. This has been spurred by the desire to rationalize the poor thermal stability of the polymer (Chapter 1). Many reviews have appeared on the chemical microstruclure of PVC and the mechanisms of defect group formation.56 60 

The presence of 1,2-dichloroethyl end groups and branch structures is likely to confuse attempts to determine head-to-head linkages by chemical methods (e.g. iodometric titration68). 

Propagation reactions involving the fluoro-olefins, vinyl fluoride (VF)6Q 7 vinylidene fluoride (VF2)69 7 74 and trifluoroethylene (VF3),75 show relatively poor rcgiospccificity. This poor specificity is also seen in additions of small 

The fraction of head-to-head linkages in the poly(fluoro-olefms) increases in the series PVF2 PVF PVF3 (Tabic 4.2). This can be rationalized in terms of the propensity of electrophilic radicals to add preferentially to the more electron rich end of monomers (i.e, that with the lowest number of fluorines). This trend is also seen in the reactions of trifluoromethyl radicals wilh the fluoro-olefins (see 2.3). 

The proportion of head-lo-head linkages in fluoro-olefin polymers also depends on the polymerization temperature6 ) 70 72 7j(T able 4.2). 

The photodegradation and photo-oxidative degradation of poly(vinyl chloride) and its copolymers and blends have been the subjects of many publications (Table 3.11) and reviews [309, 553,1172,1522,1668,1812,1815,2050,2051]. 

When poly(vinyl chloride) is exposed to UV irradiation it turns yellow and subsequently a deep red-brown colour. This discoloration occurs rapidly, due to the formation of conjugated polyene structures. Simultaneously, large 

Low density polyethylene Polyisobutylene Poly(ethylene-co-vinyl acetate) 

Poly(methyl methacrylate-co-butadiene-co-styrene) and poly(methyl methacrylate-co-acrylonitrile-co-butadiene-co-styrene) Poly(vinyl chloride-co-carbon monoxide) Poly(vinyl chloride-co-vinyl acetate) 

Poly(vinyl chloride-co-vinyl bromide) Poly(vinyl chloride-co-vinylidene chloride) Poly(vinyl chloride-co-acetylene derivatives) Poly(vinyl chloride-co-methyl vinyl ketone) 

Important processing methods extrusion, plastisol coating, thermoforming, calendering, blow molding, rotational molding, injection molding 

Typical fillers calcium carbonate, clay, talc, silica, antimony trioxide, aluminum hydroxide, magnesium hydroxide, carbon fiber, aluminum fiber, titanium dioxide, carbon black, sand, wood fiber 

Typical concentration range calcium carbonate - 20-30 wt% (rigid) 30-40 wt% (flexible), talc 5-25 wt%, antimony trioxide - 3-6 wt%, aluminum hydroxide, magnesium hydroxide - 20-40 wt%, sand 40-60 wt% 

Auxiliary agents lubricants, dispersing agents, compatibilizers (chlorinated polyethylene), aciylic impact modifier to improve impact with talc  

Special methods of incorporation dry blending including preparation of initial premix, compounding and pelletization 

The microstructure of PVC has been the subject of numerous studies (Sections 

PVC formulations can be, by virtue of both the range of functional additives used to cover a wide spread of applications and the variety of each type, the most complex, difficult yet challenging plastics to analyse. Nevertheless most additive levels are macro-scale, yielding adequate separated materials for a variety of tests. Many procedures exist for the determination of various additives in PVC by solvent extraction followed by an instrumental technique such 

An MO analysis reveals a larger electron delocalization in systems with multiple bonds. In contrast to saturated compounds, remote molecular orbitals (other than the MOs of the adjacent bonds) have appreciable contributions of 1 ppm. 

The results for the unsaturated systems PBD and PIP are less easily assessed than for aPP, PE, and PIB. The simulation results are partly in good agreement with experiment, and partly defective. Especially for the unsaturated carbons, large deviations from experimental data are found. To identify the origin of the difficulties (correlation effects , force field ), and for a final decision on the validity of the simulation method for this class of systems, additional investigations will be necessary. 

Poly(vinyl chloride) (PVC) is a simple example of a polymer system that contains a hetero atom in addition to carbon and hydrogen (Fig. 7) it can be thus checked whether the method for the ab initio spectral simulation is reliable beyond hydrocarbons. 

The PVC sample chosen as an experimental reference has a calorimetric glass transition temperature of Tg = 356 K and was purchased from Polyscience. The share of racemic diads was determined by solution -NMR 

Remarkably, atactic PVC can exhibit substantial crystallinity [114, 115]. In our sample, crystallinity was checked by wide-angle X-ray scattering (WAXS) and found to be low ( 15%). 

Moreover it was observed that a plastisol with optimum thermal stability could be produced by holding PVC at 145 C for 10 min and using a range of plasticiser concentrations between 50 and 70 phr [a.387]. A comparison between the apparent activation energies of the thermal 

Polyamides are intrinsically hygroscopic because of the polar nature of their chains, which makes them moisture-sensitive materials, and hence chemically unstable towards hydrolytic conditions. Prior to processing steps, polyamide composites need to be dried in order 

The recovery of e-caprolactam from waste PA-6 realises the high value of PA-6 and has therefore the potential to be economically competitive with the traditional synthesis processes significant positive environmental impact should also be mentioned. A presently applied recycling process is the Zimmer AG process, which performs the depolymerisation of PA-6 with the help of steam and liquid catalysts such as phosphoric acid [a.l7]. This process can be applied only for non-mixed PA-6 materials. A disadvantage of this process is the high yield of salts and traces of phosphoric acid in the recovered E-caprolactam, which is a drawback for the production of fibres. 

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ETHYLENE We discussed ethylene production in an earlier boxed essay (Section 5 1) where it was pointed out that the output of the U S petrochemi cal industry exceeds 5 x 10 ° Ib/year Approximately 90% of this material is used for the preparation of four compounds (polyethylene ethylene oxide vinyl chloride and styrene) with polymerization to poly ethylene accounting for half the total Both vinyl chloride and styrene are polymerized to give poly(vinyl chloride) and polystyrene respectively (see Table 6 5) Ethylene oxide is a starting material for the preparation of ethylene glycol for use as an an tifreeze in automobile radiators and in the produc tion of polyester fibers (see the boxed essay Condensation Polymers Polyamides and Polyesters in Chapter 20)... 

Poly(vinyl chloride) (PVC) has re placed leather in many of its appli cations PVC tubes and pipes are often used in place of copper... 

Acrylic-poly(vinyl chloride) alloy Melamine phenolic... 

Properties Poly(methyl methacrylate) Cast sheet Impact- modified Heat- resistant Alkyd, molded Acrylic poly(vinyl chloride) alloy ... 

Polyolefin Polyester Block copolymers of styrene and butadiene or styrene and isoprene Block copolymers of styrene and ethylene or styrene and butylene Poly(vinyl chloride) and poly(vinyl acetate) ... 

Poly(vinyl chloride) as previously discussed in Sec. 10.3, Formulas and Key Properties of Plastic Materials, has the following structures ... 

This experiment describes a simple gravimetric procedure for determining the %w/w Cl in samples of poly(vinyl chloride). 

Saito described a quantitative spectrophotometric procedure for iron based on a solid-phase extraction using bathophenanthroline in a poly(vinyl chloride) membrane. ... 

Figure 9.17 Plot of log [i ]M versus retention volume for various polymers, showing how different systems are represented by a single calibration curve when data are represented in this manner. The polymers used include linear and branched polystyrene, poly(methyl methacrylate), poly(vinyl chloride), poly(phenyl siloxane), polybutadiene, and branched, block, and graft copolymers of styrene and methyl methacrylate. [From Z. Grubisec, P. Rempp, and H. Benoit, Polym. Lett. 5 753 (1967), used with permission of Wiley.]...

Other Plastics. A relatively small amount of poly(vinyl chloride) goes into packagiag appHcations and appears in municipal soHd waste (25). 

Another widely used overlay adhesive is the contact type. These specialized adhesives, in the same group as mbber cement, may be of the solvent-base or water-base types. They are often used to bond overlays such as wood veneer, vinyl (poly(vinyl chloride)) films, or high pressure laminates such as countertop overlays. 

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