Plasticizer from PVC

SFE can be used to extract compounds from various polymers, such as poly (vinyl chloride) (PVC). As an example, 644 mg PVC pieces are packed into an 

Berger, T. A., Packed Column SFC, The Royal Society of Chemistry, Cambridge, UK, 1995. 

and Berger C. (Eds), Supercritical Fluid Chromatography with Packed Columns Techniques and Applications, Marcel Dekker, New York, 1998. 

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A polyethylene fishing box has absorbed plasticizer from PVC lures, as seen in the furthest right compartment, and formed polyethylene fossils over a 20-year period. 

It is important to limit contact between liquid water (including that from condensation) and plastics, because some plastics have the ability to absorb moisture, swell and fail. Water acts as a plasticizer for many of the early plastics, notably casein, and can displace plasticizer from PVC (Shashoua, 2001). Polyamides, which include nylon, are the most hygroscopic polymers in common use, containing up to 3 per cent moisture by weight under ambient conditions. Cellulose acetate and poly (methyl methacrylate) contain 0.8 per cent, PVC contains 0.4 per cent and polystyrene 0.1 per cent moisture by weight at ambient... 

Some of the above assumptions ate correct and some ate false or misleading. Let s discuss these assumptions and illustrate them with experimental data. Figure 7.5 shows diffusion rates of plasticizer from PVC samples having different concerttrations of plasti-... 

To perform as an adhesive the formulation does not require plasticizer but it is known from prior art that the migration of plasticizer from PVC will affect adhesion. Properties can be modified if plasticizer is added during compounding and its addition at this stage will limit its migration from PVC. 

Figure 13.8. Migration of plasticizer from PVC into sunflower oil at 40°C. DOP - di-(2-ethylhexyl) phtha-late, TOM - tri-(2-ethylhexyl)trimellitate. [Adapted, by permission, from Hamdani M Feigenbaum A, Food Additives Contaminants, 13, No.6, Aug/...

Figure 13.8 shows dependence of the ntigration rate of the plasticizer from PVC into sunflower oil on the chemical structure of the plasticizer. The rate of ntigration depends on the plasticizer and the food simulant. For example, DOP had a very similar rate of ntigration into three tested simulants (sunflower oil, isooctane, and ethanol). Migration of TOM into sunflower oil was shown already to be faster than DOP but it is still slower than its ntigration into isooctane. Compatibihties of plasticizer, extractant, and matrix polymer affect the rate of ntigration. 

Figure 21.5. Process of recovery of plasticizer from PVC full-scale installation. 1 reactor, 2 burner, 3 hot-gas line, 4 feed line, 5 discharge line, 6 discharge line, 7 condenser, 8 condenser outlet line, 9 condensate pump, 10 line, 11 line, 12 heat exchanger, 13 line, 14 offgas line, 15 branch line, 16 branch line, 17 circulating-gas line, 18 circulating-gas compressor, 19 branch line. [Adapted from Lyding Q Pille M, von Plessen H, Semel J, US Patent 5,464,876.]...

Coltro L, Pitta JB, da Costa PA, Perez F, de Araujo MA VA, Rodrigues R. Migration of conventional and new plasticizers from PVC films into food simulants a comparative study. Food Control 2014 44 118-129. 

Table 25. TLC and TFG quantities for ester plasticizers from PVC-compounds with thermofractography (weight 0.5-1 mg, temperature region 50-300 °C respect. 150-400 °C, heating rate 4 °C/min, slide speed 0.28 cm/min, carrier gas 10 ml N2/min)... 

A fume hood is constructed in the manner shown in figure 6. Strike drew the frame as being made of lumber but it can be made of rebar or, preferably, from PVC pipes and joints so that it can be assembled and disassembled with ease. The frame is enclosed with plastic drop cloths or any semiclear plastic sheeting. The front face of the hood is halfway covered with plastic while the bottom half is exposed to allow one to move objects in or out and to manipulate things. On top of the chamber is attached some clothes dryer duct or some such crap which is led to a leaf blower or blower motor. The exhaust from the blower is led away to the outside. 

The role of specific interactions in the plasticization of PVC has been proposed from work on specific interactions of esters in solvents (eg, hydrogenated chlorocarbons) (13), work on blends of polyesters with PVC (14—19), and work on plasticized PVC itself (20—23). Modes of iateraction between the carbonyl functionaHty of the plasticizer ester or polyester were proposed, mostly on the basis of results from Fourier transform infrared spectroscopy (ftir). Shifts in the absorption frequency of the carbonyl group of the plasticizer ester to lower wave number, indicative of a reduction in polarity (ie, some iateraction between this functionaHty and the polymer) have been reported (20—22). Work performed with dibutyl phthalate (22) suggests an optimum concentration at which such iateractions are maximized. Spectral shifts are in the range 3—8 cm . Similar shifts have also been reported in blends of PVC with polyesters (14—20), again showing a concentration dependence of the shift to lower wave number of the ester carbonyl absorption frequency. 

Fig. 2. Volatile loss of plasticizers from flexible PVC (BSS 35) where M represents Cg [...

Plasticizer can also be extracted from PVC by a range of solvents including water. The aggressiveness of a particular solvent depends on its molecular size and its compatibiUty with both the plasticizer and PVC. Water extracts plasticizer very slowly, oils are slightly mote aggressive, and low molecular weight solvents are the most aggressive. 

Fig. 4. SmaH-angle x-ray scattering pattern from PVC plasticized with 20 parts per hundred resin of dioctyl phthalate (18).

In some cases, plasticization of a PSA may be detrimental to its performance. A well-known example is the deterioration of the performance of an adhesive applied to plasticized PVC. Migration of the plasticizer from the flexible vinyl into the PSA often softens the adhesive to the point where it fails cohesively from the vinyl, leaving sticky residue behind during removal of the adhesive-coated article from the substrate. One way to address this detrimental effect of plasticizer migration is to formulate an already plasticized PSA, perhaps because a better balance exists between the plasticizer in the PVC substrate and the PSA in contact with it [101]. 

Vinyl chloride zero 0.002 Increased risk of cancer Leaching from PVC pipes discharge from plastic factories... 

Produced from PVC compounds containing plasticizers such as dioctyl phthalate, this is a flexible sheeting suitable for lining tanks made from steel and concrete. The maximum temperature at which this lining can be used is 60°C. 

This is a method for making hollow articles using liquid plastics, particularly PVC plastisols. A shell-like mould is heated to a pre-determined temperature (typically 130°C for plastisols) and the liquid is then poured into the mould to completely fill it. A period of time is allowed to elapse until the required thickness of plastic gels. The excess liquid is then poured out and the plastic skin remaining in the mould is cured in an oven. The moulding is then taken from the mould. 

In the meantime another development had decisively altered the outset situation plastics had been discovered and synthesized, among them also some acid-stable ones such as phenol-formaldehyde resin or poly(vinyl chloride) (PVC). These opened up new possibilities cellulose papers could be impregnated with phenol-formaldehyde resin solution and thus rendered sufficiently acid-stable, and sintered sheets from PVC powder were developed. Independent separators producers were founded, combining knowledge of the chemical industry with experience of the battery industry and thus accelerating the development process. 

Competition, at each stage in the plastics industry, is in their raw materials. Many monomers can be made from alternate raw materials such as polyvinyl chloride that may begin with either ethylene or acetylene. Most plastic products may be made from a variety of plastics such as pipe that may be extruded from PVC, polyethylene, ABS, and so on. 

The circulation pump should be a centrifugal type with a plastic or PVC impellor, or cast iron with adequate corrosion inhibitor. The acid tank, hoses, and other equipment should be connected to and from the boiler using suitable connection points. This usually is the bottom BD connection (with the valve removed) and the open manhole as the top point. 

The BP Chemicals polymer cracking process is based at Grangemouth in Scotland and uses mixed plastics as the raw material. The reactor uses a fluidised bed which operates at 500 °C in the absence of air, and under these conditions the plastics crack thermally to yield hydrocarbons. These vaporize and are carried away from the bed with the fluidising gas. Solid impurities such as metals from PVC stabilisers accumulate in the bed or are carried away in the hot gas to be captured by a cyclone further along in the plant. PVC decomposes to HCl and this is neutralized on a solid lime absorbent to yield CaCl2 which is disposed of in landfill. The purified gas is cooled to condense most of the hydrocarbon which can be employed as commercially useful distillate feedstock. The light hydrocarbons which are less easy to condense are compressed, reheated and recycled as fluidising gas. 

The flexibility of some plastics can be improved by the addition of small molecules called plasticizers. For example, pure PVC turns brittle and cracks too easily to make useful flexible plastic products. With an added plasticizer, however, PVC can be used to make seat covers for automobiles, raincoats, garden hoses, and other flexible plastic objects. Plasticizers must be liquids that mix readily with the pol Tner. In addition, they must have low volatility so that they do not escape rapidly from the plastic. Dioctylphthalate is a liquid plasticizer that is formed by condensing two alcohol molecules with one molecule of phthalic acid, as illustrated in Figure 13-10. 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

Applications Although Soxtec combines the best qualities of reflux and Soxhlet extractions up to now fairly little evidence has been reported concerning the efficacy of this system for polymer and rubber analysis. Nevertheless, it appears that oligomers and other reaction residues, softeners, antioxidants (e.g. BHT) and several other additives used to modify polymers are easily extracted from PVC, PP, PE, PS, rubber and many other polymeric materials. Also, some leading international plastic, rubber and packaging companies have made Soxtec an integral part of their quality control routines. Some application examples where Soxtec has proved successful are [148] ... 

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