Plasticisers from PVC

Some typical applications in SFE of polymer/additive analysis are illustrated below. Hunt et al. [333] found that supercritical extraction of DIOP and Topanol CA from ground PVC increased with temperature up to 90 °C at 45 MPa, then levelled off, presumably as solubility became the limiting factor. The extraction of DOP and DBP plasticisers from PVC by scC02 at 52 MPa increased from 50 to 80 °C, when extraction was almost complete in 25 min [336]. At 70 °C the amount extracted increased from 79 to 95 % for pressures from 22 to 60 MPa. SFE has the potential to shorten extraction times for traces (<20ppm) of additives (DBP and DOP) in flexible PVC formulations with similar or even better extraction efficiencies compared with traditional LSE techniques [384]. Marin et al. [336] have used off-line SFE-GC to determine the detection limits for DBP and DOP in flexible PVC. The method developed was compared with Soxhlet liquid extraction. At such low additive concentrations a maximum efficiency in the extractive process and an adequate separative system are needed to avoid interferences with other components that are present at high concentrations in the PVC formulations, such as DINP. Results obtained... 

MAE has also been used for the extraction of adipate plasticisers from PVC [464]. The efficiency of MAE depends on the kind of solvent, the temperature achieved and the heating time. The final temperature reached depends on the microwave power, number of vessels and irradiation time. Higher recovery values than SEE were reported for both phthalate and adipate. Other reports on microwave-assisted solvent extraction have appeared [465-467]. 

In this short article it is reported that the successful validation of a Dutch method to measure the migration of plasticisers from PVC toys and child-care items means that a European Commission ban onphthalates is now less... 

Contamination arising from the extraction of plasticisers from PVC pipelines. 

Diethyl ether is a favoured solvent for removing additives from this polymer. It has been used to extract stabilisers, lubricants and plasticisers from PVC. Figure 2.3 shows a scheme involving ether extraction for the separation of additives from PVC [4-6, 9-10]. 

The extraction of plasticisers from PVC compositions must involve diffusion processes, and the rate of extraction should depend, to some extent, on the initial plasticiser concentration. This was found to be true for the extraction of Mesamoll by ether [18]. Compositions made by ICI, Corvic D65/1, lead stearate (0.1%), and Mesamoll (10-50%) were extracted with ether for 1-8 hours, and the plasticiser contents m (% w/w), at times t (hours), were calculated from the weights of the extracts. Figure 2.4 shows the curves obtained by plotting log m/mf) against t, for different values of m, the initial plasticiser content. In every case, except when = 10%, there is initially a very rapid loss of plasticiser, followed by a period when m/m decreases exponentially. When m/m = 10%, the rate of decrease of m/m is very small at all stages of the extraction. 

Robertson and Rowley [18] studied the extraction of plasticisers from PVC using different solvents prior to analysis by IR spectroscopy. 

VI. 1 j paration and Identification of Plasticisers from PVC VI.1.1 I reUminaiy Remarks... 

Feigenbaum et al. [54] have reported poor repeatability ( 12%) for extraction of plasticisers from PVC by means of dissolution (THF or CH2CI2)/... 

Bergner and Berg [8] also carried out early work on the migration of citric acid and phthalate plasticisers from PVC and cellulose acetate. 

The results of the study on the migration of plasticiser from PVC films into different depths of HB 307 layers are given in Table 6.1. The extent of migration of DEHP phthalate in 10 days at 40 C increased markedly with increasing plasticiser content and the concentration of DEHP in the simulant layers reached relatively high values. 

There are cases where stress cracking can occur due to the migration of a less volatile liquid (e.g., a plasticiser). An example of such a case is the stress cracking of ABS due to the migration of plasticiser from PVC, and this can be approached by the detection of phthalate in the ABS matrix by solvent extraction and then analysis of the extract using HPLC. 

From Table 5.7 it will be seen that plasticisers for PVC such as the octyl phthalates, tritolyl phosphate and dioctyl sebacate have solubility parameters within 1 cgs unit of that of the polymer. Dimethyl phthalate and the paraffinic oils which are not PVC plasticisers fall outside the range. It will be noted that tritolyl phosphate which gels the most rapidly with PVC has the closest solubility parameter to the polymer. The sebacates which gel more slowly but give products which are flexible at lower temperatures than corresponding formulations from tritolyl phosphate have a lower solubility parameter. It is, however, likely that any difference in the effects of phthalate, phosphate and sebacate plasticisers in... 

Irganox 1010 could be extracted from PP in 18min, using propan-2-ol-cyclohexane (97.5 2.5). For plasticiser extraction from PVC, optimum conditions were hexane-ethyl acetate (60 40) at 170 °C, giving effectively complete extractions after 13 min. For nylon, the optimum conditions were hexane-ethanol (60 40) at 170 °C, and extractions from ground material were 95 % complete after 16 min, including warm-up time. Irganox 1330 was used as an internal standard in PP, n -C1() in... 

For direct determination of plasticisers in PVC the sample was dissolved in THF, and phthalate or phosphate plasticisers were measured from absorbance at 240 and 275 nm or 257, 262 and 268 nm, respectively... 

Applications Most plasticisers can be removed almost quantitatively from PVC by Soxhlet extraction or direct refluxing with diethyl ether for several hours. With the dissolution (THF)/reprecipitation (n-hexane) method, PVC compounds can be isolated. However, reliable results are also obtained by using a short cut in which a PVC compound (0.3g) is dissolved in THF (lOg), insoluble material is allowed to settle and then the THF solution including PVC is injected on to the GC column [12]. Although direct gas chromatographic analysis... 

The most common plasticisers for PVC are phthalate esters prepared from aliphatic C8 alcohols. For high temperature applications higher molecular weight esters are used, e.g., from mellitic acid, which are resistant to volatilisation and are used for PVC interiors in cars (to prevent fogging of windscreens). 

This item very briefly sums up a recently-published report from EUCOMED (the European medical device industry trade association) on the use of ethylhexyl phthalate (DEHP) as a plasticiser in PVC medical products, and the risks associated therewith. 

The environmental impact of PVC is discussed with reference to the toxicity of vinyl chloride, plasticisers and heavy metal stabilisers, the formation of dioxins and acid rain resulting from the incineration of PVC waste, and plasticiser migration from PVC products. A brief examination is also made of the recyclability of PVC. 18 refs. 

TG-MS is an ideal technique for identifying residual volatiles in polymers. The detection of residual volatiles (and of other impurities) can often yield clues as to manufacturing processes. In many cases, such as in the determination of highly volatile materials, of residual solvents or plasticisers, use of TG-MS is requested. Specifically, there are reports on the entrapment of curing volatiles in bismaleimide laminates [145] and elastomers [48], on the detection of a curing agent (dicumylperoxide) in EPDM rubbers and of bromine flame retardants in electronic waste [50], of plasticisers such as bambuterol hydrochloride [142] or TPP and diethylterephthalate in cellulose acetate [143], on solvent extraction and formaldehyde loss in phenolic resins [164], and on the evolution of toxic compounds from PVC and polyurethane foams [146]. 

Pilot plant production of PVC resins began in Germany in 1931 followed by the USA in 1933. The beginning of PVC as a technically useful product stemmed from the patent disclosures of Semon of the BF Goodrich Company and Reid of Carbide and Carbon Chemicals in 1933/34. It was discovered that PVC became a flexible material that resembled rubber or leather when it was heated in the presence of a high boiling liquid. This led to the use of phthalate esters as plasticisers for PVC giving a material that was processable at acceptable melt temperatures into products which were permanently soft and flexible. 

THEORETICAL STUDY OF THE KINETICS OF LOSS OF PLASTICISER FROM PLASTICISED PVC FOILS... 

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