Plasticizer migration, poly vinyl

Plasticizers. Plasticizers are materials that soften and flexibilize inherently rigid, and even britde polymers. Organic esters are widely used as plasticizers in polymers (97,98). These esters include the benzoats, phthalates, terephthalates, and trimeUitates, and aUphatic dibasic acid esters. Eor example, triethylene glycol bis(2-ethylbutyrate) [95-08-9] is a plasticizer for poly(vinyl butyral) [63148-65-2] which is used in laminated safety glass (see Vinyl POLYMERS, poly(vinyl acetals)). Di(2-ethyUiexyl)phthalate [117-81-7] (DOP) is a preeminent plasticizer. Variation of acid and/or alcohol component(s) modifies the efficacy of the resultant ester as a plasticizer. In phthalate plasticizers, molecular sizes of the alcohol moiety can be varied from methyl to tridecyl to control permanence, compatibiUty, and efficiency branched (eg, 2-ethylhexyl, isodecyl) for rapid absorption and fusion linear (C6—Cll) for low temperature flexibiUty and low volatility and aromatic (benzyl) for solvating. Terephthalates are recognized for their migration resistance, and trimeUitates for their low volatility in plasticizer appHcations. 

Castle L, Gilbert J, Eklund T (1990) Migration of plasticizer from poly(vinyl chloride) milk tubing. Food Addit Contam 7 591-596... 

CPA. Copolymer alloy membranes (CPAs) are made by alloying high molecular weight polymeries, plasticizers, special stabilizers, biocides, and antioxidants with poly(vinyl chloride) (PVC). The membrane is typically reinforced with polyester and comes in finished thicknesses of 0.75—1.5 mm and widths of 1.5—1.8 m. The primary installation method is mechanically fastened, but some fully adhered systems are also possible. The CPA membranes can exhibit long-term flexibiHty by alleviating migration of the polymeric plasticizers, and are chemically resistant and compatible with many oils and greases, animal fats, asphalt, and coal-tar pitch. The physical characteristics of a CPA membrane have been described (15). 

ISO 105-X10 Textiles - Tests for colour fastness - Part XIO Assessment of migration of textile colours into polyvinyl chloride coatings ISO 264 1976 Unplasticized polyvinyl chloride (PVC) fittings with plain sockets for pipes under pressure - Laying lengths - Metric series ISO 265-1 1988 Pipes and fittings of plastics materials - Fittings for domestic and industrial waste pipes - Basic dimensions Metric series - Part 1 Unplasticized poly(vinyl chloride) (PVC-U)... 

Di(2-ethylhexyl) adipate is a liquid of low volatility, widely used as a plasticizer in flexible poly(vinyl chloride) products, notably food films, as well as in other plastics and in a number of other minor applications, such as lubricants and cosmetics. Occupational exposure may occur by inhalation of di(2-ethylhexyl) adipate as an aerosol during its manufacture and its use. Meat-wrapping workers may be exposed while cutting poly(vinyl chloride) film across a heated cutter. Food is the major source of exposure of the general population to di(2-ethylhexyl) adipate because of migration from poly(vinyl chloride) packaging, particularly into fatty foods such as cheese and meat. 

Polymer Science Series B 44, Nos. 1-2, Jan./Feb.2002, p.45-9 IR SPECTROSCOPY STUDY OF PLASTICIZER MIGRATION FROM POLY(VINYL CHLORIDE)-BASED COMPOSITIONS... 

THERMAL DEGRADATION OF POLY(VINYL CHLORIDE) PLASTISOLS BASED ON LOW-MIGRATION POLYMERIC PLASTICIZERS... 

Other Addition Polymers. There are few studies on other reported polymer and plastic components of landfills. Poly(vinyl chloride) seems to be inert in landfill showing no degradation in real-world tests (23,24) and laboratory simulations (25). In the latter study, plasticizer migration occinred with its subsequent biodegradation. 

An adhesive is a linear or branched amorphous polymer above its Tg. It must be able to flow on a molecular scale to grip surfaces. (This definition is not to be confused with polymerizable adhesive materials, present in monomeric form. These are tacky or sticky only in the partly polymerized state. Frequently they are cross-linked thermoset, finally. Contact with the surface to be adhered must be made before gelation, in order to work.) An example is the postage stamp adhesive, composed of linear poly(vinyl alcohol), which is plasticized by water (or saliva) from below its Tg to above its Tg. On migration of the water away from the adhesive surface, it sticks. ... 

As mentioned in the previous section, it is common practice to plasticize poly(vinyl acetate) intended for surface coatings by such materials as dibutyl phthalate, A limitation of external plasticizers of this kind is that they may eventually be lost by evaporation or by migration into the substrate, leaving an imperfect and brittle film. This limitation may be overcome by the use of copolymers and these are now widely used in surface coatings and other applications. Comonomers which may be employed for this purpose include alkyl (commonly 2-ethylhexyl) acrylates, fumarates and maleates. Typically, the copolymers contain 15—20% by weight of such comonomers. These... 

The photo-dechlorination of poly(vinyl chloride) in the presence of plasticizers is accompanied by chain scission and crosslinking. Photocrosslinking of poly(vinyl chloride) decreases plasticizers migration in flexible films, to only limited extent [606, 1693]. 

Common plasticizers, such as those based on phthalates or trimeUitates, have been used frequently, particularly with poly(vinyl chloride), allowing an otherwise hard material (e. g., drain pipes) to be used in flexible products (e.g., shower curtains or water hoses). Several recent studies showing migration of plasticizers out of materials during their lifetime has led to the development of more stable or less toxic plasticizers, such as citrates that are used in medical plastics (e.g., IV bags and tubing). A recent review paper covers the major uses of common plasticizers and discusses the numerous applications and research trends [10]. 

A wide variety of low molecular weight additives, such as plasticizers, antioxidants, UV stabilizers, pigments and antistatic agents are frequently incorporated into polymers to improve a property. Often these additives are simply dissolved in the polymer matrix and, consequently, they are liable to be extracted at a later time. This is especially the case if they are volatile or are soluble in a solvent which may later contact the polymer. One of the most common polymers in which additive migration is encountered is poly(vinyl chloride). 

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