Plastic solvation

Commercial Plastisols, Accdg to definition given in Ref 2, a plastisol is a liquid dispersion of finely divided resin in a plasticizer. It is usually 100% solid with no volatiles when volatile content exceeds 5% of the total wt it is called organosol. When the plastisol is heated, the plasticizer solvates the resin particles, and the mass gels. With continued application of heat the mass fuses to become a conventional thermoplastic material... 

Plasticizers perform this function if a single plasticizer solvates the dissimilar major components of a blend. Phthalate esters help to stabilize mixtures of poly(vinyl chloride) and poly(melhyl methacrylate) for example. These materials are also plasticizers for polystyrene, and stable blends of this polymer with poly(vinyl chloride) can be made by adding dioctyl phthalate to a blend of polystyrene and rigid PVC. 

Flexricln P-8 plasticizer, sheeting Di (C7-9 alkyl) adipate plasticizer, shellac Ethyl toluenesulfonamide, Uniplex 108 plasticizer, silicone elastomers DImethIconol Masil SFR 70 Masil SFR 100 Masil SFR 750 Masil SFR 2000 Masil SFR 3500 Masil SFR 50,000 plasticizer, solution coatings Piccovar L60 plasticizer, solvating PVC Acetylated mono- and diglycerldes of fatty adds] Benzoflex 284 Propylene glycol dIbenzoate... 

It can be said that the greater the plasticizer solvation power, the greater the fragility effect and the more extended is the effect to higher concentrations of plasticizer [66]. For this reason the improvement of rigid PVC formulations is not made by the addition of small quantities of plasticizer but by the addition of lubricants that, instead of increasing the fragility, reduce it. 

Solvation—Desolvation Equilibrium. From the observation of migration of plasticizer from plasticized polymers it is clear that plasticizer molecules, or at least some of them, are not bound permanently to the polymer as iu an internally plasticized resia, but rather an exchange—equiHbrium mechanism is present. This implies that there is no stoichiometric relationship between polymer and plasticizer levels, although some quasi-stoichiometric relationships appear to exist (3,4). This idea is extended later ia the discussion of specific iateractions. 

Interaction Parameters. Early attempts to describe PVC—plasticizer compatibiHty were based on the same principles as used to describe solvation, ie, like dissolves like (2). To obtain a quantitative measure of PVC—plasticizer compatibihty a number of different parameters have been used. More recently these methods have been assessed and extended by many workers (7—9). In all cases it is not possible to adequately predict the behavior of polymeric plasticizers. 

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. 

It has been shown that the effects found are caused by specific solvation of both the PhAA ionogenic and other polar groups by the plasticizers used, as well as by the influence of ion-exchangers nature on the PhAA cations-anionic sites complex formation constants. 

The mode of action of plasticizers can be explained using the Gel theory [35 ]. According to this theory, the deformation resistance of amorphous polymers can be ascribed to the cross-links between active centres which are continuously formed and destroyed. The cross-links are constituted by micro-aggregates or crystallites of small size. When a plasticizer is added, its molecules also participate in the breaking down and re-forming of these cross-links. As a consequence, a proportion of the active centres of the polymer are solvated and do not become available for polymer-to-polymer links, the polymer structure being correspondingly loosened. 

Polarity. The increase in the polarity of the plasticizer (e.g. existence of polar groups, substitution of aryl groups by alkyl ones) reduces softening efficiency, worsens low-temperature properties of the plasticized polymers, improves solvation, and reduces extractability by aliphatic solvents. 

Solvation Process of swelling of a resin or plastic. Can be caused by... 

Thus, it can be concluded that in the present iono-mer system, zinc stearate plays a dual role. First, below its melting point it reinforces the matrix and strengthens the ionic aggregates and, second, at a higher temperature it results in solvation of the ionic aggregates and plasticizes the system, thus, facilitating the transition from the rubbery state to the viscous flow state [23]. 

One other long-term condition that takes place with relatively low level DC fields in the presence of moisture is the migration of the metal of the conductor into the plastic. This was discovered to be a common thing in the past with silver conductors and phenolic insulators. The first instance of field failures were discovered in telephone equipment. The problem can occur with other metals with phenolic and also conceivably with other plastics that are moisture sensitive and can have a solvating action on the conductor metals that they contact. Most of these type plastics should be avoided inside hermetically sealed containers with movable contacts. Vapors released from the organic plastic deposit on the contacts to produce an insulation layer leading to contact failure. 

A common technique used for polyolefin samples is to dissolve the sample using solvents such as xylene, decalin, toluene and di- or trichlorobenzene heated to temperatures as high as 130-150°C. After the plastic sample has been solvated, the polymeric component is precipitated by cooling and/or by adding a cold nonsolvent such as acetone, methanol or isopropanol. Polypropylene does not completely dissolve in toluene under reflux for 0.5 to 1 h with magnetic stirring (typically, 2g of polymer in 40 mL of toluene), yet the additives may be extracted [603]. In addition to additives, most solvents also extract some low-MW polymer with subsequent contamination of the extract. To overcome this a procedure for obtaining polymer-free additive extracts from PE, PP and PS has been described based on low-temperature extraction with n-hexane at 0°C [100],... 

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