Anti-plasticisation

However, the diffusivity is influenced to a much greater extent by the factor y and the volume fraction of penetrant within the membrane, because both these terms appear in the exponent. The quantity y can be considered as a plasticising constant indicating the plasticising action of the penetrant on segmental motion (It may even occur that the penetrant acts as an anti-plasticiser that decreases rhe permeability but this is very exceptional and will not be considered further). For simple gases which hardly show any interaction with the polymer y => 0, and eq. V-119 reduces to a constant diffusion coefficient. 

The dependence E c p) adduced in Figure 8.6 compared with the plot of Figure 8.5 demonstrates that the maximum value of the elasticity modulus corresponds to the minimum melt viscosity. Therefore, the epoxy polymer is a plasticiser in melt and an anti-plasticiser in the solid-phase state for HDPE/EP nanocomposites [16]. 

Carter, E.V. (1988) A new synthesis process for the manufacture of lamellar iron oxides for pigment use in anti corrosive coatings. J. Oil and Colour Chem. Assoc. 5 132-133 Carty, P. White, S. (1999) Flammability studies on plasticised chlorinated poly(vinyl) chloride. Polymer Degradation Stability 63 455-463... 

The European Union is poised to announce that phthalate plasticisers pose no risk to either human health or to the environment. A five-year risk assessment into six phthalates, which are used extensively in PVC products, is nearing an end. In September, an EU Technical Meeting completed its assessments of DINP and DIDP and decided that the two needed no classification or labelling for environmental or health effects. DINP is the phthalate most often used in soft PVC toys and items intended to be put into childrens mouths, on which most of the recent anti-PVC furore has been focused. 

These have a pool of anti-viral agents acting in cooperation with certain plasticisers to maintain and increase the antiviral agent s efficacy. They may be used to make surgical gloves, condoms, surgical clothes, surgical operative fields,... 

Phosphate esters have been produced commercially since the 1920s and now have important applications as plasticisers, lubricant additives and synthetic-based fluids for hydraulic and compressor oils. Their first use in lubrication was as anti-wear additives. Later developments in aircraft hydraulic control systems, particularly during the Second World War, introduced phosphate esters as less flammable hydraulic fluids. As esters of orthophosphoric acid they have the general formula OP(OR)3, where R represents an aryl or an alkyl group or, very often, a mixture of alkyl and/or aryl components. The physical and chemical properties of phosphate esters can be varied considerably depending on the choice of substituents [59, 60], selected to give optimum performance for a given application. Phosphate esters are particularly used in applications that benefit from their excellent fire-resistant properties, but compared to other base fluids they are fairly expensive. 

Performance Films solar and safety films for glass, anti-glare films for electronic displays, polymer modifiers and plasticisers ... 

Artefacts may arise from sample and blank contamination, reactions and breakdown products within the chromatographic system. Examples of typical artefacts include acetal, silicone compounds, squalene, phthalate esters and other plasticisers and anti-oxidants. 

The monograph states that the nature and amount of additive used will depend on the type of polymer, the process used to convert it into a container and the intended purpose of the container. Approved additives include antioxidants, stabilisers, plasticisers, lubricants, colour and impact modifiers. Anti-static and mould release agents can be used only for containers for oral and external preparations. Specific permitted additives are given in the specification for the material within the pharmacopoeial monograph. 

Additives are used for a wide variety of purposes, and may be classified as fillers, anti-oxidants, stabilisers, plasticisers, fire retardants, pigments and lubricants. Anti-oxidants and stabilisers are usually used in rather small quantities in order to prevent degradation of the polymer when it is exposed to air, light and heat the intention here is to maintain the properties of the polymer rather than to modify them. Fillers may be used either simply to produce a cheaper product or to improve the properties, in particular the mechanical properties. Lubricants may be used externally, to prevent adhesion of the polymer to the processing equipment, or internally, either to aid flow during processing or to reduce friction between the product and other materials. 

Compounds containing both silicon and phosphorus are cited in the patent literature as useful anti-foaming agents, polymeric materials, plasticisers, oil additives and flameproofing agents. 

Tri-n-butyl phosphate is an effective anti-foaming agent which is used in paper making, printing ink manufacture, emulsion paints, and vat dyeing processes. It may be added to these systems as a 1-5 % solution in alcohol or acetone. Tri- -butyl phosphate can be used as a plasticiser or in low-temperature hydraulic fluids, but alternative tri-aryl derivatives are generally preferred (see above). The more important applications of orthophosphate esters are summarised in Figure 12.20. 

An examination is made of additives used in the formulation of water-based anti-corrosive coatings for metals based on carboxylated styrene-acrylate copolymer latices produced without surfactants. Pigments, fdlers, plasticisers, coalescing aids and corrosion inhibitors and their effects on the properties of coatings are discussed. (Part I Ibid., 72, No.4, April 1996, p.39-43). 

Many commercial polymers contain not only the base material, but also a plethora of performance-enhancing additives such as anti-oxidants, stabilisers, plasticisers, fillers and pigments. Consequently, characterisation of such commercial materials can become extremely complex, requiring skills not only in analysis of the components, but also in their deformulation . In chapter 2, several examples are given of systematic approaches to this type of problem in different systems. It is fascinating to observe the combination of traditional separation techniques, such as solvent extraction, with modem chromatographic and spectroscopic methods. 

As well as the direct production of polymers, vegetable oil derivatives have other uses in the polymer industry, for example as additives. Materials made from vegetable oil have many uses and are used to produce anti-static, slip, and plasticising agents, stabilisers, processing aids and as flame retardants (see Section 2.4.). They can also be incorporated into the manufacture of polyamides, polyesters and polyurethanes. 

Polyester plasticisers or polymeries are used in PVC compositions to confer the property of permanence, ie resistance to extraction by petrol or oil (important in tubing, oil seals, oil resistant industrial footwear, etc), low migration into other materials in intimate contact with the PVC (eg polystyrene in the case of refrigerator gaskets or the adhesives used in PVC insulation tape or decorative sheeting), and low volatility (important in high temperature electric cables and anti-fogging automobile upholstery and trim). 

Trimellitate plasticisers are very low volatility plasticisers with reasonable low temperature properties and efficiency. As esters of C7 to C q alcohols and trimellitic anhydride, they find their main application in high temperature electrical cables, although their exceptionally low volatility also makes them useful for anti-fogging automobile leathercloth. They have largely taken over from di-pen-taerythritol esters due to their better processing characteristics and better hydrolytic stability. 

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