Plasticisers/plasticised polymers

This is an analytical technique used to obtain accurate quantification of the principal compound constituents such as plasticiser, polymer, carbon black and inorganic species, by monitoring weight loss across a temperature range. 

A kinetic model of the physical process of loss of plasticiser di-(2-ethylhexyl)-phthalate from plasticised PVC foil is developed. Experimental investigations are carried out using isothermal thermogravimetry in the temperature range of 120-150 deg.C. The thickness of the foil is 0.1 mm and the amount of the plasticiser in the plasticised polymer is 10-40%. The kinetic parameters... 

Demertzis, P.G., Riganakos, K.A., and Akrida-Demertzi, K., Study of compatibility of PVC and polyester-type plasticizer blends by inverse gas chromatography, Eur. Polym. J., 26(2), 137-140, 1990. Demertzis, P.G., Riganakos, K.A., and Akrida-Demertzi, K., An inverse gas chromatographic study of the compatibility of food grade PVdC copolymer and low volatility plasticisers, Polym. Int, 25, 229-236, 1991. 

Kumar, R., Pandey, A. K., Goswami, A., Shukla, R., Ramagiri, S. V., and Bellare, J. R. 2010. Plasticised polymer inclusion membrane as tunable host for stable gold nanoparticles. International Journal of Nanotechnology 7 953-966. 

Because of the extremely abrasive nature of reinforcing materials, they should be added downstream into already melted (plasticised) polymer. The melt can then act as a lubricant and reduce the rate of wear on screws and barrel. In addition, the fibres will be broken down to a lesser extent if they are fed downstream and this improves the product properties. 

There is a point when the NMR characteristics of a bulk polymer have to be treated as non-liquid-like, that is below the glass transition temperature. The NMR spectrum will then be dominated by static effects, such as the orientation dependence of chemical shift and the dipolar interaction. The earliest forms of solid-state polymer NMR were developed in the knowledge that these solid-state effects would be present, and would complicate the resulting data interpretations. Proton NMR studies of polymers have an impressive pedigree, and have relied on applications of a distinct solid-state theory. But it is only relatively recently that aspects of this theory have been refined to the point where experimental observations can be understood more fully. In particular, the process of spin diffusion is much better appreciated. Proton broad-line NMR does not necessarily require the use of large magnets and despite the theoretical uncertainties it has been widely accepted within the realms of rapid analysis. In its simplest form it has been used to quantify liquid and solid ingredients, for example, in plasticised polymers. 

Demertzis, P.G., Riganakos, K.A., and Akrida-Demertzi, K., 1991. An inverse gas chromatographic study of the compatibility of food grade PVdC copolymer and low volatility plasticisers. Polym. Int., 25 229-236. 

If we work back from solid polymer by adding progressively more amounts of liquid monomer, we see that the glass transition temperature of the now plasticised polymer decreases with the amount of monomer added. Monomer cannot diffuse through polymer below the glass transition temperature, so the reaction stops when the amount of monomer decreases by the amount necessary to raise the transition temperature of the mixture above the reaction temperature. However, the reaction will continue to proceed if the temperature of the reaction is raised, and will go to 100% conversion if the final temperature is above the transition temperature of the soHd polymer. For this reason, many industrial processes carry out the polymerisation using a temperature profile that finishes with a high temperature to ensure that there is no unreacted monomer left in the final product. 

The MFFT of the emulsion as formulated must be lower than any tempoature at which the paint is likely to be applied. For an indoor paint in the UK it is unlikely that temperatures below 10°C will be encountered, whilst the outdoor limit might be 5°C. Damage to paint films can occur should the ambient temperature fall below the Tg of the film. The Tg of a hard polymer, such as vinyl acetate, styrene or methyl methacrylate, can be reduced either by copolymerisation with a soft monomer or by adding an external plasticiser, such as butyl phthalate. On a cost effective basis external plasticisation is better for reducing the Tg. The snags are, firstly, that plasticisers are slowly lost through evaporation and, secondly, they can also diffuse into the substrate. The use of an internally plasticised polymer overcomes both problems and also saves the processing time necessary to incorporate an external plasticiser. 

If the stress-strain curve extends considerably beyond the yield point one speaks of a tough polymer the shape of the curve depends on the strain hardening behavior of the polymer and on the tendency to neck formation. Curve d) is characteristic for soft polymers, e.g. for thermoplastics at a temperature close to their glass transition temperature or plasticised polymers, which do not yet show rubber elastic behavior. 

This technique is useful in the analysis of compounded plastic samples. It is possible to obtain accurate quantifications of the principal compound constituents such as plasticiser, polymer and inorganic species. This data can be obtained on small (e.g., 10 mg) samples in a relatively short time (around 45 minutes). By the use of the temperature maxima at which weight events occur it is also possible to use the technique to obtain some qualitative assignments for the plasticiser and polymer. 

It is found that simple salts, such as LiCl, do not provide high conductivity. In general, the bulkier the anion, the higher is the conductivity. For example, Armand (1994) synthesised lithium bis(trifluoromethylsulphonyl)imide, LiN(CF3S02)2, and observed high conductivity when dissolved in PEO-type polymer electrolytes. The high conductivity is the result of a more plasticised polymer. 

Table 7.7 The composition and room temperature conductivity of some solid poiymer eiectroiytes (SPEs) and plasticised polymer films...

Whether the surface zone is a plasticised polymer layer overlaid with more additives or a more abrupt concentration gradient is unknown. The former model is, of course, close to a plasticised externally lubricated surface. Apart from the deliberate inclusion of external lubricants for service use there are undoubtedly cases where contaminants or additives included for other purposes fulfil this role. The waxy bloom on rubbers and free plasticisers on PVC are examples. There are also a group of additives which act as... 

In the case of poly(vinyl chloride) plastics, the FWA is mixed dry with the PVC powder before processing or dissolved in the plasticising agent (see Vinyl polymers). Polystyrene, acrylonitrile—butadiene—styrene (ABS), and polyolefin granulates are powdered with FWA prior to extmsion (2,78) (see... 

PVC. Poly(vinyl chloride) (PVC), a very versatile polymer, is manufactured by the polymerisation of vinyl chloride monomer, a gaseous substance obtained from the reaction of ethylene with oxygen and hydrochloric acid. In its most basic form, the resin is a relatively hard material that requites the addition of other compounds, commonly plasticisers and stabilisers as well as certain other ingredients, to produce the desired physical properties for roofing use. The membranes come in both reinforced and nonreinforced constmctions, but since the 1980s the direction has been toward offering only reinforced membranes. The membrane thickness typically mns from 0.8—1.5 mm and widths typically in the range of 1.5—4.6 m. 

Type AD-G is used in an entirely different sort of formulation. The polymer is designed for graft polymerisation with methyl methacrylate. Typically, equal amounts of AD-G and methyl methacrylate are dissolved together in toluene, and the reaction driven to completion with a free-radical catalyst, such as bensoyl peroxide. The graft polymer is usually mixed with an isocyanate just prior to use. It is not normally compounded with resin. The resulting adhesive has very good adhesion to plasticised vinyl, EVA sponge, thermoplastic mbber, and other difficult to bond substrates, and is of particular importance to the shoe industry (42,43). 

In summary, then, design with polymers requires special attention to time-dependent effects, large elastic deformation and the effects of temperature, even close to room temperature. Room temperature data for the generic polymers are presented in Table 21.5. As emphasised already, they are approximate, suitable only for the first step of the design project. For the next step you should consult books (see Further reading), and when the choice has narrowed to one or a few candidates, data for them should be sought from manufacturers data sheets, or from your own tests. Many polymers contain additives - plasticisers, fillers, colourants - which change the mechanical properties. Manufacturers will identify the polymers they sell, but will rarely disclose their... 

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