Polymer applications additive migration

Applications Applications of UV/VIS spectrophotometry can be found in the areas of extraction monitoring and control, migration and blooming, polymer impregnation, in-polymer analysis, polymer melts, polymer-bound additives, purity determinations, colour body analysis and microscopy. Most samples measured with UV/VIS spectroscopy are in solution. However, in comparison to IR spectroscopy additive analysis in the UV/VIS range plays only a minor role as only a limited class of compounds exhibits specific absorption bands in the UV range with an intensity proportional to the additive concentration. Characteristic UV absorption bands of various common polymer additives are given in Scheirs [24],... 

Penetrant Concentration-Plasticization Polymer Molecular Structure Relaxation-Controlled Transport Applications of Transport Concepts Barrier Materials Devolatilization Additive Migration Dyeing... 

Additives are incorporated by the resin manufacturer and/or by the packaging processor. The presence of additives in packaging applications raises the question of additive migration. Most additives diffuse within the polymer and often tend to migrate to the surface of the material. When a packaged product is in direct contact with a compounded polymer, there may be a transfer of the additive to the product. (Of course, it is also possible for components of the product to be transferred to the polymer.) The extent of transfer depends on a series of conditions, and is discussed in Chapter 13. We will briefly examine compounding, and then discuss some common additives used in packaging. 

Identification and eventual determination of polymer additives is an important issue in many fields, mainly in the area of packaging materials where additive migration from food contact materials may have potential toxic effects in humans.In biomedical applications, plasticizers present in the polymer [e.g., Di(2-ethylhexyl) phthalate (DEHP) in PVC] will readily leach into the liquids passing through it, particularly for lipid-containing fluids, e.g., blood. There is a great concern about the toxicity of DEHP, especially for risk groups such as... 

The main requirements for contact with food are that the article must not impart odour or taste to the food and should be suitable for the intended application. Additives, monomers, catalyst residues, polymer degradation products and so on can migrate into any food in contact if the concentration of these substances is lower in the food than in the plastic. The migration is dependent on temperature and time the rate of migration is inversely proportional to molecular weight. The migration of these species could produce toxicity or the formation of undesirable flavours or odours, known as organoleptic problems. 

Thus a suitable volume of the 2 ml extracts for application to the plate is 0.1 ml (which contains 500-1000 pg of each additive if complete additive migration from the polymer has occurred and 50-100 pg of each if only 10% additive migration has occurred). 

The ionic conductivity is generally seen with an amorphous polymer. The ion diffusion in a polymer electrolyte is assisted by the local motion of the polymer chain. Therefore, the polymer chain must be flexible at the application temperature. This is conventionally achieved by choosing a polymer with a glass transition temperature (Tg) below the temperature being used or by blending it with another polymer and/or additives. At the same time, it needs to have sufficient mechanical stability for such an application. However, there are some vitreous solid electrolytes which are used above Tg in which ion diffusion is decoupled from the motion of the matrix polymer. The cation migration with segmental mobility of the polymer chain is shown in Fig. 11.2. ... 

Carbon black may serve as a low-cost additive for controlling the gas migration in cement slurries [303]. It is intended as a suitable substitute for polymer latex and silica fume and has been tested in field applications [304,1256]. The concentration of carbon black varies from 2 to 20 parts, based on the weight of the dry cement [1220]. The particle size varies from 10 to 200 nm. A surfactant is necessary for dispersion, for example, formaldehyde-condensed naphthalene sulfonate or sulfonated cumarone or indene resins. 

Columns filled with polymer solutions are extremely simple to prepare, and the packing can easily be replaced as often as desired. These characteristics make the pseudostationary phases excellent candidates for use in routine CEC separations such as quality control applications where analysis and sample profiles do not change much. However, several limitations constrain their widespread use. For example, the sample capacity is typically very low, pushing typical detection methods close to their sensitivity limits. Additionally, the migration of the pseudostationary phase itself may represent a serious problem, e. g., for separations utilizing mass spectrometric detection. The resolution improves with the concentration of the pseudostationary phase. However, the relatively low solubility of current amphiphilic polymers does not enable finding the ultimate resolution limits of these separation media [88]. 

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