Fine reclaim powder

Mixtures can be separated by physical means because each component retains its properties (Figures 1-6 and 1-7). For example, a mixture of salt and water can be separated by evaporating the water and leaving the solid salt behind. To separate a mixture of sand and salt, we could treat it with water to dissolve the salt, collect the sand by filtration, and then evaporate the water to reclaim the solid salt. Very fine iron powder can be mixed with powdered sulfur to give what appears to the naked eye to be a homogeneous mixture of the two. Separation of the components of this mixture is easy, however. The iron may be removed by a magnet, or the sulfur may be dissolved in carbon disulfide, which does not dissolve iron (Figure 1-6). 

Improvements have also been made in materials. Stricter control of particle size distribntion improves powder handling and transport characteristics, spray patterns, and transfer efficiency (105,106). Reduction of the snperfine fraction, ie, particles below abont 8-10 also results in less fines in the overspray powder and less load on the reclaim system (107). More spherical powders charge more efficiently and show improved spraying characteristics (108). 

Most polymers can be analysed as received, as pellets, powders, films, fibres, in solution, or even as whole articles such as mouldings. Fine fibres can present some difficulties if a Raman microscope is not available. Raman spectroscopy has found applications in the identification of polymers in which additives obscure the polymer peaks in the IR spectrum. Reclaimed polymer is more prone to fluorescence than virgin material, causing problems for Raman analysis [394], Laser-Raman spectroscopy often allows polymer identification (e.g. in recycled material) only in conjunction with IR spectroscopy. Raman spectroscopy has been used to examine weathered PVC plasticised with DOP, DOA and BBP for dehydrochlorination [395], Laser-Raman spectroscopy has also been proposed as a suitable method for precise detection of ageing deterioration of vinyl chloride resins containing plasticisers and fillers used as electrical wire and cable coatings [396]. 

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