A Basic Study on Material Selection Process from Waste Polymers Utilizing Unsteady Heat Conduction

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In this research project, sticking phenomenon occurring between a polymer particle and a heated solid surface has been experimentally investigated, in order to obtain basic understandings about the material selection process from waste polymers, which are the mixture of various kinds of polymer materials, utilizing unsteady heat conduction and the sticking phenomenon occurring between the polymer and the heated surface. Obtained results are summarized as follows :(1) Sticking phenomenon of polymer particles occurring on a heated solid surface was investigated for various kinds of polymer materials. As the results, it was shown that the sticking between a polymer and a heated surface becomes evident when the initial temperature of heated surface exceeds a certain temperature (an onset temperature), and that the onset temperatures almost correspond to the glass-transition temperature or the melt temperature of polymeric materials and therefore differ for different kind of polymers. This … More means that the waste polymer of various kinds of materials may be separated in each material by utilizing the sticking phenomenon.(2) In general, waste polymer may have dirt or paint on its surface. Effects of the dirt or paint on the sticking phenomenon were experimentally examined. The results clearly showed that the dirt on the surface of polymer particles results in a slight rise of the sticking onset temperature, but that the sticking characteristics of polymer particles are hardly influenced by the dirt. To the contrary, paint on the polymer particles markedly affects the sticking characteristics. The sticking onset temperature becomes the middle of those for the base polymer and for the paint material.(3) The interface temperature at the contact point between a polymer particle and a heated surface was measured for various polymer materials and for various initial temperature of the heated surface. The results showed that, under the condition that the sticking between a polymer and a heated surface becomes evident, the interface temperature is a little bit higher than the glass-transition temperature/melt temperature of the polymer material. This results suggests that the sticking of polymeric materials is dominated not only by the "softening" of the polymer, but also by the enlargement of contact area due to deformation of polymer around the contact point.(4) Rheological properties of polymeric materials were measured around the sticking onset temperature in detail. It was shown that the sticking between a polymer and a heated surface becomes evident when the loss tangent of the polymer exceeds unity, and that under the condition the values of storage/loss moduli are about 10^6 Pa and are independent on the kind of polymer materials. Less