Microscopic studies on the polymers decomposition in a closed volume at elevated temperatures in the presence of bulk NiCr alloy

In the present work, self-disintegration of the bulk metallic Ni–Cr alloy in the presence of different polymer compounds under the conditions of closed volume and elevated temperatures is studied. It was found that in the cases of polymers containing in addition to carbon only hydrogen atoms (polyethylene) or only halogen atoms (polytetrafluoroethylene), self-disintegration does not proceed noticeably even at temperatures as high as 800 °C. The predominating form of the solid product is non-catalytic carbon shaped as microspheres or their sintered agglomerates. On the contrary, for decomposition of the polymer containing hydrogen and halogen atoms (polyvinylchloride), self-dispersion of the bulk alloy is significantly facilitated. This process is accompanied with formation of catalytically derived forms of structured carbon within all the studied temperature range (500–800 °C). The most common form of the carbon deposits is nanofibers. At the same time, some unusual carbon structures were observed, among which the solid-phase carbon–nickel microcrystals of a regular cubic shape with pyramidal cavities on each facet are of special interest. The studied process can be considered as an alternative approach for utilization and recycling of the plastic wastes.