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The conversion of a solid copolymer (ViSiHNH),-(MeSiHNH), into a ceramic was studied in the 2&145O"C temperature range under different atmospheres (inert or oxidative). The ceramic yield, the ceramic composition, and the gaseous evolution directly depend on the heating rate, the pyrolysis atmosphere, and the duration of pyrolysis. The implications of these observations to the pyrolysis mechanism are discussed. The silicon carbonitride obtained after pyrolysis is amorphous up to 1400°C with high carbon content. It will be shown in Parts I1 and 111 that either SIC or Si3N4 could be selectively crystallized depending upon processing conditions.

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Highlights• Marine debris was studied on 15 islets of St. Brandon's Rock, Indian Ocean • Plastics made up 79% of 50 000 debris items at 0.74 items m -1 shore length Intact CFLs suggests product-facilitated long-range transport of mercury. We suspect that aggregated marine debris, scavenged by the islands from currents and gyres, could re-concentrate pollutants. SBR islets accumulated debris types in different proportions suggesting that many factors act variably on different debris types. Regular cleaning of selected islets will take care of most of the accumulated debris and may improve the ecology and tourism potential. However, arrangements and logistics require more study.