From a fundamental and microscopic viewpoint to elucidate the possibility and availability of thermal recycling of wasted plastic resin, a series of heating processes of melting, thermal decomposition and burning of a spherical micro plastic resin particle having a diameter of about 200 μm are observed, when it is suddenly exposed to hot oxidizing combustion gas. Three ingenious devices are introduced; the first is a high-speed microscopic direct and schlieren system, the second is a pre-mixed mini-burner for abrupt heating, which is equipped with a pair of spark gaps at its exit and is discharged synchronously with the starting signal of high-speed camera, and the third is a single mini-puff generator, which enables to extinguish instantly all flames around the micro particle at an arbitrary assigned time after the spark ignition. Polyethylene terephthalate and polyethylene are used as two typical plastic resins. In this paper the dependency of internal and external appearances of residual plastic embers on the heating time and the initial plastic composition is optically analyzed, along with appearances of internal micro bubbling, micro jets and micro diffusion flames during abrupt heating. Based on temporal variations of the surface area of a micro plastic particle, the burning rate constant is also evaluated and compared with well-known volatile liquid fuels.

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