A unique strategy to obtain the “standard” burning character of thermoplastics using immediate ignition technique

This study proposes a unique strategy to provide the “standard” burning characteristic values of thermoplastics with the least effect of various dynamic and chemical factors, such as dripping by melting, bursting of the bubble formed inside the molten matter. Despite the recognized significant influence of these factors during the burning event, no systematic study has successfully addressed them, as previous attempts have not endeavored to eliminate these effects. In this study, a small ceramic sphere coated with a thin-layer Polymethylmethacrylate (PMMA), a representative thermoplastic material, served as the specimen. A tiny amount of ignition gel was incorporated into the specimen surface to facilitate immediate ignition and prevent polymer overheating and bubble formation during heating, thereby eliminating non-linear dynamic transport effects and achieving a quasi-steady state burning condition. Following examination of ignition delay time, burning process, burning rate constant, and B-number, the immediate ignition technology proposed in this paper was recommended as a satisfactory methodology for establishing a quasi-steady burning system. The burning rate constant without dripping and bubble bursting effects was then determined to be 1.04 mm 2 /s, and the corresponding “standard” B-number for PMMA was ultimately determined as 1.60. This outcome opens new avenues to examine the contribution of each factor (e.g. dripping, bubble bursting) on the burning characters, which is a prominent feature in fundamental combustion research of thermoplastic materials.