Experimental study of molten bubble layer growth and bubble size distribution in post‐flame‐spread <scp>PMMA</scp> samples

Although thermoplastics possess many desirable traits as solidified materials, they are combustible and burn readily. Post burning samples of polymethylmethacrylate (PMMA) the focus this study. During flame spread, PMMA forms a bubble containing molten surface layer that influences spread rate mass efflux. This study examines formation distribution bubbles inside sample has previously been subjected to then re-hardened into its solid state. Experiments discussed herein were conducted in Narrow Channel Apparatus (NCA), which reduces gravitation (buoyancy) on spread. Bubble sizes counts determined using digital image analysis (DIA). The burnt analyzed by dividing images eight equal area sections. Frequency distributions size (area) compared. Distribution functions fitted against empirical probability density function (PDF) for distribution. log-normal predicts all segments. can be used describe physical processes polymeric material it undergoes thermal transformation spreading flame.