Dripping behavior of vertical burning thermally thin PMMA with different spacings to wall.

Experiments were carried out to study the dripping behavior of vertical burning thermally thin poly(methyl methacrylate) (PMMA) with different spacings between the wall and PMMA. The dripping behavior was studied by infrared video image analysis with spacings of 7, 10, 13, 16, 19, 22, and 25 mm. As the spacing increased, the dripping time and mass and burnout growth distance first increased and then decreased. The critical value was observed at the 13 mm case. The dripping behavior is assumed to correspond to the net heat flux to the surface, extensional viscosity, and gravitational force of melting PMMA. After the dripping, the pyrolysis and burnout spread rates become asymptotically equal.In this study, the effects of spacing between the wall and fuels on the dripping behavior were investigated for the first time using uniform PMMA samples with 200 mm height, 50 mm width, and 2 mm thickness. [ABSTRACT FROM AUTHOR]