Development of a novel experimental technique for quantitative study of melt dripping of themoplastic polymers

This paper presents a methodology developed to quantitatively record the real-time melt and burn dripping behaviour of thermoplastic polymers. Six different commodity polymers were tested for their melt dripping behaviour exposed to convective heat in a purpose built electric furnace. The number, diameters and shapes of individual drops were measured and found to be influenced by the mechanism of decomposition of each polymer type. By conducting thermogravimetric analysis and measuring the viscosity of both the polymers and their molten drops, it could be established that the melt dripping is a combined effect of physical melting and polymer decomposition, which results in decrease in the viscosity of the molten drops. The effect of fire and heat on melt dripping was also observed in a UL-94 equivalent test where it was observed that the behaviour is quite different from pure melt dripping. Relationships between the glass transition temperature and melt viscosity with melt/flame dripping and burning intensity of these polymers have been observed. These will be studied in detail in a subsequent publication.