THERMAL CHARACTERISATION STUDY OF TWO DISPOSABLE DIAPER BRANDS

Abstract

Disposable diapers have become a prominent feature of solid waste dumped in landfills. It is estimated that disposable diapers take anywhere between 300 to 500 years to decompose. Despite the associated environmental challenges, a plethora of studies show that disposable diapers have become a popular choice for parents when compared with cloth diapers. Disposable diapers are argued to be more convenient for parents because of their once-off use and super-absorbent ability, of which they are able to absorb 200-300 times the weight as compared to the cloth diapers. This study investigates thermal devolatilisation profiles of disposable diapers as well as their iso-conventional kinetic parameters, elemental and fractional composition. In this study, the two most dominant disposable diaper brands were sampled and analysed qualitatively and quantitatively. It was observed that the exterior fraction of both diapers showed a single peak devolatilisation at a temperature of around 500°C, while the interior fraction showed two distinctive devolatilisation peaks observed below 400°C and above 500°C. However, the pyrolysis heating rate produced no effect on the pyro-char fraction. Furthermore, the devolatilisation pathways of different types of disposable diaper fractions showed that there is a potential for conducting stepwise pyrolysis to promote fractional recovery of valuable products. Disposable diapers waste conversion can be better handled by separating the outer fraction (mainly fossil-based plastics and rubbery materials) from the inner fraction (mainly bio-based fibers and absorbents). It is further illustrated that the kinetic parameters, Ea and k0 are different for each disposable diaper fraction.