Processing of primary sludge of pulp industry as microfillers for polystyrene-based composite foams

Abstract

Primary sludge as main byproduct wastes in a pulping industry still contain some biomass and potentially affects the environment when was not handled properly. The pulp industry primary sludge (PIPS) can be processed as microfiller for polystyrene-based foam composites for various engineering applications, such as sound and vibration damping materials. The PIPS has been dried, milled and shieved to 100-400 mesh particle sizes. Physical and chemical properties of the PIPS have been tested using: particle size analysis (PSA), FTIR spectroscopy, then its thermal properties using differential scanning calorymetry (DSC). Incorporation of the PIPS microfiller in maleic anhydride-modified polystyrene (MA-m-PS) matrices for composite foam was carried out in a reflux reactor in xylene solution using Tween 80 as surfactant under stirring. The composite foam was characterized, firstly based on their densities compared to that of fresh PS resin, then using electron microscopy (SEM) for morphology properties. It was found that mean particle size of the dried and milled PIPS powder was 14.84 μm and its biomass content was 10.5%. Result of FTIR spectroscopy showed that many of the selected characteristic bands of lignocelluloses overlap, specifically, the selected band 1366 cm-1 for cellulose is very close to the 1368 cm-1 selected for hemicellulose. Whereas result of and its decomposition temperature 549.86°C with heat of combustion 16.34 cal/g, which indicating suitability of the PIPS powder as filler for polymeric foam microcomposites. The result of morphology analysis of the PIPS-filled microcomposites foam based on MA-m-PS (optimum weight ratio of MA-m-PS/PIPS: 80/20, density 0.88 g/cm3), using SEM showed that PIPS microfillers were well distributed within the MA-m-PS matrices.