Effect of fly ash washing conditions on the properties of coupling agent modified polypropylene/fly ash composites

Abstract

Two fly ash samples (one from UK, UKFA, and another from South Africa, SAFA) were washed with water and 1 M hydrochloric acid (followed by water) prior to incorporation (at 65% wt) into polypropylene homopolymer, containing an unsaturated carboxylic acid coupling agent (Lubrizol Solplus® C800) with dicumyl peroxide free radical initiator. Melt blending was achieved using a Haake Rheomix 600 mixing chamber, and composite test plaques were compression moulded. Flexural and impact testing was then carried out. Unwashed and water washed fly ash–based composites responded well to C800 modification, and flow microcalorimetry (FMC) and diffuse reflectance Fourier transform infrared spectroscopy studies confirmed strong interaction between C800 and fly ash. However, washing the fly ash with HCl led to a reduction in composite flexural and impact properties. Scanning electron microscopy imaging of the latter composite fracture surfaces revealed poor filler‐matrix adhesion, which was thought to be due to reduced interaction between C800 and HCl washed fly ash. The latter was confirmed using FMC. Reduction of C800/fly ash interaction led to a reduction in the nucleation of polypropylene (PP) crystallization and a decrease in melt flow rate. The latter may be due to a shift in locus of PP–C800 addition reactions from the interfacial region to the bulk matrix. POLYM. COMPOS., 35:698–707, 2014. © 2013 Society of Plastics Engineers

Waste material fly ash as an alternative filler for elastomers

“…These alternative fillers include oil palm ash, 13,14 rice husk ash, 15,16 waste Aquilaria crassna wood, 17 coconut shells, 18,19 macadamia shells, 20 and fly ash (FA). [21][22][23][24] By-products are produced as waste in commercial industries or biological manufacturing, where waste is defined as inefficient materials and activities that do not add value to the product.…”

“…Hence, developing alternative fillers generated from by‐products or waste material is necessary to reduce the environmental pollution and replacing the current commercial fillers. These alternative fillers include oil palm ash, 13,14 rice husk ash, 15,16 waste Aquilaria crassna wood, 17 coconut shells, 18,19 macadamia shells, 20 and fly ash (FA) 21–24 …”