Evaluating recyclability of fly ash reinforced polyvinyl chloride foams

Abstract

Using fly ash as a reinforcing filler can be very cost effective; however, the recycling of postconsumer products containing fly ash is of a considerable concern. In this study, the recycling of processed polyvinyl chloride (PVC) foam reinforced with fly ash was investigated by evaluating the effect of regrind content (up to 40 wt%) and fly ash content (up to 20 wt%) on the physical, mechanical, microstructural, and processing properties of the composites. Experimental results show an increase in the foam density with increasing regrind and fly ash contents. The melt viscosity increased with increasing the regrind concentration; however, it dropped with increasing the fly ash content. The tensile strength increased with increasing the regrind content, indicating a good degree of gelation in the composites. Meanwhile, the charpy impact strength of the composites decreased due to the high rigidity of fly ash particles. Dynamic mechanical analysis show that the storage modulus improved with both the addition and increasing the amount of regrind, which confirmed good stress transformation between the polymer foam matrix and the fly ash particles. The polymer matrix morphology, as was determined by scanning electron microscopy (SEM), confirmed uniform foam structure even with the addition of 40 wt% regrind in the virgin PVC. J. VINYL ADDIT. TECHNOL., 00:000-000, 2016. V C 2016 Society of Plastics Engineers INTRODUCTIONRigid polyvinyl chloride (PVC) foam is regarded second to polyurethane foam in its worldwide consumption. It is mainly produced using blowing agents which generate gas by thermal decomposition [1]. Over the past few decades, PVC foam has been established as the main wood replacement in window frames, window blinds, decorative trimming, furniture components, and other applications [1,2]. The higher production of PVC foam products generates substantial quantities of scrap material, which makes the recycling of PVC foam scrap to be one of the main challenges to be addressed.Many researchers have concentrated on studying the recyclability of rigid PVC products and their scrap materials. Sombatsompop and Thongsang [2] evaluated the effect of recycling PVC pipes (varying from 0 to 80 wt%) on the rheological, morphological, mechanical, and thermal properties of two commercial PVC virgin PVC blends. They reported an increase in the melt viscosity with increasing the recycled PVC content. However, the ratio of die swelling did not change significantly with varying the recycled concentration, while this ration increased at very high temperatures. They also reported that the maximum amount of recyclate that can be added to virgin PVC bottle and PVC pipe grades, to achieve the optimum ultimate tensile strength (UTS), is 40 and 80 wt%, respectively. Rabinovitch et al. [3] reported that, in order to achieve a smooth surface in a PVC regrindincorporated sample, the melt temperature of the secondary extrusion must be at least 8-108C higher than its previous heat history. Ditta et al. [4] investigated the recyclability o...

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