The Effect of Nanoclay Particles on the Tensile Strength and Flame Retardancy of Polystyrene -Nanoclay Composite

ABSTRACT This study was conducted to evaluate the effect of nanoclay particles on the tensile strength and flame retardancy of polystyrene-nanoclay composite. To conduct the study, first using melt-intercalation method, and a twin-screw extruder was employed to prepare nanocomposite samples from polystyrene with 4, 5 and 6% nanoclay and then nanocomposite granules were injected into a mold using an injection machine. Of the parts thus prepared, tension samples were made and subjected to tensile tests. Further, to ensure proper morphology of nanocomposite, X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests were conducted. Results showed that by increasing nanoclay up to 5%, the tensile strength and modulus of elasticity were increased, while the strength were decreased when 6%, nanoclay was used. Furthermore, the findings of flame retardancy test indicated that there is a decrease in the heat released coupled with an increase in nanoclay proportion during ignition. This work is an applicable study that showed necessity and advantage of nanomaterials like nanoclay to elevate usability of plastics, a cheap and applicable product of industry and nature, via increasing tensile strength and flame retardancy. Furthermore, durability of plastics is one of the important factors to protect healthy nature. Hence, importance of such nanomaterials like nanoclay can be considered as substantial material, in this regard

Ethanol and Biomass Production from Spent Sulfite Liquor by Filamentous Fungi

Since filamentous fungi are capable of assimilating several types of sugars (hexoses and pentoses), they are potential candidates for bioconversion of spent sulfite liquor (SSL). Three filamentous fungi such as Aspergillus oryzae, Mucor indicus, and Rhizopus oryzae were investigated in this work. The SSL was diluted in order to obtain concentrations of 50, 60, 70, 80, and 90% and supplemented with two types of nutrients. The results from cultivations in shake flask showed that A. oryzae and M. indicus were not able to grow in pure SSL and SSL90% while R. oryzae could grow only in SSL50% and SSL60%. Cultivation with A. oryzae resulted in the highest yield of produced fungal biomass, while R. oryzae cultivation resulted in the lowest fungal biomass yield. Although, the mediums containing yeast extract, (NH4)2SO4, KH2PO4, CaCl2∙2H2O, and MgSO4∙7H2O as nutrients supplementations produced higher fungal biomass compared to the mediums containing NH4H2PO4 and ammonia, but there was no significant difference between two types of nutrients in terms of sugars and acetic acid consumption rate. The sugars consumption in M. indicus cultivation was faster than A. oryzae and R. oryzae cultivation. Acetic acid present in SSL was completely consumed during cultivation of all fungi. M. indicus was the best and fastest ethanol producer from SSL among the fungi examined, when yeast extract and salts were used as nutrients supplementations. Furthermore, no further improvement in ethanol concentration and rate of sugars consumption was obtained in medium supplemented with NH4H2PO4 and ammonia compared to medium containing yeast extract, (NH4)2SO4, KH2PO4, CaCl2∙2H2O, and MgSO4∙7H2O. On the other hand, the higher dilution of SSL resulted in a better fermentability, and better consumption of sugars and acetic acid