This study investigates the morphological and physical/end-use properties of corn cob powder-filled recycled polypropylene composites. The composites were prepared by incorporating corn cob powder of particle sizes 150 µm, 300 µm and 425 µm respectively at filler loadings of 5 to 25 wt%. The properties were determined according to standard test procedures. Results showed that the incorporation of corn cob powder as filler resulted to enhancement of water absorption and solvent sorption, which were found to increase with both increase in filler loading and increase in filler particle size, probably due to the hydrophilic nature of corn cob powder. It was also discovered that solvent sorption was most pronounced with benzene, followed by toluene and lastly xylene, in accordance with the relative proximity of their solubility parameters to that of polypropylene. Flame propagation rate was also found to improve by the incorporation of corn cob powder due to its high content of cellulose, a combustible organic matter. However, specific gravities of the composites were found to be lower than for the unfilled polypropylene, an implication that the composites produced are lighter in weight than the unfilled. Specific gravity increased with increase in filler loading but decreased with increase in particle size. The Morphological studies showed increase in the number of spherulites with increase in filler loading and increase in the size of the spherulites with increase in particle size. Further observation showed that the particle sizes and pores sizes detected increased with increase in filler particle size probably due to poor interaction and distribution of coarse particles. It is hoped that this present study will to help place the usefulness of corn cob as filler in the development of thermoplastic composites in future and develop its niche in the scientific record.
Bauxite deposits for production of alumina are lacking in Nigeria and there is an aluminium smelter plant in the country which requires alumina for its operation. Development of alternative alumina resource using clays that are abundant in the country is the focus of this paper. The thermal activation of Ibere clay from southeastern Nigeria for optimal leaching of alumina was investigated. The clay assayed 28.52% Al 2 O 3 and 51.6% SiO 2 , comprising mainly kaolinite mineral and quartz or free silica. The alumina locked up in the clay structure was rendered acid-soluble by thermal activation which transformed the clay from its crystalline nature to an amorphous, anhydrous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500˚C, 600˚C, 700˚C, 800˚C, and 900˚C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000˚C (holding for 60 minutes) were used in the control experiments. The result of leaching the clay calcines in 1 M hydrochloric acid solution at room temperature, showed that the clay calcines produced at 600˚C (holding for 60 minutes) responded most to leaching. Samples calcined for 60 minutes also responded better than those held for 30 or 90 minutes. Based on activation energy studies, it was observed that calcines produced at 600˚C (for 60 minutes) had both the highest leaching response (50.27% after 1 hour at leaching temperature of 100˚C) and the lowest activation energy of 24.26 kJ/mol. It is concluded therefore that Ibere kaolinite clay should be best calcined for alumina dissolution by heating up to 600˚C and holding for 60 minutes at that temperature. The clay deposit has potential for use as alternative resource for alumina production in Nigeria where bauxite is scarce.
The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated), E 308-16(lime-titania coated) electrodes, and TIG welded joints fall within the range of 1.5 ≤ Cr eq. /Ni eq. ≤ 1.9 and solidified with a duplex mode and were found to be resistant to solidification cracking. The E 308-16 weld metal had the greatest resistance to solidification cracking. Joints produced from E 310-16 had Cr eq. /Ni eq. ratio < 1.5 and solidified with austenite mode. It was found to be susceptible to solidification cracking. E 312-16 produced joints having Cr eq. /Ni eq. ratio > 1.9 and solidified with ferrite mode. It had a low resistance to solidification cracking.
Abstract. This study investigates the morphological and physical/end-use properties of corn cob powder-filled recycled polypropylene composites. The composites were prepared by incorporating corn cob powder of particle sizes 150 µm, 300 µm and 425 µm respectively at filler loadings of 5 to 25 wt%. The properties were determined according to standard test procedures. Results showed that the incorporation of corn cob powder as filler resulted to enhancement of water absorption and solvent sorption, which were found to increase with both increase in filler loading and increase in filler particle size, probably due to the hydrophilic nature of corn cob powder. It was also discovered that solvent sorption was most pronounced with benzene, followed by toluene and lastly xylene, in accordance with the relative proximity of their solubility parameters to that of polypropylene. Flame propagation rate was also found to improve by the incorporation of corn cob powder due to its high content of cellulose, a combustible organic matter. However, specific gravities of the composites were found to be lower than for the unfilled polypropylene, an implication that the composites produced are lighter in weight than the unfilled. Specific gravity increased with increase in filler loading but decreased with increase in particle size. The Morphological studies showed increase in the number of spherulites with increase in filler loading and increase in the size of the spherulites with increase in particle size. Further observation showed that the particle sizes and pores sizes detected increased with increase in filler particle size probably due to poor interaction and distribution of coarse particles. It is hoped that this present study will to help place the usefulness of corn cob as filler in the development of thermoplastic composites in future and develop its niche in the scientific record.
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