Tensile and Hardness Property Evaluation of Kaolin- Sisal Fibre- Epoxy Composite

In this work, the tensile and hardness properties of Kaolin- sisal fibre- epoxy composite were evaluated using standard methods. Epoxy type 3354A with its hardener was mixed in the ratio 2:1. Calcined kaolin particle with average size of 35µm and 3-4mm sisal fibre were added to the epoxy matrix during the composite manufacture in a proportion of: 60/40 wt %, 60/30/10 wt %, 60/20/20 wt %, 60/10/30 wt % for matrix, fibre and Kaolin respectively. The green mixtures were poured into aluminum mould and left for 24 hrs to cure. The results showed that the addition of kaolin and sisal fibre affected mechanical properties of the epoxy resin. The maximum strain observed for each specimen after tensile tests were as follows: 12% for specimen A; 12% for specimen B; 3.9% for specimen C; 11.5% for specimen D and 6% for specimen E. The Shore D hardness values were as follows: 79.1 for specimen A (control); 55.68 for specimen B; 42.82 for specimen C; 78.7 for specimen D and 81.34 for specimen E. The hardness values was reduced from 55.68 to 42.83 and increased to 81.34. Specifically, the tensile and hardness properties increased proportionately with the fibre quantity and inversely proportional to the kaolin content. These are attributed to the level of bonding strengths between the fibre-matrix-particulate interfacial adhesions.http://dx.doi.org/10.4314/njt.v34i4.1

Extraction and characterization of chitin and chitosan from Nigerian shrimps

Chitin was synthesized from Nigerian brown shrimps by a chemical process involving demineralization and deproteinisation. Deacetylation of the chitin was conducted to obtain Chitosan. The chitin and chitosan were characterized using FTIR, XRD and SEM. Proximate and elemental analysis were also conducted. The percentage yield of chitin was 8.9%. The degree of deacetylation of chitin was found to be 50.64% which was a low value compared to previous works and can be attributed to the low alkali concentration and heating time. XRD patterns indicated that chitin was more crystalline than the corresponding chitosan. FTIR spectra indicated the presence of functional groups associated with different bands, the intensities and stretching established that the samples are chitin and chitosan. SEM analysis also indicated morphological differences between the chitin and chitosan.Keywords: Deacetylation, biodegradable, characterization, deproteinisation, demineralizatio

Surface texture and optical properties of crystalline silicon substrates

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Fashina, A. A., K. K. Adama, O. K. Oyewole, V. C. Anye, J. Asare, M. G. Zebaze Kana, and W. O. Soboyejo. "Surface texture and optical properties of crystalline silicon substrates." Journal of Renewable and Sustainable Energy 7, no. 6 (2015): 063119. and may be found at http://dx.doi.org/10.1063/1.4937117This paper presents the results of an experimental study of the effects of surface texture on the optical and light trapping properties of silicon wafers. Surface texture is controlled by anisotropic etching with potassium hydroxide (KOH) and isopropyl alcohol (IPA) solutions. The anisotropic etching of (001) crystalline silicon wafers is shown to result in the formation of {111} pyramidal facets on the surfaces of the wafers. A combination of profilometry, optical microscopy, scanning electron microscopy, and atomic force microscopy is used to study the effects of KOH/IPA etching on the morphology and roughness of the textured surfaces. The results show that IPA concentration has the strongest effect on the surface roughness of (001)-single crystal crystals at temperatures up to 80 °C. Above this value, evidence of temperature-induced cracking was revealed on the silicon substrate. The best volume concentration ratio of KOH:IPA is also found to be 2:4. The implications of the study are discussed for the design of light trapping in silicon solar cells