Abstract
Acrodur, aqueous polyacrylic acid solution and dispersion, has been developed as an alternative wood adhesive to phenolic and urea formaldehyde resins. It has many environmental benefits over the conventional thermoset resins that include its non-corrosive nature and non-emission of carcinogenic gases. It has superior tolerance to moisture during composite fabrication and thus drying of the preforms may be minimised or even eliminated contrary to most resins used in natural fibre biocomposites. The aim of this study was to produce optimised hemp fibre reinforced Acrodur resin biocomposites using nonwoven hemp fibre mats by varying Acrodur solution to dispersion ratio, relative humidity, curing time and temperature. The optimised biocomposites gave the best combination of 26.4MPa-cm3/g specific tensile strength and 4.4GPa-cm3/g specific Young’s modulus with 0.94g/cm3density. Thermogravimetric analysis (TGA) and contact angle measurement showed similar thermal stability and increased hydrophobicity of the biocomposites than those of the fibres. From the water immersion test, the path of wicking of water moleculesinto the biocomposites was believed to be rather straight than tortuous and about 43.5% loss of tensile strength and 57.1% loss of Young’s modulus were observed upon 4-week water immersion of the biocomposites.
Highlights
Zinc is primarily produced from sulphidic ores; some zinc is produced from oxide-carbonate ores and different secondary resources such as zinc ash, zinc dross, flue dusts of electric arc furnace, leach residues, etc
In the leaching process with sulfuric acid, it is observed that zinc is extracted with high efficiency, but the lead remains in the form of sulphate
Simitsonite ore was leached in presence of sulphuric acid solution for an economical research on zinc production
Summary
Zinc is primarily produced from sulphidic ores; some zinc is produced from oxide-carbonate ores and different secondary resources such as zinc ash, zinc dross, flue dusts of electric arc furnace, leach residues, etc. Pyrometallurgical and hydrometallurgical routes or their combination can be employed for treating secondary materials. The hydrometallurgical processes are regarded as more eco-friendly for treating such materials having a low zinc content [1,2]. In the most common hydrometallurgical zinc process, ZnO-rich calcine is first produced from sulphide or oxide-carbonate concentrates and leached with hot sulphuric acid solution. After liquid/solid separation, the pregnant solution is purified and electrowon for metallic zinc production. In some plants (e.g., Çinkur, Kayseri, Turkey), the zinc leach residue is stockpiled for future lead recovery [1,3]
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