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The use of lignocellulosic materials from agricultural resides, such as cereal straws and sugarcane bagasse, as a source of chemicals has received considerable interest in recent years, since fossil fuels available on earth will be exhausted by around the year 2040, while agricultural residues are abundant and renewable.Ethylation is one of the most versatile functionalization procedures as it provides access to bio-based materials with valuable properties such as inspissation, filming, emulsification, suspension, water maintaining and binding, etc.Ethylated polymers have been used for many applications, such as printing and dyeing, medicine, food, textures, toilet, oil drilling, electrical elements, etc.The chemical modification of sugarcane bagasse with ethyl bromide using THF as solvent after alkaline activation was studied.The parameters optimizcd included alkaline activation time of 0-120min, ethyl bromide concentration by the ration of dried sugarcane bagasse to ethyl bromide from 1 ∶ 1 to 1∶5, reaction time of 1-5h and reaction temperature of 90-130℃ required in the process.The extent of the etherification was measured by yield percentage and ethoxyl content which increased with an increment of alkaline activation time from 0 to 60min and ethyl bromide concentration between 1∶3 and 1∶5.It should be noted that an increasing the temperature above 100℃ had a detrimental effect on the etherification.Evidenccs of etherification of the bagasse were provided by FT-IR and 13C-NMR and the results showed that the etherification of the sugarcane bagasse cellulose and hemicellulose mainly occurred at C-2 and C-3.Molecular weights, ethoxyl content and thermal stability were investigated in detail by GPC, GC and TGA, respectively.The molecular weight and thermal stability of the ethylated bagasse decreased upon chemical modification.