The degradation behaviors(mass loss,tensile strength,crystallinity index,and microstructure)of sisal fibers immersed in sodium hydroxide solution with pH of 13.6,12.9,and 11.9 were investigated via X-ray diffraction a...The degradation behaviors(mass loss,tensile strength,crystallinity index,and microstructure)of sisal fibers immersed in sodium hydroxide solution with pH of 13.6,12.9,and 11.9 were investigated via X-ray diffraction and scanning electron microscopy.A three-stage degradation process of natural fibers in an alkaline environment was proposed.The results showed that the sisal fibers exhibited a sharp mass loss over the first 7 d of degradation under all pH conditions,attributable to the rapid hydrolysis of lignin and hemicellulose at the fiber surface.The sisal fibers degraded at pH 12.9 and 13.6 over 1 month exhibited significantly lower tensile strengths(181 and 195 MPa,respectively)than the original fibers(234 MPa)because of the loosely bound structure of the component microfibrils caused by the hydrolysis of the linking lignin and hemicellulose.After 6-month degradation,stripped microfibrils occurred in the fibers,resulting in substantial degradation in tensile strength.The sisal fibers degraded at pH 11.9 largely maintained their integrity and tensile strength,even after 6 months,indicating that reducing the environment pH can effectively mitigate the degradation.展开更多
基金The Natural Science Foundation of China(No.52108191)the China Postdoctoral Science Foundation(No.2021M690622)+2 种基金the Changzhou Sci&Tech Program(No.CJ20210153,CE20205050)the Qing Lan Project of Jiangsuthe Young Sci-tech Talents Promoting Project of Changzhou。
文摘The degradation behaviors(mass loss,tensile strength,crystallinity index,and microstructure)of sisal fibers immersed in sodium hydroxide solution with pH of 13.6,12.9,and 11.9 were investigated via X-ray diffraction and scanning electron microscopy.A three-stage degradation process of natural fibers in an alkaline environment was proposed.The results showed that the sisal fibers exhibited a sharp mass loss over the first 7 d of degradation under all pH conditions,attributable to the rapid hydrolysis of lignin and hemicellulose at the fiber surface.The sisal fibers degraded at pH 12.9 and 13.6 over 1 month exhibited significantly lower tensile strengths(181 and 195 MPa,respectively)than the original fibers(234 MPa)because of the loosely bound structure of the component microfibrils caused by the hydrolysis of the linking lignin and hemicellulose.After 6-month degradation,stripped microfibrils occurred in the fibers,resulting in substantial degradation in tensile strength.The sisal fibers degraded at pH 11.9 largely maintained their integrity and tensile strength,even after 6 months,indicating that reducing the environment pH can effectively mitigate the degradation.
