采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变...采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变化,研究了KH570-SiO_2及凝固浴温度对MF/PVA纤维结构与性能的影响。结果表明:KH570-SiO_2改性后MF/PVA浆液的稳定性有所提高,KH570-SiO_2改性后MF/PVA纤维的断裂强度有所下降,但纤维韧性有较大提高,纤维耐热性能和阻燃性能也有较大提高;随着凝固浴温度的升高,KH570-SiO_2改性MF/PVA纤维的特征热分解温度和极限氧指数(LOI)先增大后降低,纤维LOI均高于28%;纤维断裂强度随凝固浴温度的升高而增大,而纤维断裂韧性则呈现先降低后增大趋势;凝固浴温度为50℃时,制得的KH570-SiO_2改性MF/PVA纤维LOI为38.7%,纤维断裂强度和断裂伸长率分别为2.53 c N/dtex和5.17%。展开更多
In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total...In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total Al concentrations,by using column chromatography,ethanol-acetone resolving and SO_(4)^(2−)/Ba^(2+)displacement.The Al_(13) species yield was characterized by Al-ferron timed complexation spectropho-tometry and 27Al-NMR(nuclear magnetic resonance).The coagulation efficiency of Nano-Al_(13) ,PAC and AlCl_(3) in synthetic water was also investigated by Jar tests.The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al_(13) ,PAC and AlC_(13) were similarly investigated using a photometric dispersion analyzer 2000(PDA2000).The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations,while column chromatography could separate PAC solutions at low concentrations.The SO_(4)^(2−)/Ba^(2+)displacement method could separate PAC solutions at high concentrations.However,extra inorganic cation and anion could be added in the solution during separation.The coagulation efficiency and dynamic experimental results showed that Nano-Al_(13) with high positive-charged species was effective in removing turbidity and color.The dynamic process results showed that Nano-Al_(13) also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al_(13) conformation is more effective in charge neutralization.展开更多
文摘采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变化,研究了KH570-SiO_2及凝固浴温度对MF/PVA纤维结构与性能的影响。结果表明:KH570-SiO_2改性后MF/PVA浆液的稳定性有所提高,KH570-SiO_2改性后MF/PVA纤维的断裂强度有所下降,但纤维韧性有较大提高,纤维耐热性能和阻燃性能也有较大提高;随着凝固浴温度的升高,KH570-SiO_2改性MF/PVA纤维的特征热分解温度和极限氧指数(LOI)先增大后降低,纤维LOI均高于28%;纤维断裂强度随凝固浴温度的升高而增大,而纤维断裂韧性则呈现先降低后增大趋势;凝固浴温度为50℃时,制得的KH570-SiO_2改性MF/PVA纤维LOI为38.7%,纤维断裂强度和断裂伸长率分别为2.53 c N/dtex和5.17%。
基金This work was supported by the National Natural Science Foundation of China(Grant No.50678095).
文摘In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total Al concentrations,by using column chromatography,ethanol-acetone resolving and SO_(4)^(2−)/Ba^(2+)displacement.The Al_(13) species yield was characterized by Al-ferron timed complexation spectropho-tometry and 27Al-NMR(nuclear magnetic resonance).The coagulation efficiency of Nano-Al_(13) ,PAC and AlCl_(3) in synthetic water was also investigated by Jar tests.The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al_(13) ,PAC and AlC_(13) were similarly investigated using a photometric dispersion analyzer 2000(PDA2000).The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations,while column chromatography could separate PAC solutions at low concentrations.The SO_(4)^(2−)/Ba^(2+)displacement method could separate PAC solutions at high concentrations.However,extra inorganic cation and anion could be added in the solution during separation.The coagulation efficiency and dynamic experimental results showed that Nano-Al_(13) with high positive-charged species was effective in removing turbidity and color.The dynamic process results showed that Nano-Al_(13) also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al_(13) conformation is more effective in charge neutralization.