【作者】 刘国亮；

【导师】 郁崇文；

【作者基本信息】 东华大学 ， 纺织工程， 2012， 博士

【摘要】 苎麻原产于中国,主要分布在长江流域,我国年产量约占世界年总产量的90%,故有“中国草”之称。苎麻纤维具有良好的穿着服用性能,是一种优良的纺织原料。苎麻原料主要成分是纤维素。除此之外,还含有半纤维素、果胶、水溶物和木质素等胶质。在纺纱之前需将苎麻原麻中的胶质去除以满足纺纱要求,即“脱胶”。目前,苎麻脱胶方法主要有微生物脱胶和化学脱胶。微生物脱胶按其脱胶形式可分为传统微生物脱胶、细菌脱胶和生物酶脱胶三种。细菌脱胶、生物酶脱胶和化学脱胶均在一定程度上改善了传统微生物脱胶的精干麻品质。化学脱胶速度快、时间短、脱胶彻底、精干麻质量稳定。但是,化学脱胶工艺流程长、能耗大、污染大。细菌脱胶和生物酶脱胶时间长,脱胶不彻底,精干麻质量不稳定。但是,细菌脱胶和生物酶脱胶作用条件温和、环境污染小。本课题根据微生物脱胶和化学脱胶的特点,对当前苎麻传统化学脱胶工艺进行研究分析,针对化学脱胶工艺存在的流程长、能耗大和污染大等问题,使用新型的环境友好型过氧化物——过碳酸钠对苎麻进行脱胶处理,研究温度、时间、过碳酸钠浓度等因素对苎麻脱胶效果的影响。实验结果表明,过碳酸钠脱胶的最优工艺为：煮练温度95℃,煮练时间150min,过碳酸钠浓度18%,螯合剂(EDTA)2%,三聚磷酸钠2%,耐碱渗透剂2%,浴比1：12。本课题分别在安徽省华龙麻业有限公司和湖南省沅江明星麻业有限公司对过碳酸钠脱胶的最优工艺进行了实验验证,结果表明,精干麻纤维的断裂强度能够达到传统化学脱胶(“二煮一漂”)工艺92%左右的水平。而且,过碳酸钠脱胶的精干麻并丝情况也优于传统化学脱胶。XRD分析表明,过碳酸钠脱胶的精干麻纤维的结晶度小于传统化学脱胶的精干麻纤维的结晶度,由此也可以对过碳酸钠脱胶的精干麻断裂强度低于传统化学脱胶作出解释。从SEM图片可以看出,过碳酸钠脱胶后包覆在苎麻纤维周围的胶质基本去除,苎麻纤维的横节和竖纹都能够清晰的看到,但纤维素表面有裂缝,纤维受到了损伤。过碳酸钠脱胶的精干麻Na元素测试结果也证明,过碳酸钠脱胶的精干麻中纤维素受到了损伤,产生了氧化纤维素和碱纤维素。ATR图谱分析表明,过碳酸钠脱胶后精干麻中的胶质基本去除,但精干麻中还含有半纤维素和木质素。过碳酸钠脱胶的精干麻化学组成测试结果也证明精干麻中含有较多的半纤维素。煮练废液的COD、pH和色度测试结果表明,过碳酸钠脱胶对环境的污染程度远低于传统化学脱胶工艺。过碳酸钠在水溶液会产生碳酸钠和过氧化氢,因此,过碳酸钠的分解速度,以及过氧化氢分解速度的研究对于提高过碳酸钠的脱胶效果具有十分重要的意义。实验发现,中性条件下,过氧化氢在温度低于70°C时能够保持较为稳定的状态。同时,过氧化氢的分解速度随着过氧化氢浓度的增加而增加。碱性条件下,过氧化氢的分解速度大于中性条件下的分解速度。当氢氧化钠浓度一定时,过氧化氢的分解速度随浓度的增加而增加。当过氧化氢浓度一定时,随着氢氧化钠浓度的增加,过氧化氢分解速度增加。因此,在中性条件下,使用过氧化氢对实验原料进行脱胶或漂白处理时,温度以不低于70°C为宜。在碱性条件下,使用过氧化氢对苎麻进行脱胶处理时,过氧化氢的浓度以不低于6g/L为佳,氢氧化钠浓度为2-4%时为佳。升温过程中,当过碳酸钠脱胶原液中放入苎麻原麻后,过碳酸钠的分解速度大于不放入苎麻原麻时的分解速度。这是由于苎麻原麻中含有较多的灰尘、金属等杂质,这些杂质会促进过氧化氢的无效分解；同时,过碳酸钠同原麻中的胶质也发生了作用,导致放入苎麻原麻后过碳酸钠的分解速度大于不放入苎麻原麻时的分解速度。此外,在升温过程中,当过碳酸钠脱胶原液中不放入苎麻原麻时,过碳酸钠在温度低于80°C的条件下能够保持较为稳定的状态。当温度从80°C升温至90°C的过程中,过碳酸钠能够发生明显的分解现象。但是,过碳酸钠脱胶原液中放入苎麻原麻后,不管温度如何变化,过碳酸钠都会发生较为明显的分解现象。而且,当温度为90°C时,保持温度不变,90min后过碳酸钠脱胶原液中过碳酸钠的浓度接近于0。因此,使用过碳酸钠对苎麻原麻进行脱胶处理时,其煮练时间以90min左右为宜。为了稳定过氧化氢的分解速度,避免或减小过碳酸钠脱胶过程中过氧化氢的无效分解,降低过氧化氢对纤维素的氧化程度,本课题分析了稳定剂在过碳酸钠脱胶工艺中的应用。结果表明,同不添加稳定剂的过碳酸钠脱胶工艺相比,添加稳定剂P5之后,精干麻的断裂强度和断裂伸长率都得到了改善。江西省恩达家纺的实验验证结果也表明,添加稳定剂P5之后,精干麻的性能指标都有一定的提高。为了降低过碳酸钠脱胶工艺中过碳酸钠的用量,减少纤维素的损伤。本课题使用碱性果胶酶对苎麻原麻进行脱胶前处理。同时,利用过碳酸钠的氧化性和漂白性对碱性果胶酶脱胶前处理后的苎麻进行煮练,并将生物酶法脱胶工艺中的“失活”、“精练”和“漂白”三道工序合并为“过碳酸钠脱胶”一道工序,缩短工艺流程、提高生产效率。实验发现,碱性果胶酶-过碳酸钠脱胶的前处理最优工艺为：温度60℃,时间3h,碱性果胶酶浓度1.0g/L,pH值8.5。根据过碳酸钠分解情况的实验结果,在过碳酸钠煮练工艺中,煮练时间减少30min,确定为120min,过碳酸钠的用量由18%降低至12%,温度由95℃降低至90℃。SEM图片表明,碱性果胶酶-过碳酸钠脱胶的精干麻中包覆在纤维周围的胶质基本被去除,纤维表面光洁。ATR图谱分析表明,碱性果胶酶-过碳酸钠脱胶的精干麻中果胶得到了有效的去除,但是精干麻中还存在有半纤维素物质。精干麻的化学组成测试结果也对该实验结果作出了证明。XRD分析结果表明,碱性果胶酶-过碳酸钠脱胶的精干麻的结晶度小于过碳酸钠脱胶的精干麻结晶度；但是,碱性果胶酶-过碳酸钠脱胶的精干麻果胶含量和残胶率下降,脱胶更加彻底,故精干麻的断裂强度和柔软度都得到提高。为了进一步降低精干麻中半纤维素的含量和精干麻的残胶率,降低过碳酸钠脱胶工艺中过碳酸钠的用量,减少纤维素损伤,提高产品质量,提高生产效率。本课题使用过氧乙酸对苎麻原麻进行脱胶前处理。实验发现,过氧乙酸-过碳酸钠脱胶的前处理最优工艺参数为：温度55℃,pH值5.0,时间为1.5h,过氧乙酸浓度为2%。根据过碳酸钠分解情况的实验结果,在过碳酸钠煮练工艺中,煮练时间减少30min,确定为120min,过碳酸钠的浓度由18%降低至12%,温度由95℃降低至90℃。实验结果表明,过氧乙酸-过碳酸钠脱胶的精干麻的断裂强度、断裂伸长率和断裂比功均高于传统化学脱胶工艺,但传统化学脱胶的精干麻的柔软度最好,为352.49捻/10cm。SEM图片和精干麻化学组成测试结果表明,过氧乙酸-过碳酸钠脱胶后包覆在苎麻原麻周围的胶质基本去除,精干麻中木质素和半纤维素也得到了有效的去除。ATR图谱分析表明,过氧乙酸-过碳酸钠脱胶的精干麻中半纤维素和木质素等胶质的含量都进一步得到降低。精干麻的化学组成实验结果也证明了这一分析结果。XRD测试结果表明,过氧乙酸-过碳酸钠脱胶的精干麻结晶度进一步降低,但是由于精干麻中果胶、半纤维素的含量进一步下降,残胶率也大幅降低,脱胶更加彻底,使得精干麻的断裂强度和柔软度得到了进一步的提高。更多还原

【Abstract】 Ramie originated in China and is known as "China grass". It is major distributed in the Yangtze River basin. At present, China accounts for90percent of the world’s ramie production. The ramie has good spinnability, wearability, as well as good prospect of development. It is a kind of fine material of textile industry. The major ingredient of ramie is cellulose. In addition to this, the ramie also has a lot of gum, for example, hemicellulose, pectin, lignin and water soluble substances and so on. These non-cellulosic substances are known as gum. These gum need to be removed before the process of spinning. The process of making the ramie fiber separated from each other is called degumming.At present, the methods of ramie degumming are retting and chemical degumming. The retting can be divided into three kinds of methods:natural fermentation, bacteria degumming and enzyme degumming. Bacteria degumming, enzyme degumming and chemical degumming improve the quality of the degummed ramie fiber of natural fermentation to a certain extent. The efficiency of the chemical degumming is high, the time is short, and the quality is stable. However, the process of the chemical degumming is long, energy consumption is large and pollution is serious. Bacterial degumming and enzymatic degumming are usually time-consuming and high-cost. What’s worse, the quality is unstable. However, the bacteria degumming and enzyme degumming just require mild conditions and produce little environmental pollution.According to the characteristics of retting and chemical degumming, the traditional chemical degumming was researched and analyzed in this subject. There are so many problems in the chemical degumming, such as the process is long, the energy consumption is large and the pollution is high and so on. To deal with these issues, the environmentally friendly peroxide—sodium percarbonate is used in the oxidation degumming of ramie. The effects of the temperature, time and dosage of sodium percarbonate on the degumming are analyzed. The experimental results showed that the optimum process of sodium percarbonate degumming was as follows:the temperature is95℃, the time is150minutes, the dosage of sodium percarbonate is18%, chelating agent (EDTA) is2%, sodium tripolyphosphate is2%, alkali penetrating agent is2%, bath ratio is1:12. The optimal case was verified in hualong hemp industry co., LTD. Anhui province and star ramie co., LTD. Hunan province respectively. The results showed that compared with the traditional degumming, the breaking strength of degummed ramie fiber treated by sodium percarbonate degumming attained the level of92percent. Moreover, the doubling of the degummed ramie fiber is better than traditional chemical degumming. XRD analysis showed that the degree of crystallinity of the degummed ramie fiber treated by sodium percarbonate degumming is less than traditional chemical degumming. Thus, the breaking strength of the degummed ramie fiber treated by sodium percarbonate is lower than traditional chemical degumming, which can be explained by the XRD result. From the SEM pictures, readers can see that the gum coated with ramie fiber was removed after the sodium percarbonate degumming. But the cellulose surface was cracked; it meant that the fiber was damaged. The Na element test results also indicated that the cellulose was damaged and oxidized cellulose and alkali cellulose was produced. ATR analysis showed that the gum was removed after the sodium carbonate degumming. But the degummed ramie fiber contained hemicellulose and lignin. The results of the chemical composition of the degummed ramie fiber test results showed that the hemicellulose was still left. The results of the COD, pH and chromaticity test results showed that sodium percarbonate degumming pollution to the environment was far less than the traditional chemical degumming.Sodium percarbonate can produce sodium carbonate and hydrogen peroxide in aqueous solution. Therefore, the research on the decomposition velocity of sodium percarbonate and hydrogen peroxide plays a very important role in improving the effect of sodium percarbonate degumming. The reader found that hydrogen peroxide could maintain relatively stable state when the temperature was70℃under zero in neutral conditions. At the same time, the decomposition velocity of hydrogen peroxide rose with the increasing of the concentration of hydrogen peroxide. Alkaline condition was preferred to neutral condition in the results of the decomposition velocity of hydrogen peroxide. When the sodium hydroxide concentration was constant, the decomposition velocity of hydrogen peroxide rose with the increasing of the concentration of hydrogen peroxide. When the hydrogen peroxide concentration was constant, the decomposition velocity of hydrogen peroxide slowed down with the increasing of the concentration of sodium hydroxide. Therefore, when the hydrogen peroxide was used to bleach the raw materials, the advisable temperature was not less than70℃advisable under the neutral condition. While in alkaline condition, using hydrogen peroxide to treat the ramie, the concentration of hydrogen peroxide was no less than6g/L; along with the concentration of sodium hydroxide was2-4%. In the process of heating, when the ramie raw materials were put into the sodium percarbonate scouring solution, the decomposition velocity of sodium percarbonate was faster that of not adding ramie raw materials to the sodium percarbonate scouring solution. To some extent, this was due to the ramie raw materials containing more dust, metal and so on; these impurities will promoted the invalid decomposition of hydrogen peroxide. At the same time, sodium percarbonate also interacted with the ramie raw materials, thus, the decomposition of sodium percarbonate was faster that of not adding ramie raw materials to the sodium percarbonate scouring solution.In addition, in the process of heating, when the temperature was below80℃and when the ramie raw material was not put into the sodium percarbonate scouring solution, sodium percarbonate could maintain more stable state. As the temperature was rising from80℃to90℃, the decomposition of sodium percarbonate was significant. However, when the ramie raw materials were put into the sodium percarbonate scouring solution, no matter how the temperature changed, the decomposition of sodium percarbonate was obvious. Moreover, when the temperature was90℃, and remained the same temperature, the concentration of sodium percarbonate was close to zero after90minutes. Therefore, when using sodium percarbonate to treat the ramie raw material, the scouring time preferably was around90minutes.In order to make the decomposition speed of hydrogen peroxide stable, avoid or reduce hydrogen peroxide invalid decomposition and oxidation degree of cellulose during the sodium percarbonate degumming, the application of stabilizer on the sodium percarbonate degumming was analyzed in this subject. The results showed that compared with the process of not using the oxygen bleaching stabilize in sodium percarbonate degumming, breaking strength and breaking elongation of the degummed ramie fiber were improved after using the oxygen bleaching stabilizer P5. The results of the Edna group Jiangxi province also showed that the performance of the degummed ramie fiber improved after using the oxygen bleaching stabilizer P5during the process of sodium percarbonate degumming.In order to reduce the amount of sodium percarbonate and the damage of cellulose during the sodium percarbonate degumming, the pectate lyase was used in the process of pretreatment on the ramie degumming in this subject. At the same time, the writer used the oxidizing and bleaching property of sodium percarbonate to treat the ramie treated by pectate lyase. And the writer combined the three processes ("inactivation","scouring" and "bleaching") of the enzyme degumming of the ramie into one process ("sodium percarbonate degumming"). After these, the aim of shortening the process and improving the production efficiency was achieved. Readers found that the requirements of optimal pretreatment process of pectate Iyase-sodium percarbonate degumming were as follows:the temperature was60℃, the time was3hours, the pectate lyase was1.0g/L and the pH was8.5. According to the experimental results of the decomposition velocity of sodium percarbonate, during the process of sodium percarbonate degumming, the writer reduced the time from150minutes to120minutes, the dosage of sodium carbonate from18%to12%and the temperature from95℃to90℃. SEM images showed that the gum was removed after the ramie treated by pectate lyase-sodium percarbonate degumming. ATR analysis indicated that the pectin of the degummed ramie fiber was removed effectively after the pectate lyase-sodium percarbonate degumming. But there were still capable of hemicellulose in the degummed ramie fiber. The test results of the chemical composition of degummed ramie fiber proved the experimental results. XRD analysis results showed that the degree of crystallinity of degummed ramie fiber treated by pectate lyase-sodium percarbonate degumming was less than that of sodium percarbonate degumming. However, the amount of the pectin and the content of residual gum of the degummed ramie fiber were all reduced, and the effect of degumming was more thoroughly, so the breaking strength and the softness of the degummed ramie fiber were improved.To further reduce the content of hemicellulose and the content of residual gum of the degummed ramie fiber, as well as the dosage of sodium percarbonate and the cellulose damage and improve the efficiency of degumming and the quality of degummed ramie fiber, the peracetic acid was used in the process of pretreatment of the ramie degumming. Readers found the requirements of the optimum process of pretreatment of peracetic acid-sodium percarbonate degumming were as follows:the temperature was55℃; the pH was5.0; the time was1.5hours and the peracetic acid was2%. According to the experimental results of the decomposition velocity of sodium percarbonate, during the process of sodium percarbonate, the writer reduced the time from150minutes to120minutes, the dosage of sodium carbonate from18%to12%and the temperature from95℃to90℃. The experimental results showed that breaking strength, breaking elongation and specific breaking work of the degummed ramie fiber treated by peracetic acid-sodium percarbonate degumming were higher than that of the traditional chemical degumming process. But the softness of the degummed ramie fiber treated by traditional chemical degumming was the best-352.49twist/10cm. SEM images show that the gum was removed after the peracetic acid-sodium percarbonate degumming. The hemicellulose and lignin were removed effectively. ATR analysis showed that the content of hemicellulose and lignin had been further reduced. The experimental results of chemical composition have also proved these results. XRD results showed that the degree of crystallinity of degummed ramie fiber had further reduced after the peracetic acid-sodium percarbonate degumming. On account of the content of pectin and hemicellulose reducing, the content of residual gum of the degummed ramie fiber was all reduced significantly. Furthermore, the effect of degumming was more thoroughly, so the breaking strength and the softness of the degummed ramie fiber were further improved.更多还原