【作者】 贾曌；

【导师】 杜善义；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2008， 博士

【摘要】 近年来,运用生物技术用天然蛋白对合成纤维进行改性或修饰,开发研制多种差别化新型纤维成为国内外研究热点。聚丙烯腈纤维是合成纤维的一种,外观蓬松、柔软,有良好的弹性与保暖性。但由于它是疏水性纤维,吸湿性差、易起静电,其穿着舒适性远远不及羊毛,从而限制了它的进一步发展。本论文首次提出用蛋白质对聚丙烯腈纤维进行表面接枝改性的机制:聚丙烯腈纤维的蛋白质表面接枝改性由聚丙烯腈纤维的水解、酰氯化及与蛋白质的接枝反应三部分组成。通过水解将聚丙烯腈纤维表面的氰基极性基团(–CN)转化为成羧基基团(–COOH),从而为酰氯化提供条件。通过羧基与氯化亚砜之间的酰氯化反应,赋予纤维以酰氯强极性基团(–COCl),这是实现聚丙烯腈纤维与蛋白质接枝的基础。接枝是通过酰氯基团与蛋白质中的氨基(–NH2 )和羟基(–OH)发生不可逆氮酰化和酯化反应实现的。首次用大豆分离蛋白和豆浆实现了聚丙烯腈纤维的蛋白质表面接枝改性,揭示了各工艺条件对接枝率的影响规律,分析了接枝纤维的结构和形态,并对其回潮率、吸水率、抗静电性、力学性质、热稳定性等性能等进行了研究。以豆粕为原料,通过碱提酸沉法制备大豆分离蛋白的最佳浸提工艺条件为:浸提温度50℃、pH值10.0、固液比1:10,浸提时间50min,在此条件下,大豆分离蛋白的提取率为79.36%。聚丙烯腈纤维的水解过程与水解时间、氢氧化钠浓度和温度都有关系。研究发现当水解条件为:氢氧化钠浓度为14%,水解温度80℃,水解时间为l5 min时接枝效果最好。水解导致纤维表面刻蚀、裂缝和空洞,从而引起纤维断裂强度和断裂伸长的降低。但是接枝大豆分离蛋白可以较好地弥补因纤维水解而产生的表面损伤和力学性能下降等缺陷,使力学性能得到相应修复。当氯化亚砜加入量约占接枝纤维质量的10%,反应温度为110℃,反应时间为30min时,可以获得接枝率较高的蛋白质接枝改性聚丙烯腈纤维。接枝反应研究结果表明:在浓度为10%的氢氧化钠加入量为1.0mL、反应温度80℃、反应时间3min条件下,能够获得较好的接枝效果。对蛋白质接枝改性聚丙烯腈纤维进行了FTIR、XRD和SEM分析,结果表明:接枝改性聚丙烯腈纤维分别在1630cm-1和1530 cm-1处新增蛋白质酰胺I带和酰胺Ⅱ带的特征吸收峰,在3400cm-1左右处新增蛋白质羟基特征吸收峰;同时,原样聚丙烯腈纤维2243 cm-1处氰基特征吸收峰的强度明显降低。蛋白质接枝改性聚丙烯腈纤维分别在2θ=16.8?处有强衍射峰,在2θ=29.5?处有相对较弱的衍射峰,在2θ= 17~29?之间发生漫散射,基本保持了原有聚丙烯腈纤维的高序态和低序态共存的聚集态结构特征。接枝改性聚丙烯腈纤维表面覆盖着完整致密的蛋白质表面膜层。聚丙烯腈纤维经蛋白质表面接枝改性后,由于大分子中羧基、羟基、氨基等极性基团的大量存在,纤维的回潮率由接枝前的2%提高到5.2%,吸水率由接枝前的12.5%提高到23.6%,质量比电阻由接枝前的1.91×109?·g/cm2下降到4.63×108?·g/cm2,蛋白质接枝改性聚丙烯腈纤维的吸湿性、吸水性和抗静电性都得到明显提高,大大提高了服用纤维的穿着舒适性。同时,聚丙烯腈纤维经过蛋白质表面接枝改性后,虽然断裂强度、断裂伸长率、起始失重温度和残余质量有微降,但总的来说,纤维固有的强伸性质和热稳定性基本保持不变。更多还原

【Abstract】 In recent years, more and more researchers have focused on the modification of the chemical fiber with natural protein. Polyacrylonitrile fiber, for its relatively cheap price and other important characteristics, such as soft, wool-like hand, good antibacterial property and excellent resistance to sunlight, is widely used in the textile industry. But Polyacrylonitrile fiber is hydrophobic and exhibits some obvious disadvantages, such as low moisture-absorbency and electrostatic tendency, which greatly limits its further applications.For the first time, the mechanism of grafting of protein onto the Polyacrylonitrile fiber was proposed. The grafting modification consists of three parts: (1) hydrolysis of the original Polyacrylonitrile fiber; (2) chlorination of the hydrolyzed Polyacrylonitrile fiber; (3) grafting of protein onto the chlorinated Polyacrylonitrile fiber. The nitrile group–C≡N in Polyacrylonitrile fiber is converted to carboxyl group–COOH after hydrolysis in NaOH aqueous solution.Afterwards, chloroformyl group–COCl is obtained when carboxyl group is treated with SOCl2. Finally, nitrogen acylation and esterification are carried out when chloroformyl group reacts with amino group–NH2 and hydroxyl group–OH of the protein which provides the chemical fiber with protein on its surface. A novel chemical modification method of Polyacrylonitrile fiber was first introduced by grafting of natural protein-soy protein and soybean milk, separately, onto the surface of Polyacrylonitrile fiber. The effects of the production procedures on grafing efficiency were systematically investigated and the grafting conditions were optimized. The structures and morphologies of the protein grafted fiber, such as moisture absorption, water retention, specific electric resistance, mechanical properties and thermal tolerance were characterized.Using the bean dregs as the raw material, the technological condition of extracting soy protein isolate was optimized through alkali extraction and acid precipitation technique with the leaching solution pH value, 10.0; extraction temperature 50℃; feed-liquid ratio, 1:10 and leaching time, 50min. At this condition, protein extraction rate was 79.36%. The hydrolysis of Polyacrylonitrile fiber was affected by hydrolysis time, hydrolysis temperature and concentration of NaOH. To make the protein modified Polyacrylonitrile fiber in this study, the best hydrolysis conditions were: NaOH concentration 14%, hydrolysis temperature 80℃and hydrolysis time 15 min. Grafting modification could make up the decrease of the mechanical properties due to the surface erosion during the hydrolysis reaction.Chlorination reaction made the grafting of protein onto Polyacrylonitrile fiber possible by providing the active chloroformyl group. In this study, ten gram of hydrolyzed Polyacrylonitrile fiber was first treated with 1.0 mL of SOCl2 at 110℃for 30 min during the chlorination reactions and then put into 1.0 mL of 10wt % NaOH aqueous solution at 80℃for 3min for the grafting of protein onto the surface of the Polyacrylonitrile fiber. After these procedures, the protein was grafted onto the Polyacrylonitrile fiber with a proper grafting efficiency.FT-IR spectra have presented that some new amide group I andⅡband peaks appeared at 1530 cm-1and 1630cm-1 respectively. Meanwhile, new carboxyl group appeared at 3400cm-1. The intensity of these new peaks increased with the increasing grafting efficiency while the intensity of the original nitrile group at 2243 cm-1 decreased greatly, which indicated the presence of protein in the modified fiber through the reactions of nitrile group. X-ray diffraction showed that the protein-modified Polyacrylonitrile fiber showed an intense reflection at about 16.8? and another sharp peak at about 29.5? and a broad diffuse reflection between the two sharp peaks. The characteristic feature of the XRD pattern of protein-modified Polyacrylonitrile could be described by the classical crystalline and amorphous structure model for semi crystalline polymers. SEM micrographs have confirmed that the surface of protein modified fiber was covered by integrated and compact protein film.With protein grafting modification, the moisture absorption was increased from the original 2.0% up to 5.2%. This grafting modification leaded the water retention from 12.5% of the ungrafted Polyacrylonitrile fiber up to 23.6%. The specific electric resistance was decreased from 1.91×109?·g/cm2 to 4.63×108?·g/cm2. Compared with ungrafted fiber, the protein modified Polyacrylonitrile fiber showed much better moisture absorption, water retention and antistatic property which resulted from the fact that plenty of polar groups, such as carboxyl group, amino group and hydroxyl group, etc. Though there was a little decrease of the breaking strength, breaking elongation, stating weight loss temperature and residual mass after surface grafting modification, generally speaking, the modified fiber still exhibited good mechanical properties and thermal stability which could meet the requirement of textile production and wearing.更多还原