【作者】 夏兆鹏；

【导师】 俞建勇；

【作者基本信息】 东华大学 ， 纤维工程， 2009， 博士

【摘要】 天然纤维素纤维具有良好的综合服用性能,深受广大消费者的青眯,且资源丰富,可生物降解,可循环再生,符合绿色生态和可持续发展要求,市场发展前景广阔。棉纤维是第一大天然纤维,但由于受到耕地面积、种植条件等因素的制约,其供需矛盾日益突出,迫切需要寻求新型非棉纤维素纤维资源。黄麻从产量上作为仅次于棉纤维的第二大天然纤维素纤维,具有产量大、价格低、力学性能优良等优势,同时还具有吸湿性好、抗菌性优良等优点。但由于精细化技术和纺纱技术未能取得突破,黄麻纤维还存在粗、硬、抱合力差等缺点,无法纺制细度较高的纱线,从而限制了黄麻纤维在高档纺织服装领域的应用。本文在总结前人研究成果的基础上,提出选用化学-生物联合精细化技术制备黄麻纤维。在化学法精细化研究中,以黄麻纤维细度、断裂强度、残胶率和木质素含量为指标,分析探讨了氢氧化钠和亚硫酸钠浓度、煮练时间、煮练温度及浴比对各指标的影响:在生物酶法精细化研究中,采用正交分析法计算得出了最佳生物酶浓度、处理时间和处理温度。本文采用红外光谱法和化学成分分析法对黄麻纤维成分研究表明,化学法除去了黄麻纤维中绝大部分半纤维素与部分木质素,漆酶进一步除去了黄麻纤维中的部分木质素。XRD分析表明,随着半纤维素和部分木质素成分的去除,黄麻纤维的结晶度逐步提高。化学-生物联合精细化处理后黄麻纤维的细度虽然显著提高,但仍具有弯曲刚度大、成网抱合力差等缺点,在棉型梳理机上成网困难,无法进行纺纱。因此,本文研究了黄麻纤维的纺前改性处理,通过SEM图片和FTIR图谱分析,并结合纤维摩擦系数测试结果,研究了高浓度（300g/L）和低浓度（25g/L）有机硅油试剂对黄麻纤维可绕度的作用机理,发现低浓度时硅油试剂仅存在于黄麻纤维表面,而高浓度时有机硅油不但渗透进入了黄麻纤维内部,还包覆在纤维表面,显著降低了黄麻纤维的动、静摩擦系数,纤维可绕度也显著提高。分别采用紧密纺技术和传统环锭纺技术纺制了黄麻/棉混纺纱,对比研究发现,紧密纺混纺纱的断裂强度高于相应的传统环锭纺纱,但提高并不显著;而断裂伸长率却显著提高。紧密纺混纺纱的条干、毛羽值、棉结和粗、细节等指标均优于传统环锭纱;但由于网格圈原因,紧密纺纱机无法纺制黄麻比例高于50%的混纺纱。因此,本文采用传统环锭纺纱技术纺制了黄麻比例为30%～70%的系列黄麻/棉混纺纱,并借助2参数Weibull模型预测纱线强度随隔距的变化规律。研究发现:混纺纱中的弱节数量越多,其断裂强度随测试隔距的力学衰减就越严重。纱线的断裂强度随隔距的力学衰减会降低织造效率,因此成纱过程中应着重控制和减少黄麻/棉混纺纱的细节数量。本文在研究黄麻纤维断裂强度时发现,传统2参数Weibull模型由于没有考虑到纤维直径的变异因素,而无法准确预测黄麻纤维的断裂强度,因此本文根据纤维直径变异的对数值与测试隔距对数值之间存在线性关系计算得出黄麻纤维Weibull参数γ值等于0.3474,推导出了改进的黄麻纤维Weibull强度方程为:（?）=σ₀（L/L₀）^-r/mΓ（1+（1/m））（其中m为Weibull模量,σ₀为尺度参数,L为测试隔距,L₀为单位长度,Γ为伽玛函数）。试验验证表明:改进的Weibull方程比传统的2参数Weibull方程更加精确。黄麻与棉纤维的尺度效应研究表明,棉纤维断裂强度和断裂伸长率符合传统的2参数Weibull方程,为典型的Weibull纤维。本文以改进的黄麻纤维Weibull力学方程为基础推导出黄麻/棉混纺纱断裂强度方程为:σ_y=(V_J+V_C（E_C/E_J）σ_0J(l_cJ^γ)^-1/m_Jexp（-1/m_J）cos²θ′(其中V_J、V_C分别为黄麻纤维和棉纤维的体积含量,E_J和E_C为黄麻纤维和棉纤维的模量,σ_0J为黄麻纤维Weibull特征强度,l_cJ为黄麻纤维最小破碎长度,γ为黄麻纤维的Weibull参数γ,m_J为黄麻纤维Weibull模量,θ′为纱线断裂时纤维螺旋角)。研究发现L_f/l_c比值,即纤维在混纺纱中最小破碎次数,对混纺纱的断裂强度有重要的影响:混纺纱线的断裂强度随着L_f/L_c比值的增加而增大。ln（拉伸隔距）与ln（黄麻纤维断裂伸长率）有很高的线性关系,由此推导出了纤维断裂伸长率ε_f与最小破碎长度l_c的关系为:ε_f=8.5634·l_c^-0.4343,并首次计算得出混纺纱中纤维的最小破碎长度lc。讨论分析表明:随着黄麻纤维混纺比的提高和测试隔距的增加,黄麻纤维最小破碎长度也随之提高;但由于黄麻纤维的加入使得混纺纱的CV值增大、弱节增多,导致了混纺纱中黄麻纤维断裂次数（L_f/l_c比值）减少,因而降低了黄麻混纺纱的断裂强度。更多还原

【Abstract】 The fibrics made from natural cellulose fibre have good wearability and properties such as biodegradable,renewable,eco-friendly,and sustainable.The cellulose fibre will have a bright prospects in the future.The supply of the cotton fibre can not meet the needs of textile industry in China.The output of cotton fibre can not be increased largely due to the restriction of the plantation and planting condition.Therefore,more and more novel natural cellulose fibres have been developed.Jute fibre which occupies the second place to cotton in the output has many advantages such as high output,low price,good mechanical properties,excellent moisture absorption and antibacterial properties.However,it is difficult for the jute fibres to be spun into the finer yarns because the jute also has a few undesirable properties,such as stiffness, harshness and there are no turns on the fibre.Therefore,the jute fibre can not be used for clothes.Based on the investigations of the previous researchers,chemical and enzyme treatment was the most promising method for degumming the jute fibre.For the chemical treatment,the effect on jute fibre properties by sodium hydroxide concentration,sodium sulfite concentration,treatment time,treatment temperature and liquor ratio was studied in detail.For the enzyme treatment,the concentration of enzyme,treatment time and treatment temperature were optimized by using of an orthogonal experimental design.The chemical composition and crystallinity index of jute fibre were also investigated in this paper,the results show that most of the hemicellulose and part of lignin in jute fibre was removed by the chemical treatment. The lignin content was removed further after the laccase treatment.The crystallinity index of jute fibre was increased after chemical and enzyme treatment.After the chemical and enzyme treatment,jute fibres also show prominent stiffness and harshness properties,which offer hindrance to its smooth,truble-free spinning for web and yarn making.So,jute fibre is essentially conditioned for easy spinning modification by adding oil and water.The mechanism on softness of jute fibre by silicone oil treated at 300 g/L and 25 g/L was studied by using of SEM,FTIR and fibre friction coefficient testing.The results show that for the case of 25 g/L,the macromolecule of silicone oil was only on the surface of the fibre.For the case of 300 g/L,the surface of jute fibre was covered by the thick macromolecule of silicone oil and the macromolecule of silicone oil penetrated the inner structure of jute fibre. Therefore,the dynamic and static friction coefficient of jute fibre decreased after treatment at 300 g/L which results in increasing of the softness of jute fibreThe breaking strength of compact jute/cotton yarns was slightly higher than the corresponding traditional ring blended yarns.Whereas,the breaking strain of compact jute/cotton yarns was obviously higher than the corresponding traditional ring yarns. The compact blended yarns have lower irregularities,less thin places,and smaller the number of thick places than that of traditional ring blended yarns.When there were more than 50%jute fibres in the blend,the roving could not be spun into yarn on the compact spinning frame because the perforated lattice apron is not suitable for the jute fibre.Therefore,the blended yarns with jute proportion from 30%to 70%were spun by the traditional ring spinning technology and the relationship between breaking strength and gauge length was predicted by Weibull distribution.The results show that the J70/C30 yarn decreases more sharply than the other yarns because there are more weak points in J70/C30 yarn than of the others.The tensile behaviour of the yarn at different gauge lengths is very important for practices such as warping,sizing, beaming,and weaving.So it is crucial to reduce the number of thin places in the jute/cotton blended yarns.The two-parameter Weibull distribution does not always adequately describe the experimental bast fibre strength at different gauge lengths.For this reason,it was modified by incorporating the diameter variation（Weibull parameterγ） of jute fibres in this paper.The results show that the Weibull parameterγwas equal to 0.3474 according to the slope of liner regression between ln（Coefficient of variations of fibre diameter） and ln（gauge length）.The modified Weibull distribution for jute fibre can be written as（?）=σ₀（L/L₀）^γ/mΓ（1+1/m）,where m is Weibull modulus,σ₀ is the characteristic strength,L is gauge length,L₀=1 mm,Γis the gamma function.The breaking strength of jute fibre at 2 mm,3 mm,and 4 mm gauge lengths can be predicted by the modified Weibull distribution more accurately than that of two-parameter Weibull distribution.The investigation of scale effect on jute and cotton fibre indicated that both of the breaking strength and breaking strain of cotton fibre were fit to the two-parameter Weibull distribution.The cotton fibre is so-called classical Weibull fibre.Based on the modified Weibull distribution for jute fibre,the breaking strength of jute/cotton yarn can be given by:σ_y=（V_j+V_C（E_C/E_J））σ_0J(l_cJ^?m_J)^-1/mJ exp（-1/m_J）cos²θ’ where V_J and V_C were fibre volume fraction for jute and cotton,E_J and E_C were fibre tensile modulus for jute and cotton,σ_0J and l_cJ were characteristic strength for jute and cotton,m_J was the Weibull modulus for jute fibre,andθ’ was helix angle of the fibre at the time of yarn failure.The results show that the breaking strength of jute/cotton blended yarn is determined by the level of L_f/l_c ratio:the breaking strength of jute/cotton blended yarn increases with the increasing of the value of L_f/l_c.There is a good linearity between ln（breaking strain of jute fibre） and ln（gauge length）,therefore the critical length（l_c） can be obtained byε_f =8.5634·l_c^-0.4343,where is the breaking strain of jute fibre in the blended yarn.The critical length of jute fibre increases as more jute fibres are added in the blended yarn and the critical length of jute fibre decreases with the increasing of gauge length.However,in practice,the value of L_f/l_c decreases because the increasing of thin places and CV value of the blended yarn when more jute fibre are added in the blended yarn.更多还原