溶剂对PET纤维聚集态结构的影响

用密度法、DSC,偏光显微镜(PLM)和测定收缩率研究了1,2-二氯乙烷对不同纺速PET纤维聚集态结构的影响。结果表明,纺速不同,溶剂诱导结晶(SINC)及其动力学过程不同。高速纺纤维系取向晶态结构,对溶剂扩散有抑制作用。低、中速纺纤维基本为非晶态结构,SINC过程易于进行,但中速纺纤维取向非晶态含量高,溶胀度和收缩率较小。从而印证了关于不同纺速PET纤维结构特征的结论。     

纺程加热时纺速对PET纤维纺程上结构形成的影响

本文对涤纶熔融纺丝过程中进行纺程加热来研究纤维于纺程上结构的变化。即在不同纺速、不同加热温度等工艺条件下,测其结晶度、取向度、密度、双折射值等。研究结果表明:①纺程加热可促使PET分子在纺程上结晶,在实验的加热条件下纺速为3000米/分时是促发PET分子在纺程上开始结晶的转变速度。3200米/分以上的纺速,结晶度随纺速变化较小。纺速约为4200米/分时,纤维中达到较高的结晶度;③纺程加热不一定引起纺程结晶,只有在一定纺速下才能促使结晶的发生;③纺程加热得到的纤维以高晶区取向度,且晶区取向不随纺速变化为特征。△n值随纺速提高可增加到接近拉伸丝水平;④纺程加热得到纤维的结构有其特殊性,尚待深入研究。     

分析测试

TQ 340.720132230熔纺时X-射线在线表征纤维结构Ellison Michael S.…;Journal of Engineered Fibersand Fabrics,2008,3(3)(英)聚合物性能受其形态的影响很大。在半结晶聚合物纤维情况下,包括结晶度、结晶区的间距和排列以及聚合物链在无定形区的分子取向。从X-射线分析能获取结晶和取向的信息。在熔纺过程中,聚合物X-射线在线表征是材料特点和加工条件沿纺丝线上的结构变化及最终结构和产品的性能影响的主要信息来源。已经设计并安置一台X-射线系统,能在聚合物熔纺时作在线分析。就目前所知,该系     

冻胶纺PVA纤维拉伸及热处理

用ＤＳＣ，ＤＭＡ和声速仪等研究了热拉伸对冻胶纺ＰＶＡ纤维结构和性能的影响，观察到热拉伸过程中存在在着不同结晶相结构之间的转变，且高强高模纤维的形成与这种转变有关，本文还研究了热处理条件对冻胶纺ＰＶＡ纤维结构和性能的影响观察到加张力热处理不但能提高纤维的断裂强度和初始模量，同时还可能提高其断裂伸长率。     

冻胶纺PVA纤维的拉伸及热处理

用ＤＳＣ、ＤＭＡ和声速仪等研究了热拉伸对冻胶纺ＰＶＡ纤维结构和性能的影响，观察到热拉伸过程中存在着不同结晶相结构之间的转变，且高强高模纤维的形成与这种转变有关；本文还研究了热处理条件对冻胶纺ＰＶＡ纤维结构和性能的影响，观察到加张力热处理不但能提高纤维的断裂强度和初始模量，同时还可能提高其断裂伸长率。     

分析测试

974300利用内在的荧光在线测定PET纤维无定形取向Clauss B.…;Chemieal Fibers International,1996,46,(3/96),p .175一177(英)为评估PET非晶区分子链的平均取向,研究人员研究了内在荧光在在线测定中的用处。实行在线测定需要改进非在线测定用的仪器。改进的装置获得施油器以上20cm丝汇合处PET纤维无定形取向的量度。结果指出,当应力导致纤维中发生结晶作用时,因为无定形区高度取向链形成晶体无定形取向增加达到稳定。当拉伸比对所有卷绕速度都恒定时,由于结晶度增加的结果,无定形取向随卷绕速度增加而降低。(张桂水)荧光在线测定聚对…     

不同纺速PET纤维的结构特征及其结构转变

本文用密度法,DSC、X射线衍射研究了PET纤维的纺速对结晶度和其他结构参数的影响,发现结晶度和某些结构参数在纺速3300m/min下出现不连续变化,预示该中速纺的纤维容易诱发结晶。通过分析该中速纺纤维在低于T_g的不同温度下于定长(受约束)和不定长(可自由松弛)下热处理后各结构参数的相互关系,探讨了其结晶机制,说明其容易诱发结晶的原因是中介态含量接近饱和状态。     

PET和PTT及PET/PTT复合纤维结构研究进展

概述了聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丙二醇酯(PTT)的结构异同点,以及高速纺丝工艺条件下纤维的超分子结构。PET和PTT纤维都只存在三斜晶系晶型,均属可高速纺拉伸诱导取向结晶类纤维。随着纺丝速度的增加,在纺丝速度为4000m/min左右时,PET和PTT纤维均出现取向诱导结晶现象,且晶体尺寸增大;双折射值则先增大后减小,但在相同的纺丝速度下,PTT初生纤维的双折射值要小于PET初生纤维的双折射值。综述了PET/PTT并列复合纤维的结构研究进展。单组分纤维和双组分纤维存在结构差异。指出应进一步研究PET/PTT并列复合纤维的结构和性能。     

聚烯烃纤维

20123115添加剂改性的聚丙烯纤维超分子结构Broda Jan…;Fibres&Textiles in Eastern Europe,2007,15(5～6),p.30(英)聚丙烯纤维改性的最普通方法包括在纤维成形阶段用物理方法将添加剂掺入聚合物中。添加剂粒子与聚丙烯熔体混合,造成纤维结构参数的变化。研究了阻燃剂和颜料的影响。通过两种机制阐明了添加剂对纤维结构的影响。对于阻燃剂遇到第一机制并且没有显示出成核能力以有利于聚丙烯结晶。形成的纤维阻然影响熔融黏度和分子取向,结果产生较多的取向结构。与阻燃剂相反,颜料表现出成核能力,这有利于聚丙烯的结晶。在纤维低速挤出     

张力拉伸对PAN纤维热稳定化反应进程的影响

在不同拉伸条件下,对聚丙烯腈(PAN)纤维进行热处理。借助傅里叶变换红外光谱、X射线衍射等表征手段,研究了PAN纤维热稳定化过程中,拉伸张力对纤维分子链聚集态结构及化学反应的影响。结果表明:PAN纤维热处理过程中,施加张力会在一定程度上影响纤维的环化反应。当热处理温度较低(180℃)时,施加张力可抑制环化反应的发生;热处理温度较高(大于200℃)时,拉伸张力有利于环化反应的发生。热处理过程中,施加张力,对PAN纤维结晶度影响较小,晶区取向和全取向度增加,晶粒尺寸增大。这是由于拉伸与温度双重作用影响了纤维的聚集态结构,导致参与环化反应的分子数量发生变化。     

Intrinsic Birefringence of γ‐Form Crystal of Nylon 6: Application to Orientation Development in High‐Speed Spun Fibers of Nylon 6

The intrinsic birefringences of the α‐ and the γ‐form crystals of nylon 6 were calculated from the atomic coordinates and the bond polarizabilities using the Lorentz‐Lorenz equation. The intrinsic birefringence of the γ‐form crystal was found to be significantly smaller than that of the α‐form crystal. Those values were applied to the evaluation of the orientation function of the amorphous phase of the nylon 6 fibers produced by the high‐speed spinning process. The molecular orientation in the amorphous phase increased to the maximum point and then decreased with the spinning speed. These results suggested that an inhomogeneous structure in the fiber was formed for the higher take‐up speed.     

Nonuniform cooling in multifilament melt spinning of polypropylene fibers: Cooling air speed limits and fiber-to-fiber variations

The cooling of the spinning stage in a commercial compact-spinning line has been studied. A rectangular fiber bundle is extruded from the spinneret and cooled by air entering from one side. The speed of the cooling air is considerably reduced through the fiber bundle. There are practical lower and upper limits for the cooling air entrance speed, corresponding to filament breakage at the leeward and windward sides, respectively. These limits are functions of the material and processing parameters. Due to the nonuniform cooling, fibers sampled at the windward side generally have higher molecular orientation, lower amorphous fraction, higher density, and higher tensile modulus and strength. For most combinations of spinning and material parameters, the structure is either bimodally oriented α-crystalline or uniaxially oriented mesomorphic at all spinneret positions. Fibers with different structure types show opposite windward/leeward side trends with regard to local order and melting behavior. The structure may be mesomorphic at the leeward side and α-crystalline at the windward side, if the average spin-line stress is close to a critical value for orientation-induced crystallization, and the air speed difference across the spinneret is large. The cooling air speed affects the spin-line stress. Hence, the fiber-to-fiber variations due to nonuniform cooling are discussed in terms of the molecular orientation in the melt and the effective time available for arranging molecules into ordered structures. © 1995 John Wiley & Sons, Inc.     

聚乙交酯纤维纺丝工艺研究

采用改变纺丝速度、拉伸工艺以及测试纤维内应力、声速值、强度值等方法对聚乙交酯(PGA)的纺丝加工工艺及纤维的力学性能进行了分析研究。结果表明:纺丝速度对PGA初生纤维的取向度几乎没有影响,后拉伸能有效提高纤维的取向度及强度。低速纺丝得到的初生纤维内应力较小,可以进行高倍后拉伸,而高速纺丝得到的初生纤维内应力较大,只能进行低倍后拉伸。适当的加温以及低速拉伸有利于得到较高强度的PGA纤维。总体来说,要得到具有较好力学性能的PGA纤维,必须采用低速纺丝、高倍后拉伸、低速拉伸相加的工艺路线。     

纺丝速度对干湿法PAN纤维形貌和结构的影响

采用在线张力仪、光学显微镜、声速仪、紫外光谱、比表面积测定仪等手段研究了干湿法聚丙烯腈(PAN)纤维制备过程中纺丝速度对纤维形貌和结构的影响。结果表明随纺丝速度的提高凝固丝条上的张力线性增大,初生纤维的全取向程度也随之增大;凝固效果没有受到速度变化的影响,没有大的孔洞缺陷生成,纤维的力学性能没有受到影响。     

聚丙烯高速纺丝工艺的研究——卷绕丝超分子结构与后加工性能的工艺控制

利用X射线衍射、DSC、双折射、密度梯度等方法探讨了在3km/min高纺速下,纺丝温度对丙纶POY的超分子结构与后加工性能的影响,对冷却条件的影响也进行了讨论。指出在280℃以下范围提高纺丝温度可以降低聚丙烯高速纺程上的流变张力,使卷绕丝的结晶度降低,结晶成分中次晶含量增加,非晶区取向度提高。采用缓慢冷却有和于提高POY的非晶区预取向。采用MI=35的聚丙烯树脂,在纺丝温度270℃和缓冷条件下可得具有优良后加工性能的丙纶POY,在414m/min速度下经加弹所得DTY的强度为41.1cN/t(?)x,伸长为34.1%,卷曲率为20%,卷曲稳定性为92%。     

细旦聚酯POY的纺丝稳定性及后加工性能

本文对3600m/min纺速下纺制的不同单丝线密度的聚酯POY的结构特征参数进行了测试分析,着重分析了细旦聚酯POY的纺丝稳定性和后加工性能。结果表明:随单丝线密度的减小,POY的纺丝稳定性变得越来越差,纺速恒定下单丝线密度的减小与泵供量一定纺速的提高对纤维结构的构成影响是等效的。合理选择POY的纺丝条件,以提高纺丝稳定性,改善POY结构,是制得质量优良的细旦聚酯拉伸丝的关键。     

Studies on the kinetics of orientation and crystallization of nylon‐66 during high‐speed melt spinning

A new way of applying on‐line experimental data and basic theory to study the mechanism of orientation of a high‐speed melt spinning process is described. The relationship of birefringence and stress for Nylon‐66 was developed to understand the phenomena in the spinning line. The value of birefringence along the spinning line was calculated by various models to predict the orientation change. By comparison of the model prediction and on‐line experimental birefringence, a suitable mechanical model to simulate the change of the profiles along the spinning line was chosen, and the structural development mechanism is discussed. The results show that the orientation mechanism of high‐speed melt spinning of Nylon‐66 is determined by deformation and deformation rate along the spinning line. For Nylon‐66, molecular and crystal orientations develop independently and are controlled by the rotation of crystals and chain segments in the deformation field. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3157–3163, 2001     

Effects of modified air quenches on the high-speed melt spinning process

A high molecular weight polyethylene terephthalate was spun into fibers in the speed range from 3,000–7,000 mpm. The effect of modifying threadline dynamics through a combination of enhanced and/or retarding air quenches on the resulting spinning performance, fiber structure, and mechanical properties was examined. Particular combinations of these threadline temperature profile modifications were shown to result in significant improvements in spinning performance and as-spun fiber structure. Extensive characterization of select fiber samples revealed higher orientation and crystallinity, larger crystal dimensions, and greater mechanical properties. These results also demonstrated the ability to provide continued improvement in fiber properties at very high take-up speeds where typically a decline is observed. It is concluded that the threadline temperature profile can be altered in such a way as to significantly enhance the resulting spinning performance and fiber structure over a wide range of take-up speeds.     

涤纶短纤维在纺程中的取向与性能研究

应用ＷＡＸＤ法、声速法、双折射法等研究了涤纶在纺丝与后加工过程中取向的形成变化及和性能的关系,以及工艺条件对纤维结构和性能的影响。结果表明,纤维非晶区取向和结晶度与纤维的刚性和柔韧性密切相关,但决定纤维力学性能的主要的结构因素是纤维的非晶区有序化程度的高低。一次拉伸主要是非晶区链段沿张力方向进行有序排列的过程,伴随生成大量晶核,导致应变结晶;热定型时结晶产生于高度取向的非晶区域,是应变结晶（取向诱导结晶）和热结晶共同作用的结果;高温机械卷曲是在机械挤压条件下的热力学控制的非晶区解取向过程     

涤纶FDY熔融纺丝模拟研究

基于熔融纺丝动力学模型及理论,建立了涤纶全拉伸丝(FDY)熔融纺丝模型。在已知工艺参数条件下,模拟了丝条温度、速度、取向和结晶在纺程上的变化。结果表明:在纺程200,700,800,1 300,1 500 cm处,模拟值与实测值误差均小于10%,该模型可用于实际生产的模拟;根据模型,获得了热辊温度及速度对涤纶FDY的取向及结晶的定量关系;随着GR1速度降低和GR1温度提高,纤维的取向度和结晶度升高;随着GR2速度增加和GR2温度提高,纤维的取向度越大,结晶度越高。