热处理对杂环芳纶结构与性能的影响

采用了热失重分析仪(TGA)、傅里叶变换红外光谱(FTIR),扫描电子显微镜(SEM),广角X射线衍射(WAXD)等手段研究热处理对含杂环的共聚芳香族聚酰胺纤维结构与性能的影响。结果表明:热处理条件为氮气气氛,温度420℃,时间4 min,拉伸倍数为1;经过热处理后杂环芳纶的化学结构没有明显的变化,纤维结晶度由11.2%提高到51.6%,纤维的取向度显著提高,纤维的表面更加光滑致密;纤维的热稳定性无明显变化,纤维的线密度有略微变小,断裂强度为23.8 cN/dtex,弹性模量为1 041.43 cN/dtex。     

硼酸改性PAN原丝提高预氧化纤维的均质化程度

利用硼酸浸渍PAN原丝,然后进行原丝预氧化,最后制得了致密化程度高的预氧化纤维。利用扫描电子显微镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)对预氧化纤维的形貌、结构和结晶度进行了分析研究。研究表明,硼酸改性能降低环化度,提高致密化程度,从而获得均质的预氧化纤维。     

聚甲醛纤维制备工艺及其性能的研究

以聚甲醛(POM)切片为原料,在200～210℃进行熔融纺丝制得POM长丝。利用DSC、Olympus偏光显微镜、单纱电子强力仪测定了POM纤维结晶度、熔点、取向度和纤维的机械性能;研究了后处理对POM纤维性能的影响以及拉伸对POM纤维耐酸碱性能的影响。结果表明:(1)POM纤维耐碱性良好,拉伸可以提高POM纤维结晶度、取向度、断裂强度以及耐酸性,但是使断裂伸长率减小;最佳拉伸温度在110℃左右,拉伸倍率在6～8之间。(2)热定形温度对POM纤维结晶度和熔点影响不大,延长热定形时间使POM结晶度、熔点降低;最佳热定形条件为在140℃下热定形4min。(3)经过拉伸热定形后的POM纤维的最大断裂强度和断裂伸长率分别为7.41cN/dtex和19.2%。     

PMMA/PET共混体系可纺性及纤维的结构与性能

研究了PMMA/PET共混纤维的可纺性和拉伸性,并测定了拉伸丝的力学性能、取向和结晶结构。结果表明,PMMA的加入可以延迟PET的成形,减小纤维的取向,提高PMMA/PET卷绕丝的断裂伸长,从而提高纤维的后拉伸倍数,提高纤维的生产效率;PMMA的加入量在5％以下时,不影响纤维的可纺性;PMMA/PET共混纤维拉伸丝的强度和断裂伸长可达到常规PET纤维的要求;扫描电镜照片显示,PMMA以棒状形式分散在PET基体中,分散直径为1μm左右。     

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…     

拉伸工艺对BOPET薄膜结晶和取向的影响

采用X射线大角衍射(WAXD)法测定不同拉伸工艺的双轴取向PET薄膜的结晶和取向。测定结果表明,PET薄膜的结晶度和取向度主要决定于薄膜的拉伸温度、热定型温度和拉伸速度,PET薄膜的结晶和取向直接影响到薄膜的性能。     

微纳层叠挤出技术对聚氯乙烯结晶性能的影响

采用Moldex3D软件对自主发明设计的微纳层叠装置剪切场进行分析,发现沿着挤出方向,剪切速率先升高后降低;利用微纳层叠装置在挤出过程中对聚合物熔体产生的持续剪切作用,制备了1层、9层、81层3种具有不同层数的聚氯乙烯(PVC)片材。通过超声波测试、傅里叶变换红外光谱分析、万能试验机试验分别对PVC片材的取向度、相对结晶度和力学性能进行了研究。结果表明,沿挤出方向9层、81层试样的取向度比1层试样分别提高了9.82%,15.08%;9层、81层试样的相对结晶度比1层试样分别提高了4%,5.9%;挤出方向拉伸强度分别提高了11.15%,26.16%。     

PMMA／PBT共混体系可纺性及纤维的结构与性能

研究了PMMA／PBT共混纤维的可纺性和拉伸性，并测定了拉伸丝的力学性能、取向和结晶结构。结果表明，PMMA的加入可以延迟PET的成形，减小纤维的取向，提高PMMA／PBT卷绕丝的断裂伸长，从而提高纤维的后拉伸倍数，提高纤维的生产效率；PMMA的加入量在5％以下时，不影响纤维的可纺性；PMMA／PBT共混纤维拉伸丝的强度和断裂伸长可达到常规PET纤维的要求；扫描电镜照片显示，PMMA以棒状形式分散在PET基体中，分散直径为1μm左右。     

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。     

高低黏PET并列复合纤维的制备与性能

以两种不同特性黏度的聚对苯二甲酸乙二醇酯(PET)为原料,利用复合纺丝技术,一步法制得并列复合全拉伸丝(FDY)。采用声速法、差式扫描量热法等测试手段,分析了纺丝、热定形工艺对并列复合FDY的声速取向因子和结晶度下降,断裂伸长率增大,断裂强度减小,纤维的卷曲性能变好;随着热定形温度的升高,纤维的声速取向因子和结晶度增大,断裂强度提高,纤维的断裂伸长率和卷曲性能下降。     

热处理温度对涤纶混纤丝结晶及取向的影响

采用由同一喷丝板生产的283 dtex／48 f多异涤纶POY为原料,在平牵机上拉伸热处理制取混纤丝,研究了拉伸和热定形温度对纤维结晶和取向的影响。结果表明:随着热盘温度和热板温度的提高,涤纶混纤丝的结晶度和晶粒取向度有所提高,在热板温度较高时,热盘温度对结晶度的影响较小。混纤丝的声速取向系数随热盘、热板温度的变化表现出较复杂的关系。     

Creep deformation and its correspondence to the microstructure of different polyester industrial yarns at room temperature

The room temperature creep behaviors and related microstructural changes of a high‐tenacity (HT) poly(ethylene terephthalate) (PET) industrial yarn and a super‐low‐shrinkage (SLS) PET industrial yarn were investigated and compared by using wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), birefringence measurements and Fourier transform infrared spectroscopy (FTIR) in order to identify their respective underlying creep mechanisms. The crystal structure including crystalline orientation and crystallinity of fibers did not show obvious changes after the creep process, while the amorphous structures varied with creep stress. The HT yarn creep deformation was mainly elastic, and its creep recovery ratio was high. The amorphous orientation, amorphous layer thickness and degree of conformation change from gauche to trans conformers showed a slight increase. The mechanism of this slight change is that the coiled molecular chains are oriented under tensile loading and most of the extended chains are disoriented under offloading in the small amorphous region. By contrast, the SLS yarn underwent plastic creep deformation with a low recovery ratio. After the creep test, the amorphous orientation and lamellar thickness both increased but the crystallinity remained unchanged. The creep mechanism for the SLS yarn is that the molecular chains in the large amorphous domain are easily extended and oriented subjected to tensile loading, while conformation transition from gauche to trans conformers and the formation of irreversible mesophase take place. © 2018 Society of Chemical Industry     

Computer Simulation of Polyester High‐Speed Thermal Channel Spinning

A mathematical model to describe the thermal channel spinning (TCS) process in PET high‐speed melt‐spinning has been developed. This model, which is based on the spinning process kinematics, includes the effects of acceleration, gravity, and surfacial air friction. It incorporates the constitutive equation of PET polymer, the heat transfer related to the transverse air blowing and, in particular, to a convection and radiation combining procedure in the thermal channel, while taking into account the nonisothermal crystallization kinetics related to temperature and molecular orientation as well as the elongational viscosity of PET polymer connected with temperature, intrinsic viscosity and crystallinity. The developments of crystallinity, molecular orientation and morphological features of high‐speed‐spun PET fiber in the TCS process are investigated at take‐up speeds ranging from 3 600–4 400 m/min and thermal channel temperatures ranging from 160–200°C. The simulated results of this model are compared with the measured crystallinity, diameter, and birefringence of the spun yarn. The “necking point” in the TCS spinline can be predicted by this model.     

涤纶工业丝的晶态结构与性能的关系

采用广角X射线衍射(WAXD)方法分析了高强型(HT)、高强低伸型(HTLE)、高模低收缩型(HMLS)3种涤纶工业丝的晶态结构与其性能的关系。结果表明:对于断裂强度最大的HT型纤维,结晶度大(37%)、晶粒尺寸大、结晶完善程度好;对于断裂伸长率小的HTLE型纤维,晶粒尺寸较小、非晶区取向度较大(0.91),结晶区对无定形区链段运动的限制程度大;对于热收缩率小的HMLS型纤维,晶区取向度高但非晶区取向度小(0.84),高温下不易发生解取向,尺寸稳定性好。     

Study on PET fiber modified by nanomaterials: Improvement of dimensional thermal stability of PET fiber by forming PET/MMT nanocomposites

Poly(ethylene terephthalate) (PET) and PET/montmorillonite(MMT) (2.5 wt %) nanocomposites with high molecular weight were prepared by solid‐state polycondensation and their fiber was spun and drawn under various conditions. The influence of MMT nanomaterials on the thermal shrinkage of PET fiber was investigated and the structure was studied using the methods of WAXD, DSC, fiber orientation measurement, etc. The results showed that the MMT nanomaterials improved the thermal stability of microstructure of PET fiber. The fusion heat of PET/MMT was higher than that of PET, which generally implied the high orientation or high crystallinity. However, the degree of orientation and the crystallinity of PET/MMT fiber measured by WAXD were lower than that of pure PET fiber. It is suggested that the strong interaction between MMT layer and PET restricted the motions of PET molecular chains, which developed “a special continuous network structure” and prohibited the thermal shrinkage of PET fiber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2247–2252, 2005     

Correlation between tensile properties and network draw ratio for poly(ethylene terephthalate) fibers with wide range of molecular orientation and crystallinity

Poly(ethylene terephthalate) (PET) fibers with wide range of molecular orientation and crystallinity were prepared by the cold drawing of melt-spun yarns in a temperature-controlled water bath and the subsequent annealing for these samples. For all samples, the true stress-strain curves can be principally superimposed to a master curve which corresponds to the stress-strain curve for the original nonoriented amorphous yarn and it was confirmed that the original (intrinsic) network structure is not affected by molecular orientation and crystallinity significantly. Tensile properties of these fibers were studied systematically in terms of the network draw ratio which was determined as a shift factor in the matching process of a true stress-strain curve to the master curve. Consideration of the tensile drawing behavior has shown that the network draw ratio, which is defined as an extension of unique intrinsic network structure, has direct correlation with mechanical properties including the yield and breaking behaviors. When the network draw ratio is taken into consideration, PET fiber, even if it has crystallinity or molecular orientation, has appeared to behave in the manner of an almost ideal rubber during the tensile testing carried out as cold drawing. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2631–2646, 1997     

Structure–property relationship in heat-set poly(ethylene terephthalate) fibers. I. Structure and morphology

Poly(ethylene terephthalate) (PET) fibers having a range of structure and morphology were prepared by heat-setting commercial PET yarn at temperatures of 100–250°C for 5 min under two conditions, while the yarn was free to relax and when it was held taut at constant length. The crystallinity, crystallinity orientation, and crystallite size were determined by X-ray diffraction while birefringence was measured with the help of optical microscopy. The amorphous orientation factor was computed from the structural parameters. The coupling between the crystalline and amorphous regions was determined using the Takayanagi model. While crystallinity and crystallite orientation values for the corresponding samples of the free-annealed and taut-annealed series did not show very large differences, the free-annealed samples had much lower amorphous orientation, especially when heat-set at higher temperatures. Also while the free-annealed samples showed a predominantly series type of coupling between the crystalline and amorphous regions, the taut-annealed samples showed a significant degree of parallel coupling. It is shown that samples in which there is distinct phase separation between the crystalline and amorphous regions have a predominantly series type coupling.     

阻燃涤纶结构与染色及阻燃性能

对阻燃涤纶 (F RPET)的结晶度 ,取向度 ,染色性和染色前后纤维的极限氧指数进行了测试 ,并与普通涤纶进行比较 ,证明含磷阻燃剂的阻燃涤纶的结晶度、取向度均低于普通涤纶 ,染色性较普通涤纶好 ,极限氧指数大于 3 1%。     

纳米SiO2改性聚酯纺高强低伸丝的工艺研究

从原料指标对纳米SiO2改性聚酯和普通聚酯进行对比分析,发现改性聚酯的冷结晶温度、热结晶温度及结晶度等与普通聚酯存在较大差异,因此在纺制改性聚酯高强低伸工业丝时工艺应与普通聚酯有所区别。试验结果表明:通过对改性聚酯纺丝的工艺研究,采用低速多级拉伸及充分热定形,可以得到品质优异的高强低伸工业丝。