PET/PT双组分弹性长丝的热收缩性能及卷曲形成机理探讨

由于纺丝线上PET/PTT复合长丝中各组分受到的纺丝张力差异导致两组分存在潜在的热收缩性差异.从纺丝线下来的成品丝只有通过后道热处理,才能有效释放潜在的热收缩差异,获得理想、可用的卷曲弹性.通过TMA测试了PET/PTT双组分复合弹性长丝及其对应单组分纤维的热收缩性能.同样的外作用力下,PET/PTT纤维的收缩应变更接近PET纤维、远小于PTT纤维.同样预张力约0.2N下,PET/PTT、PET、PTT纤维的收缩应力依次变大.结果表明PET纤维具有较小的收缩应力和较小的收缩应变,PTT纤维具有较大的收缩应力和较高的收缩应变.这导致后道热处理过程中,PTT组分发生强烈的尺寸收缩,并带动收缩较小的PET组分位于纤维外侧并形成更为细密的卷曲.     

PET/PTT双组分弹性长丝的热收缩性能及卷曲形成机理探讨

由于纺丝线上PET/PTT复合长丝中各组分受到的纺丝张力差异导致两组分存在潜在的热收缩性差异。从纺丝线下来的成品丝只有通过后道热处理,才能有效释放潜在的热收缩差异,获得理想、可用的卷曲弹性。通过TMA测试了PET/PTT双组分复合弹性长丝及其对应单组分纤维的热收缩性能。同样的外作用力下,PET/PTT纤维的收缩应变更接近PET纤维、远小于PTT纤维。同样预张力约0.2N下,PET/PTT、PET、PTT纤维的收缩应力依次变大。结果表明PET纤维具有较小的收缩应力和较小的收缩应变,PTT纤维具有较大的收缩应力和较高的收缩应变。这导致后道热处理过程中,PTT组分发生强烈的尺寸收缩,并带动收缩较小的PET组分位于纤维外侧并形成更为细密的卷曲。     

聚苯硫醚纤维的抗张强度与工艺和结构的关系

以熔融纺丝法制备出不同结晶度的各向同性聚苯硫醚纤维作为样品,根据密度和声速测定值确定出PPS晶相和无定形相的本征横向声模量E0⊥,c(4.40 GPa)和E0⊥,am(1.99 GPa).利用密度梯度法测定出的结晶度Xc和X-衍射法测定的晶区取向因子fc,按照Samules模型计算出不同牵伸和定型工艺下制备的PPS纤维样品的非晶区取向因子(fam),在此基础上分析PPS纤维抗张强度与牵伸定型工艺参数、结构之间的关系.结果表明,PPS纤维的最佳牵伸温度及紧张热定型温度分别在90℃和190℃附近;提高PPS纤维的牵伸温度及紧张热定型温度可以增加纤维的结晶度,在一定范围内对纤维抗张强度的增加有促进作用;但较高的牵伸温度及紧张热定型温度不利于纤维非晶区取向的提高,造成PPS纤维抗张强度降低.牵伸倍数的增加可以有效提高PPS纤维的非晶区取向程度,抗张强度也随着增加.     

不同纺速PET纤维的红外光谱

用红外光谱研究了纺速对PET纤维结晶度和取向度的影响。发现PET纤维的结晶度和取向度随纺速的增加而增加,且结晶度和取向度与纺速的关系曲线的斜率都在纺速3300m/min处出现明显改变。表明纺速低于3300m/min的纤维随纺速增加以增加纤维的取向度为主,而高于3300m/min的纤维则以增加结晶度为主。认为纺速为3300m/min的PET纤维中中介态趋于饱和,因而易于诱发结晶。X-射线衍射与DSC测试结果均与此相符。     

不同纺速PET纤维的红外光谱

用红外光谱研究了纺速对PET纤维结晶度和取向度的影响。发现PET纤维的结晶度和取向度均随纱速的增加而增加,且结晶度和取向度与纺速关系曲线的斜率都在纺速3,300m/min处出现明显改变。表明纺速低于3,300m/min的纤维,随纺速增加以增加纤维取向度为主,而高于3,300m/min的纤维,则以增加结晶度为主.认为纺速为3,300m/min的PET纤维中中介态趋于饱和,因而易于诱发结晶。X射线衍射及DSC测试结果均与此相符。     

聚丙烯腈纳米纤维的高效制备及结晶取向性能

分别采用传统静电纺丝装置和自行搭建的离心-静电纺丝装置制备出聚丙烯腈(PAN)纳米初生纤维,并在热空气浴中和一定外力作用下进行牵伸,牵伸后使其伸长至原长的1倍到3倍.通过广角X射线衍射(WAXD)、扫描电子显微镜(SEM)等方法对2种纺丝方法制备的PAN纳米初生纤维及经过热空气浴牵伸后的PAN纳米纤维的晶态结构、取向及形貌等进行了表征.研究表明:(1)离心-静电纺丝效率远高于静电纺丝,可达静电纺丝的120倍(离心-静电纺丝纺丝液流速为2 m L/min,静电纺丝纺丝液流速1 m L/h);(2)无论是离心纺丝还是静电纺丝制得的纳米初生纤维结晶度均很低(离心纺丝为25%,静电纺丝为10.1%),但离心纺丝制得的纳米初生纤维有一定的取向(60.5%),而静电纺丝基本没有;(3)经过热空气浴牵伸后,2种纺丝方式制得的纳米纤维结晶度均有所提高(分别为45.8%和36.2%),取向度也有所提高(分别为72.5%和59.8%),随着牵伸温度的提高和牵伸应力的增大,纤维的平均直径不断减小(离心纺丝由675 nm降至510 nm,静电纺丝由460 nm降至355 nm).纳米纤维在制备过程晶态结构及取向的效果有限,但通过热空气浴牵伸可以使晶态结构及取向得到进一步完善.     

可调制润湿性和力学性能的电纺纤维膜的制备与性能研究

采用静电纺丝技术分别制备了无规排列和高度取向排列的聚对苯二甲酸乙二醇酯(PET)和PET/CA(柠檬酸)4种纤维膜,对它们的润湿性能和力学性能进行了研究,同时研究了纤维膜厚度对膜的力学性能的影响.研究结果表明,与无规排列的PET纤维膜相比,取向排列的PET纤维膜沿纤维取向方向的力学性能有了很大的提高,而断裂伸长率略有下降;加入柠檬酸(CA)后,PET/CA复合纤维膜的表面水接触角从132.3!减少到0!,且取向排列的纤维膜比无规排列的纤维膜更易润湿;无规排列的复合纤维膜的力学性能因加入CA而大幅下降,取向排列的PET/CA纤维膜沿纤维取向方向的力学性能下降较小,而无规排列的PET/CA纤维膜的断裂伸长率从284.1%增加到444.5%.无规排列纤维膜的力学性能随膜厚度的增加先提高,后来又下降,而取向排列的纤维膜沿纤维取向方向的力学性能随膜厚度增加而单调增加.     

静电纺聚丙烯腈纳米纤维晶态结构及取向的形成

采用新型流动水浴收集方式制备出连续单向排列的静电纺聚丙烯腈(PAN)纳米初生纤维,收集静电纺丝不同阶段的静电纺PAN纳米纤维,并在热水中进行后牵伸,使其伸长至原长的2倍、3倍.通过扫描电子显微镜(SEM)、广角X射线衍射(WAXD)等方法对静电纺丝过程不同阶段的PAN纳米纤维的形貌、直径、致密性、晶态结构及取向进行了表征.研究表明,(1)在静电纺丝过程中PAN纺丝液射流受到牵伸作用,静电纺PAN纳米纤维的晶态结构形成并逐渐完善.纳米纤维的直径随着静电纺丝过程逐渐减小(从664 nm减小至353 nm),结晶度从42.55％增加至47.76％,晶区取向由37.48％提高至43.93％.纳米纤维致密性也逐渐提高(密度由1.1917 g/cm3增加至1.1943 g/cm3).(2)静电纺丝过程进入PAN射流溶剂含量较低的阶段后,继续通过静电纺丝过程提高纳米初生纤维晶态结构及取向的效果很有限,而通过热水后牵伸过程可进一步使晶态结构及取向得到有效果的完善.研究同时发现,静电纺初生纤维的晶态结构及取向与其在热水牵伸过程中的进一步完善具有相关性.     

取向对聚左旋乳酸/聚右旋乳酸复合物纤维结晶性能的影响

通过熔融纺丝的方法制备了PLLA/PDLA复合物初生纤维,在60℃拉伸获得高取向的牵伸纤维.采用X-ray散射为主要表征手段,结合差示扫描量热(DSC)、扫描电子显微镜(SEM)以及傅里叶变换红外光谱(FTIR)等技术,系统研究了不同初始结构的PLLA/PDLA复合物纤维在不同温度下的结晶行为,重点阐明了取向对PLA复合物纤维结晶结构的影响.结果表明,取向促进复合物纤维中立构晶的形成;将纤维升温至200℃停留3 min后,再进行降温,降温过程中,高度取向的牵伸纤维只有立构晶形成,而初生纤维则在150℃左右出现α晶,表明纤维中取向的立构晶会抑制α晶的形成.综合实验结果发现,通过低温牵伸初生纤维,然后高温(α晶熔点以上)退火,可制备出高取向且具有高立构晶含量的PLLA/PDLA复合物纤维.     

异相成核和拉伸诱导对生物基PHBV复合纤维结晶结构与力学性能的影响

采用熔融纺丝法制备了聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(PHBV)/二硫化钨(WS_2)复合纤维.利用示差扫描量热仪(DSC)、热台偏光显微镜、二维广角射线衍射仪(2D-WXRD)、纤维强力仪研究了WS_2异相成核作用和牵伸诱导作用对纤维的结晶结构和力学性能的影响.研究表明,WS_2显著提高了PHBV的结晶温度,当使用2 wt%WS_2时,复合材料的结晶温度提高到115~130oC,比纯PHBV(99~105oC)提高了约25oC.WS_2不仅没有影响PHBV球晶的径向生长速率,且明显提高了PHBV/WS_2复合材料的晶核密度,熔体成核活性Φ由1.0降低为0.49.随着牵伸倍率和WS_2用量的增加,纤维的拉伸强度呈现出先增加后减小的趋势.当添加1 wt%WS_2并采用单向牵伸3.8倍时,纤维中的晶体取向产生了β晶结构,使复合纤维的拉伸强度由纯PHBV的37 MPa提高至155 MPa,断裂伸长率由2.4%增加至45%.     

Fiber structure development in high‐speed melt spinning of poly(trimethylene terephthalate) (PTT)—On‐line measurement of birefringence

To investigate the mechanism of fiber structure development for poly(trimethylene terephthalate) (PTT) in high‐speed spinning, the PTT fiber was spun with take‐up speeds from 1 to 8 km/min and simultaneously birefringence and diameter in spin‐line were measured by on‐line measurement system. The orientation‐induced crystallization of PTT fiber started to be developed at 3–4 km/min, where an abrupt decrease in diameter and an increase in birefringence appeared. The birefringence increased up to 4 km/min, decreased suddenly, and then increased gradually. The sudden decrease of birefringence at 4–5 km/min might be caused by an increase of crystalline fraction due to the fact that the intrinsic crystalline birefringence of PTT is over 10 times as low as that of PET. In WAXD images, crystalline diffraction emerged faintly at 3 km/min and distinct diffraction arcs were observed at 4–5 km/min and above. The diffraction intensity increased and the tilting angle also increased with take‐up speed. The long period structure observed in SAXS pattern started to emerge at 6 km/min, and its scattering intensity increased with take‐up speed. The long period structure was ～11–12 nm long. The cold crystallization temperature in DSC thermogram shifted to lower temperature and diminished due to the orientation‐induced crystallization as take‐up speed increased, but the melting temperature hardly increased unlike PBT and PET. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 847–856, 2008     

Melt-crystallization behavior and isothermal crystallization kinetics of crystalline/crystalline blends of poly(ethylene terephthalate)/poly(trimethylene terephthalate)

The melt-crystallization and isothermal melt-crystallization kinetics of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends (PET/PTT) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. Although PET and PTT in the binary blends are miscible at amorphous state, they will crystallize individually when cooled from the melt. In the DSC measurements, PET component with higher supercooling degree will crystallize first, and then the crystallite of PET will be the nucleating agent for PTT, which induce the crystallization of PTT at higher temperature. On the other hand, in both blends of PET80/PTT20 and PET60/PTT40, the PET component will crystallize at higher temperature with faster crystallization rate due to the dilute effect of PTT. So the commingled minor addition of one component to another helps to improve the crystallization of the blends. For blends of PET20/PTT80 and PET40/PTT60, isothermal crystallization kinetics evaluated in terms of the Avrami equation suggest different crystallization mechanisms occurred. The more PET content in blends, the fast crystallization rate is. The Avrami exponent, n = 3, suggests a three-dimensional growth of the crystals in both blends, which is further demonstrated by the spherulites formed in all blends. The crystalline blends show multiple-melting peaks during heating process.     

Morphology development and crystallization behavior of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends

The spherulite morphology and crystallization behavior of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) blends were investigated with optical microscopy (OM), small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS). The thermal analysis showed that PET and PTT were miscible in the melt over the entire composition range. The rejected distance of non-crystallizable species, which was represented in terms of the parameter δ, played an important role in determining the morphological patterns of the blends at a specific crystallization temperature regime. The parameter δ could be controlled by variation of the composition, the crystallization temperature, and the level of transesterification. In the case of two-step crystallization, the crystallization of PTT commenced in the interspherulitic region between the grown PET crystals and proceeded until the interspherulitic space was filled with PTT crystals. The spherulitic surface of the PET crystals acted as nucleation sites where PTT preferentially crystallized, leading to the formation of non-spherulitic crystalline texture. The SALS results suggested that the growth pattern of the PET crystals was significantly changed by the presence of the PTT molecules. The lamellar morphology parameters were evaluated by a one-dimensional correlation function analysis. The blends that crystallized above the melting point of PTT showed a larger amorphous layer thickness than the pure PET, indicating that the non-crystallizable PTT component might be incorporated into the interlamellar region of the PET crystals. With an increased level of transesterification, the exclusion of non-crystallizable species from the lamellar stacks was favorable due to the lower crystal growth rates. As a result, the amorphous layer thickness of the PET crystals decreased as the annealing time in the melt state was increased.     

Syntheses of random PET‐co‐PTTs and some related copolyesters by entropically‐driven ring‐opening polymerizations and by melt blending: Thermal properties and crystallinity

A library of random poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and seven PET–PTT copolymers has been prepared in a high throughput manner by entropically‐driven ring‐opening polymerizations of the corresponding macrocyclic oligomers. The products have been investigated by differential scanning calorimetry and wide angle X‐ray diffraction. They show that the 50:50 copolymer displays a crystalline phase. The same phase can be formed by in situ transesterification when a 50:50 mixture of PET and PTT is melt blended. Poly(butylene terephthalate) (PBT)–PET and PTT–PBT 50:50 copolymers also show crystal phases. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

PTT/PET共混体系晶体形态与结晶性能的研究

用差示扫描量热仪(DSC)、广角X射线衍射(WAXD)和正交偏光显微镜研究了聚对苯二甲酸丙二酯(PTT)和聚对苯二甲酸乙二酯(PET)共混体系的晶体形态与结晶性能.结果表明,共混体系结晶性能与PTT的含量有关.PET的加入,使共混体系的球晶尺寸减小.球晶完善性降低.当PTT含量为40wt%～60wt%时,共混物分别出现了双重熔融峰和双重结晶峰.双重熔融峰是加热过程中熔融重结晶造成的,双重结晶峰说明不完善的晶体产生的次级结晶.     

Orientierung und Titer beim Erspinnen von Fäden aus der Schmelze bei freier und erzwungener Konvektion

Zusammenfassung Für die Fadenkraft beim Erspinnen von Fäden aus der Schmelze wird die Gleichungf = k · n· S angewendet.S ist der Spinntiter in Denier. Der Koeffizientk wird aus Meßwerten in der Literatur ermittelt; er ist gemäßk = t _p ^c abhängig von der Temperatur der Polymerschmelze beim Austritt aus der Spinndüse.c und somitk fallen nach Abb. 1 mit den Strahlungsverlusten des Fadens ab. Für die Rechnung der Wärmeübergangszahl abhängig vom Spinntiter sind Gleichungen für PET und PA6 angege ben. Nach ihnen ist die dritte Potenz der Wärmeübergangs zahl zum Spinntiter umgekehrt proportional. Alle Werte von Spinnorientierung und Fadenspannung der sieben Meßreihen ordnen sich in das Modell ein. Anomalien wurden nicht festgestellt. Unter dieser Bedingung wurde die Rechnung bis zur vollen Spinnorientierung erweitert. Die Fadenkraft ist zum Spinntiter direkt, Spinnorientierung und Fadenspannung dagegen sind zu ihm umgekehrt proportional. An drei Beispielen wird der Zusammenhang zwischen Spinnorientierung und Fadenspannung nachgewiesen. Hierzu werden die Rechenwerte für die volle Spinnorientierung und Fadenspannung sowie die in der Literatur veröffentlichten Meßwerte eingesetzt. Ein Quotient Fadenkraft/Spinnorientierung ist für PET bzw. PA6 erforderlich, um den Spinntiter zu ermitteln, der jeder Meßreihe für die volle Spinnorientierung zugeordnetist. Die Fadenkraft beträgt für den Elementarfaden bei PET, Meßreihen 1 bis 5 einheitlich 215,75 dyn und 301,56 dyn bei PA6, Meßreihen 6 und 7. Für alle sieben Meßreihen hat sich für die Wärmeübergangszahl der gleiche Werta = 216,68-10^–4 cal/cm² s °C ergeben. Der Spinntiter für die freie Konfektion liegt bei voller Spinnorientierung und PET zwischen 0,865 den, Meßreihe 1, und 1,386 den, Meßreihen 2, 3, 4, und bei PA6 zwischen 0,982 den, Meßreihe 6, und 1,907 den, Meßreihe 7. Für die erzwungene Konvektion, PET, Meßreihe 5 ist der SpinntiterS = 5,034 den bestimmt worden. Er liegt höher als die bei freier Konvektion gerechneten Werte. Herrn Prof. Dr.F. Horst Müller in Marburg-Marbach spreche ich auch an dieser Stelle meinen verbindlichen Dank für das stets fördernde Interesse an dieser Arbeit aus.

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Summary The equationf = k · n · S is utilized for the fibre strength during spinning from the melted mass.S is the spinning titer in denier. The coefficientk is determined from measuring values in literature and is according to equation [2] and figure 1, dependent on the temperature of the polymere mass, coated during extrusion from the spinning jet. It reduces with the radiation losses of the fibre. For the calculation of the heat transmission coefficient, dependent on the spinning titer, equations are given for PET and PA6. Based on these the cubic number of the heat transmission coefficient is in reverse proportion to the spinning titer. All values from spinning orientation and fibre tension of the seven series of measurements are in sequence in the model. No anomalies were established. Under these conditions the calculation was expanded to full spinning orientation. The fibre strength is in direct proportion to spinning titer, the spinning orientation and fibre tension on the other hand in reverse proportion. The connection between spinning orientation and fibre tension are proven on three examples. For this the calculations for full spinning orientation and fibre tension was used in addition to measuring values published in literature on the subject. A quotient fibre strength /spinning orientation is required for PET or PA6 respectively, in order to determine the spinning titer assigned to each series of measurements for full spinning orientation. The fibre strength for the elementary fibre for PET is in the measuring series 1 to 5 215,67 dyn throughout and 301,56 dyn in PA6, measuring series 6 and 7. The heat transmission coefficient for all seven tests resulted in the same value = 216,68 .10^–4 cal/cm² s °C. The spinning titer for free convection lies at full spinning orientation and PET between 0,865 den measuring series 1 and 1,386 den measuring series 2, 3, 4 and with PA6 between 0,982 den measuring series 6 and 1,907 den measuring series 1. The spinning titer S = 5,034 den was then determined for forced convection PET measuring series 5. This lies higher than the values calculated for free convection.

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Mit 1 Abbildung und 4 Tabellen     

Thermal and spectroscopy studies on ternary miscibility and phase behavior in blends comprising poly(4‐vinyl phenol) and two aryl polyesters

Thermal analysis and Fourier transform infrared spectroscopy characterizations were performed on three ternary blend systems that comprise poly(4‐vinyl phenol) (PVPh) and any two of the three homologous aryl polyesters [poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT)]. Although PVPh is miscible with any one of the polyesters in forming a binary blend system, miscibility in ternary systems by introducing one more polymer of different structures to the blend system is not always expected. However, this study concludes that miscibility does exist in all these three ternary blends of all compositions investigated. Reasons and factors for such behavior were probed. Quantitative interactions in the ternary blend system were also estimated. The overall interaction energy density (B) by analysis of melting point depression for the PBT/PVPh/PET ternary blend system led to a negative value (B = −5.74 cal/cm³). Similarly, T_g‐composition analyses were performed on two other ternary blend systems, PET/PVPh/PTT and PTT/PVPh/PBT. Comparison of the qualitative results showed that the interaction energy densities in the other two ternary blend systems are similarly negative and comparable to the PBT/PVPh/PET ternary blend system. The Fourier transform infrared spectroscopy results also support the qualitative findings among these three ternary blend systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1339–1350, 2006     

Dynamics of hot-tube spinning from crystallizing polymer melts

Computer modeling is applied to discuss hot-tube effects in melt spinning from crystallizing polymers. The set of spinning equations used in the model accounts for stress-induced crystallization, crystallinity-dependent melt viscosity and heat of crystallization. Example computations are performed for polyethylene terephthalate assuming temperature-dependent Newtonian viscosity, strongly modified by crystallization. The consequence of coupling of stress-induced crystallization and crystallinity-controlled solidification is limited range of spinning speeds, and multiple solutions of the dynamic equations of spinning. The range of admissible spinning speeds and multiple (amorphous and crystalline) solutions is strongly affected by the hot-tube temperature.It is predicted that zone heating, with temperatures above glass transition (hot tube), results in considerable increase of amorphous orientation factor for moderate take-up speeds. In the high speed spinning range, the orientation effects saturate and does not exceed the values predicted for high-speed room-temperature spinning. Application of the hot tube is also predicted to reduce considerably take-up stress.Available experimental data on amorphous orientation in PET fibers spun by hot-tube technique are in qualitative agreement with the model predictions.     

Raman spectroscopic study of the effect of take-up speed on conformation,orientation, and crystallinity in PET fibers

The dependence of the Raman spectrum of PET fibers on take-up speed (TUS) during high-speed spinning is examined. It is found that conformational change, orientation, and crystallinity, all different functions of TUS as a processing variable, are reflected in the spectra. The data, as well as those from thermal annealing of PET fibers, are shown to be consistent with those from other techniques, leading to a set of equations from which a number of properties of the PET fibers can be determined from the Raman spectrum alone.