Effect of pretreatment conditions on the hydrolysis and water absorption behavior of poly(ethylene terephthalate) fibrous assembly

Poly(ethylene terephthalate) (PET) fibers are very hydrophobic and are therefore treated by alkaline hydrolysis to reduce their hydrophobicity, which not only reduces their weight but also enhances their softness, flexibility and drapability. In addition, if alcohol is used as a pretreatment agent, the form of the fibers can be changed and more benefits can be obtained from the subsequent alkaline hydrolysis treatment. Therefore various alcohols were used as pretreatment agents and their effect was investigated. Treatment with 1‐decanol leads to more weight loss of the PET fibers than treatment with the other alcohols investigated. Treatment with sodium hydroxide leads to weight loss in PET fabrics because terephthalic acid and ethylene glycol are separated by the hydrolysis of the ester group in the PET chains. Weight loss increases with increasing hydrolysis time and the reaction does not immediately reach equilibrium. The microvoids of the PET surface hold water molecules. The surface morphology of PET shows that the pretreatment reagent attacks almost the entire surface of a fiber, causing surface etching. As the surface etching progresses, it propagates inside the fiber, resulting in the formation of elongated cavities on the surface. Copyright © 2011 Society of Chemical Industry     

The fine structure of bicomponent polyester fibers

The application of alkaline hydrolysis to study the change in the fine structure of bicomponent polyester fibers as their surface is removed progressively was explored. The samples were prepared with a poly(butylene terephthalate) (PBT) sheath and a poly(ethylene terephthalate) (PET) core. The reagent used to hydrolyze the PBT was 1M NaOH in 75/25 methanol to water since it appeared to react topochemically with the fiber. The solution reacted more rapidly with PET than with PBT. Thus, when necessary to retard the weight loss of the bicomponent fibers, after a 2‐h hydrolysis with this reagent to remove PBT, it was replaced with aqueous 1M NaOH solution containing 0.1% cetrimmonium bromide. Unlike homofil PET or PBT fibers, where alkaline attack appeared to be confined to the surface and left the residue relatively smooth, the bicomponent fiber was attacked unevenly, and penetration to the PET core occurred before all the PBT at the surface was removed. Nevertheless, most of the reaction was confined initially to the PBT sheath. The tenacity and extension at break of the PBT–PET fiber passed through a maximum as hydrolysis progressed. The fall in tenacity at high weight losses is ascribed to increasing surface defects in the fiber surface. After removal of the PBT by the hydrolysis, the birefringence of the residue became progressively higher. The synergistic effect of the PBT sheath on the properties of the PET core and the possible causes of the nonuniform hydrolysis at the PBT surface are discussed. An equation is proposed that includes an interaction parameter, which can be utilized to determine which property is affected most by the hydrolysis of a bicomponent fiber. In this instance, it appears from the parameters that the order is strength > extension at break ≈ birefringence. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1163–1173, 1999     

Effects of pretreatment reagents on the hydrolysis and physical properties of PET fabrics

The effects of pretreatment reagents on the hydrolysis and physical properties of PET fabrics were investigated under various alkaline hydrolysis treatment and pretreatment conditions. Before alkaline hydrolysis, solvent treatment with pretreatment reagents, including benzyl alcohol (PET‐b) or 2‐phenyl ethanol (PET‐p), modified the structure of the PET fabric, thus affecting the hydrolysis and physical properties of the PET fabrics. Fabric weight loss increased with increasing hydrolysis time. The rate constant (k) increased markedly with increasing methyl groups in the pretreatment reagents. The activation energy (E_a) of untreated fabrics was higher than those of the treated fabrics. The crystallinity of the PET fabrics increased with increasing hydrolysis times (t) and methyl groups in the pretreatment reagents. The weight loss of PET‐b increased with increasing pretreatment temperature (T). However, the weight loss of PET‐p increased up to 100°C but decreased above 120°C. The shrinkage of all samples increased with increasing hydrolysis times (t). Shrinkage of PET‐b and PET‐p was greater than that of untreated fabrics. PET‐b displayed greater shrinkage than PET‐p because byproducts polluted the PET fibers. Both the initial and maximum water absorption of the fabrics increased with increasing hydrolysis times (t). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

涤纶短纤维差别化产品的开发和市场前景

叙述了在合成纤维短纤维试验装置上 ,使用直接纺丝、间接纺丝、复合纺丝等技术 ,开发和研制的涤纶差别化纤维产品——细旦缝纫线用短纤维 ,复合纺丝芳香纤维、涤纶超短纤维、高收缩纤维、“奇异”纤维、增白纤维、中空纤维。同时 ,也对涤纶短纤维差别化产品的市场前景进行探讨 ,认为有显性市场和潜在市场可以开拓     

舒适性聚酯纤维研究Ⅰ.添加剂含量对共混纤维碱水解性能的影响

将含有间苯二甲酸双羟乙酯 5 磺酸钠(SIPE)成分的添加剂与聚酯共混纺丝形成系列共混聚酯纤维,其碱水解行为有别于传统的聚酯纤维:在一定温度下,它的碱减量率与时间之间呈现较好的线性关系,并且取决于初始碱浓度。由于结构因素上的原因,碱减量的程度随添加剂添加数量的增加而增大,而且这种影响随处理条件如处理时间、碱浓度以及处理温度等的提高而加剧。在一定数量的添加剂(<50%)下,添加剂组分与聚酯组分间能较好地相容并成微纤状形式分散于聚酯纤维中,这种分散形式对纤维的碱处理性能有较大的影响。从碱处理后的SEM照片可以看到许多微细狭长的缝隙,它们的形成将有助于水分的快速散发。     

PET/COPET共混纤维的结构与性能研究

研究了PET/COPET共混物的流变性能,考察了纤维结构,探讨了碱水解条件对纤维的力学性能和导湿性能的影响。结果表明:PET/COPET共混物与PET的流动特性相似,但粘度较低。纤维具有中空多孔结构,微孔半径随碱水解时间延长而增大。纤维线密度和强度均随碱水解时间的延长和温度的升高而减小。经碱水解后,织物的导湿率均在98％以上。     

改性PET纤维结构和染色性能的研究

自制了两种改性 PET纤维 (MF纤维和 CDP纤维 ) ,并对其染色性能与结构的关系与 PET纤维作了比较。结果表明 ,分散性染料常压沸染时 ,MF纤维和 CDP纤维的半染时间为 9,2 2 min,饱和上染率分别约为 45 % ,40 % ,碱减量处理后 ,碱减量率最大的 CDP纤维的上染率提高了近 1倍 ,高于 MF纤维的上染率 ;而 PET纤维的上染率均远低于 MF和 CDP纤维     

Changes in dyeability and morphology of cotton fiber subjected to cellulase treatment

Unprocessed and mercerized cotton fibers were treated with commercial crude cellulase. The changes in the dyeability and structural features of the fiber due to cellulase treatment were studied. The dyeability was examined in terms of uptake of three reactive dyes and the apparent affinity of Congo Red to cotton fiber. The dyeability of the unprocessed fiber was assumed to be influenced by some impurities present in it. This fiber probably resembled polynosic fiber in molecular aggregate at a certain stage of hydrolysis. Mercerized cotton showed a similar pattern in dyeability as weight loss increased, regardless of dye species. Enzyme more easily penetrated the mercerized fiber than the unprocessed fiber. Cellulase treatment influenced the X-ray crystalline reflection pattern for the mercerized fiber but nominally influenced that for unprocessed fiber. Scanning electron micrographs revealed that cellulase treatment caused swelling of the fibrils. They also revealed that the disordered regions between the fibrils in the secondary walls were removed at low weight loss for the unprocessed fiber. The mercerized fiber at high weight loss had large cracks oblique to the fiber axis and showed no individual fibrils in the secondary wall. The primary wall was removed in the initial stage of hydrolysis for both the unprocessed and mercerized fibers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 155–164, 1997     

Grafting of acrylamide–methacrylic acid mixture onto poly(ethylene terephthalate) fibers by azobisisobutyronitrile

The chemical grafting of acrylamide-methacrylic acid (AAM-MAA) mixture onto poly(ethylene terephthalate) (PET) fibers using azobisisobutyronitrile as a chemical initiator was investigated. The use of MAA as a comonomer increased the amount of AAM introduced to the PET fiber up to 33.0%, while the grafting of AAM onto fibers alone gave low graft yields. This synergistic effect was found to be at its highest when an AAM-MMA mixture having 30 wt % AAM was used. The grafting increased dyeability with both acidic and basic dyes, and increased diameter and decreased the density of the fibers. The thermogravimtric analysis results revealed that the decomposition temperature of the fibers decreased with grafting. The electron micrographs showed that grafting changed the surface morphology of the fiber and a shell-like heterogeneous structure occurred at the surface at high graft yields. © 1996 John Wiley & Sons, Inc.     

原位聚合法生产全消光聚酯的技术探究

在自主研发的功能性纳米TiO2母液中加入乙二醇,经稀释、离心和接地消除静电后,通过在线添加技术注入酯化釜后低聚物管线注射系统,经原位聚合制得全消光聚酯(PET)及纤维。与半消光PET及其他常规PET产品系列的制备工艺相比,全消光PET制备宜采用较低的反应温度,并通过调整终缩聚真空度来控制产品的黏度。与功能母粒添加法相比,原位聚合法制得的全消光PET产品及其纤维的质量更稳定,尤其是染色均匀性更好,产品优等品率提升5.6%。     

Superfine structure,physical properties,and dyeability of alkaline hydrolyzed soly(ethylene terephthalate)/silica nanocomposite fibers prepared by in situ polymerization

In this study, poly(ethylene terephthalate) (PET)/SiO₂ nanocomposites were synthesized by in situ polymerization and melt‐spun to fibers. The superfine structure, physical properties, and dyeability of alkaline hydrolyzed PET/SiO₂ nanocomposite fibers were studied. According to the TEM, SiO₂ nanoparticles were well dispersed in the PET matrix at a size level of 10–20 nm. PET/SiO₂ nanocomposite fibers were treated with aqueous solution of sodium hydroxide and cetyltrimethyl ammonium bromide at 100°C for different time. The differences in the alkaline hydrolysis mechanism between pure PET and PET/SiO₂ nanocomposite fibers were preliminarily investigated, which were evaluated in terms of the weight loss, tensile strength, specific surface area, as well as disperse dye uptake. PET/SiO₂ nanocomposite fibers showed a greater degree of weight loss as compared with that of pure PET fibers. More and tougher superfine structures, such as cracks, craters, and cavities, were introduced, which would facilitate the certain application like deep dyeing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3691–3697, 2006     

Polyester nanocomposite fibers with improved flame retardancy and thermal stability

Polyester (PET) nanocomposite fibers were spun by adding master batches of linear low‐density polyethylene (LLDPE) loaded with Montmorillonite (MMT) nanoclay after compatibilizing the PET and LLDPE. The spun fibers showed increased thermal stability as well as flame retardancy, which increased progressively with the amount of nanoclay loaded into the fiber. There is slight decrease in tensile strength of the fiber accompanied by decrease in elongation % indicating addition of nanoclay makes the filaments stiffer. The onset of crystallization temperature occurred at higher temperature in case of composite fibers than on the neat PET fiber because of nucleating effect of nanoclay. The dyeability of the fibers was not affected and also had very little impact on the flame retardancy of the fiber. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Fine structure and physical properties of polyethylene/poly(ethylene terephthalate) bicomponent fibers in high‐speed spinning. I. Polyethylene sheath/poly(ethylene terephthalate) core fibers

The high‐speed melt spinning of sheath/core type bicomponent fibers was performed and the change of fiber structure with increasing take‐up velocity was investigated. Two kinds of polyethylene, high density and linear low density (HDPE, LLDPE) with melt flow rates (MFR) of 11 and 50, [HDPE(11), LLDPE(50)], and poly(ethylene terephthalate) (PET) were selected and two sets of sheath/core combinations [HDPE(11)/PET and LLDPE(50)/PET bicomponent fibers] were studied. The fiber structure formation and physical property effects on the take‐up velocities were investigated with birefringence, wide‐angle X‐ray diffraction, thermal analysis, tensile tests, and so forth. In the fiber structure formation of PE/PET, the PET component was developed but the PE components were suppressed in high‐speed spinning. The different kinds of PE had little affect on the fine structure formation of bicomponent fibers. The difference in the mechanical properties of the bicomponent fiber with the MFR was very small. The instability of the interface was shown above a take‐up velocity of 4 km/min, where the orientation‐induced crystallization of PET started. LLDPE(50)/PET has a larger difference in intrinsic viscosity and a higher stability of the interface compared to the HDPE(11)/PET bicomponent fibers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2254–2266, 2000     

SiO_2纳米粉体改性聚酯纤维的碱水解性能

研究了在PET合成过程中SiO2纳米粉体添加对其纤维碱水解性能的影响。结果表明,添加纳米粉体可促进PET纤维碱水解,并可在纤维表面形成长径比较小且分布均匀的微孔结构,为制备舒适性及易染性聚酯纤维创造了条件。纳米粉体质量分数为1.0%的改性PET纤维的碱减量率与处理时间呈非线性关系。     

Analysis of physical properties of PET/CD‐PET polyblend hollow fiber and its kinetics of alkaline hydrolysis

Cationic dyeable poly(ethylene terephthalate) (CD‐PET) was formed by copolymerizing dimethylterephthalate (DMT),5‐sodium sulfonate dimethyl isophthalate (SIPM) with a molar ratio of 2% and ethylene glycol (EG). Blends of regular poly(ethylene terephthalate) (PET) and CD‐PET were spun into hollow fibers. The fibers were then treated with aqueous NaOH. This study investigated the physical properties of PET/CD‐PET polyblend hollow fibers and their kinetic behavior of alkaline hydrolysis using differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), the density gradient method, a gel permeation chromatograph (GPC), a rheometer, and regression analysis of the statistical method. For the alkaline hydrolysis kinetics equation of PET, CD‐PET, and PET/CD‐PET polyblend materials: ? dW/dt = KC^αA^β, β values of chip and POY/ FOY hollow fibers are equal to 1. Moreover, R² of the kinetics equation of chip/POY/FOY for a from 1.09–1.35/1.08–1.32/1.06–1.29 were better than those of a = 1. Experimental results indicate that the rate constant of alkaline hydrolysis was CD‐PET hollow fiber > PET/CD‐PET polyblend hollow fibers > PET hollow fiber and FOY > POY > > Chip. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3601–3610, 2002     

PP/PET共混体系及其合金纤维的研究

用增容剂PP-g-AA增容PP/PET共混体系。研究了增容剂含量、共混物组成、共混时间、共混温度以及螺杆转速对PP/PET相形态的影响。结果表明:增容剂的加入大大改善了PP/PET两相间的相容性,并且增容剂的添加量有一最佳值,为PET质量的50%。随着PET含量的增加,分散相的尺寸有所增加。共混温度和共混时间均有一最佳值。随着螺杆转速的提高,分散相的尺寸减小,分布趋于均一,相容性也得到改善。另外,还制备了PP/PET合金纤维,对其表面处理后以及断面SEM观察均表明分散相PET原位成纤,这些微纤提高了合金纤维的力学性能。测试了合金纤维的力学性能,发现组分比为90/10/5时,合金纤维具有最好的力学性能。     

The decomposition kinetics of polyester microfiber fabrics by sodium glycerolate/glycerol solution

Polyester microfiber fabrics were alcoholyzed at 120, 140, and 160°C in 0.5, 1.0, and 1.5% (w/w) sodium glycerolate/glycerol solutions (NaGR) and the decomposition kinetics was studied in comparison to the hydrolysis done by a 5% aqueous sodium hydroxide solution (NaOH) at temperatures 80, 90, and 100°C. The activation energy and the Arrhenius pre-exponential factor of the alcoholysis found from this study were 30.57 kcal/mol and 2.04 × 10¹⁴/M s⁻¹, respectively. In comparison to the hydrolysis case, these values are much higher. The activation energy and the preexponential factor of the hydrolysis found from this study were 14.48 kcal/mol and 1.947 × 10⁶/M s⁻¹, respectively. The resulting surface morphologies observed by a scanning electron microscope showed that the NaGR-decomposed PET fiber surfaces were distinguished from the NaOH-decomposed PET fiber surfaces by a uniformly developed fine structure of microcraters. It is believed that such a fine microcrater structure of the NaGR-decomposed fiber surface is due to the greater pre-exponential factor as well as to the higher activation energy of the alcoholysis. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1217–1223, 1997     

Effect of fine structure on fatigue resistance property of poly(ethylene terephthalate) tire cord fibers

Seven experimental poly(ethylene terephthalate) (PET) fibers were spun and then drawn under different processing conditions (i.e., spinning speed and draw ratio) in such a way that the fibers possessed different long periods but retained the same crystal structure. Wide angle X‐ray diffraction, small angle X‐ray scattering, loss modulus, initial modulus, and taut tie molecules measurements were used to characterize the fine structure and the physical property of the fibers. The influence of the fine structure on the extensional fatigue behavior of the PET fibers was studied by subjecting them to 120–180 rpm at a repeated extension at 10⁴–10⁶ cycles. In order to detect the molecular motion of PET with the extensional fatigue, we carried out differential scanning calorimetry, X‐ray diffraction, density, and thermoluminescence (TL) experiments. The high temperature TL (above room temperature) intensity decreased with a 10⁴ cycle extension but increased with a 10⁵ cycle extension. The extent of change in the TL intensity was found to be a function of the long period and loss modulus. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 90–100, 2000     

聚酯纤维技术发展及前景探讨

从6个方面综述了近年来我国聚酯纤维的发展,并对发展前景进行了探讨。认为,锑系催化剂仍将会较长时间保留,特别是乙二醇锑应用前景广阔,但从环保出发,新型催化剂必须要研究开发。共缩聚改性应是聚酯改性的主流方法,而纳米无机粒子对面料和服装的表面处理以及微胶囊法制备功能纤维将会得到更大的发展。细旦化、超细旦化和异形化仍是聚酯纤维发展的重要趋势。聚酯纤维的发展取决于纺织加工中混纺技术的发展,后者将是未来聚酯面料制备的主要技术。实用的多组分复合技术将会有着良好的发展前景。重视聚酯的回收利用技术,也是聚酯纤维发展不可缺少的一环。     

Alkali resistance of a casein‐acrylonitrile graft copolymer fiber

The casein‐acrylonitrile graft copolymer fiber was treated in sodium hydroxide, sodium carbonate, and sodium bicarbonate solutions to evaluate its alkali resistance which was very important for wet processing. The weight loss and whiteness of the treated fibers were examined. UV spectra of the alkaline treatment solutions and IR spectra of the treated fibers were analyzed. The study showed that the fiber exhibited poor alkali resistance. Treating temperature, alkali concentration, and strength affected the weight loss and whiteness of the treated fibers. A high weight loss was found even at low alkali concentration, and the obvious yellowing was observed at higher alkali concentration and temperature. The weight loss was primarily due to the hydrolysis of casein, whereas the yellowing was caused by the hydrolysis of nitrile groups and induced formation of C?N conjugated system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008