Solvent‐induced modifications in polyester yarns. II. Structural and thermal behavior

The structural and thermal behaviors of polyester yarns treated with trichloroacetic acid–chloroform (TCAC) mixture were investigated by differential scanning calorimetric analysis (DSC), wide‐angle X‐ray scattering (WAXS), infrared spectroscopy (IR), and scanning electron microscopy (SEM). The effects of TCAC treatment on original fine filament (FFP) and microdenier (MDP) polyester yarns and on heat‐set polyester yarns were studied. It was found that the glass transition temperature of TCAC‐treated polyester yarns decreases with an increase in treatment concentration due to the plasticization effect, which is remarkable even at lower treatment concentration. The TCAC treatment on polyester yarns resulted in the formation of new crystallites in the extended noncrystalline domains of PET as well as growth and perfection of these new crystallites and the preexisting crystals. Further, the DSC thermograms revealed that TCAC treatment with 3% concentration could be able to overcome the structural changes in PET produced by heat setting at 180°C. The substantial changes in noncrystalline and crystalline domains observed were related to the mechanical properties of yarns. From the WAXS studies, an increase in crystal size and lateral order of TCAC‐treated polyester yarns was noted. The most distinct changes brought about by TCAC treatment include overall orientation determined by the trans–gauche ratio from IR measurements. The removal of oligomers and smoothening out of the fiber surface by TCAC treatment were observed from SEM studies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1555–1566, 2003     

An improved method for functionalisation of carbon nanotube spun yarns with aryldiazonium compounds

We report a method for modifying carbon nanotube (CNT) spun yarns with aryldiazonium salts that involves the pH controlled application of the diazonium salts to CNTs both during and after the yarn formation process. This largely facilitates the chemical accessibility to CNTs within the yarn, potentially enabling a more extensive and uniform modification. The modified CNT yarns were characterised by X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy, and also examined for their mechanical properties. The results demonstrated that a CNT spun yarn was effectively modified by this method without impairing the yarn integrity. The formation of oligomerised polyene structures on the CNT surfaces was observed. This modification resulted in an increase in tensile strength and Young’s modulus of the CNT yarn. The functional groups grafted on CNTs also provide opportunities to form crosslinks in the yarn to further improve mechanical properties.     

Structural and performance changes in polyester yarn brought about by simultaneous draw texturing processes

A partially oriented yarn of polyester has been subjected to the simultaneous draw texturing process and also drawn on the same machine without false twist. The effect of the variation of the applied draw ratio, the temperature of the first heater, the speed of the yarn, and (for textured yarn) the twist on the properties of the processed yarns was investigated. It was shown that the main factor affecting the properties is the applied draw ratio, the other factors having only a secondary influence, which is different from the findings with conventionally textured yarn. A tentative model for the polyesters based on fibrillar units with extended chains is proposed to account for the observed changes.     

医用防透视面料的研发与产业化

在防透涤纶长丝的研发基础上,优化防透单纤维的截面结构,优化防透涤纶长丝的复合结构和规格,制得了防透涤纶短纤维,与棉纤维等亲肤性好的其他纤维混纺制成纱线,用该纱线作为经纬纱织造,或用该纱线与防透涤纶长丝交织,制得兼顾防透视效果和服用舒适性、符合医护人员使用习惯的白色服装面料,解决了长期困扰"白衣天使"夏季衣着暴露的问题。     

Modal/涤纶混纺纱上浆工艺研究

根据Modal/涤纶混纺纱性能,制定出4种浆料配方,并对浆液及浆膜性能进行了测试分析。分别采用这4种配方的浆料对Modal/涤纶混纺纱进行浆纱试验,测试了不同配方浆纱的各项性能,从而得出适合Modal/涤纶混纺纱的浆料配方。     

Improvement in the bonding strength of laminated composites by using air‐textured core‐and‐effect glass yarns

Delamination is the most common failure mode in laminated composites due to the reduced strength in the through‐the‐thickness direction. Air‐jet texturing was used to produce bulk and loops in the yarn, which provides more surface contact between the fibers and the resin. The development of core‐and‐effect textured glass yarns and the effect of texturing parameters were presented in the previous article. This article describes the effect of texturing on the mechanical properties including tensile properties, flexure properties, interlaminar shear strength (ILSS) and fracture toughness (Mode I) of glass laminated composites. The composites of plain and twill weave fabrics were developed from both the textured and nontextured yarns. It was observed that the tensile properties decreased and the flexure properties remained unchanged after texturing. However, significant improvement was observed in ILSS and the Mode I fracture toughness of the composites after texturing. The bulkier, loopy structure of the textured yarn provided more surface contact between the fiber and the resin and significantly improved the bonding strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effect of process variables on bulk development of air‐textured poly(trimethylene terephthalate) bulk continuous filaments

Bulk development of air‐textured poly(trimethylene terephthalate) (PTT) bulk continuous filaments was studied by varying two texturing parameters, yarn preheating and texturing hot air temperatures. The yarns were subsequently heat treated from 80 to 160°C. Bulk was found to go through a maximum with increasing heat‐treatment temperature because of two competing mechanisms. Upon heat treatment, the fiber shrunk and developed bulk; heat treatment also simultaneously induced structural reorganization through annealing and stabilized the fiber against shrinkage. When the later mechanism became dominant, bulk development decreased with further increase of heat‐treatment temperature. The temperature at which the maximum occurred increased when the yarn preheating or texturing air temperatures were increased. Depending on the extent of annealing and structural reorganization during yarn preheating and during texturing, fibers with equivalent bulk measured at a single temperature did not behave the same way over a range of heat‐treatment temperatures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1011–1017, 2004     

Effect of short polyethylene terephthalate fibers on properties of ethylene-propylene diene rubber composites

The alteration in some properties of electron beam (EB) cured ethylene-propylene diene rubber (EPDM) reinforced by polyethylene terephthalate (PET) fiber was investigated in this study. Bonding system Resorcinol/Hexamethylenetetramine/Silica (RHS) was used to enhance the fiber/EPDM adhesion and to maintain optimum composite strength properties. Mechanical properties of composites namely; tensile strength, hardness and modulus at 100 % elongation have been enhanced by adding PET fibers and increasing irradiation dose. Moreover, the effect of fiber loading and irradiation dose on the soluble fraction behavior of the composite in benzene was also investigated. The soluble fraction of the composites decreased with increasing the fiber loading and irradiation dose. The extent of fiber alignment and strength of fiber-rubber interface adhesion were analyzed from the anisotropic swelling measurements. In addition, thermal stability of the composites was increased. Besides, the mechanical properties like tensile strength and stiffness were improved by thermal ageing. Scanning electron microscopy (SEM) for the fractured surfaces and Wide- angle X- ray diffraction (WAXD) of the investigated samples confirmed that the adhesion occurred between fibers and EPDM.     

Generation of a fibrillar core in PET fiber by cold drawing

Cold draw processing of poly(ethylene terephthalate) yarns has been discovered that yields a sheath/fibrillar core (s/fc) microstructure in the each fiber of a yarn. When aged, unoriented, noncrystalline spun yarns were cold drawn, high (>5.7 : 1) draw ratios could be achieved and an s/fc microstructure resulted. Cold drawing also generated a high oriented amorphous content. The tensile and shrinkage properties of yarns with the s/fc microstructure and high oriented amorphous content were examined as function of processing (drawing, annealing, and relaxing). The microstructure was examined by scanning electron microscopy, transmission electron microscopy, small‐angle X‐ray scattering, wide‐angle X‐ray scattering, and optical microscopy. The fibrillar microstructure survives all processing. Management of the oriented amorphous component under heat and tension contributes to the greater stiffness (modulus) and dimensional stability of processed s/fc yarns. The properties of yarns with an s/fc microstructure are compared with more conventional hot drawn yarns. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2335–2352, 1999     

捆绑纱对预定向经编织物性能的影响

通过用玻璃纤维／涤纶捆绑纱及不同经编组织结构,研究捆绑纱对预定向经编织物性能的影响。结果表明,玻纤可用于捆绑纱组织中,其编织后强度比涤纶纱高33．3％。玻纤捆绑纱可改善树脂对织物的浸渍性,降低最终复合材料的孔隙率,提高复合材料的拉伸和剪切等力学性能。不同的捆绑纱组织结构对复合材料的力学性能影响显著,玻纤做捆绑纱时,经平组织比编链组织复合材料的经向拉伸强度高7．97％,弯曲强度高约5％。     

细旦多孔异彩复合假捻变形丝的生产工艺

采用阳离子染料可染改性聚酯切片,经熔融纺丝制得细旦多孔阳离子染料可染涤纶预取向丝(POY),在假捻变形加弹机上与细旦多孔常规涤纶POY以特别方式复合混纤加工,可制得一染异色的细旦多孔异彩复合假捻变形丝,产品适用于高档起绒面料,并具有重要的环保意义。     

单向聚酯帘线/橡胶复合材料的疲劳损伤机理

利用较Ｘ射线技术和扫描电子显微镜技术,研究了在周期载荷下单向聚酯帘线／橡胶复合材料的疲劳机理。结果表明,在高应务下,单向聚酯帘线／橡胶复合材料的疲劳损伤以聚酯帘线断裂为主,在中应力下,单向聚酯帘线／橡胶复合材料的疲劳损伤是逐步进行的;在你力下,单向聚酯帘线／橡胶复合材料的疲劳损伤仅有局部的界面损伤。     

Investigation on the motion of different types of fibers in the vortex spinning nozzle

A numerical model is presented to simulate the fiber motion in the airflow inside the vortex spinning nozzle (VSN). The coupling between the fiber and airflow together with the fiber‐wall contact is solved. Based on the numerical model, the motional characteristics of four types of fibers—cotton, viscose rayon, lyocell, and polyester fibers—in the airflow inside the vortex spinning nozzle are simulated and analyzed. The vortex yarn structure is viewed under the scanning electron microscope and the fiber strength utilization factors of the vortex yarns spun from different types of fibers are compared to verify the wrapping effects of different types of fibers in the vortex yarns obtained by the numerical simulation. The agreement between the numerical and experimental results shows that the numerical modeling methodology proposed in this research provides a reliable way of investigating the fiber dynamics in airflow and an efficient solution to the mechanical problems in polymer/textile manufacturing processes involving fluid–solid coupling. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

聚酯粗细丝的生产技术

简单介绍了聚酯粗细丝的各种生产技术。粗细丝可以通过在熔纺中加入添加剂，异形喷丝权法、拉伸法、变形法或某两种方法结合起来制取。此外还简要介绍了粗细丝在后加工时应注意的一些问题。     

民机铝合金蒙皮的激光织构化处理

采用波长为1064 nm的激光表面处理设备在2024-T3铝合金表面刻蚀出平行线、正方形和菱形这3种织构表面。采用扫描电子显微镜与激光共聚焦显微镜观察了不同织构表面的微观形貌。通过测量对水和甘油的接触角来评价它们的浸润性。用拉脱法测试了其表面环氧涂层的附着力。结果表明,在单位面积能量密度相同的情况下,表面织构为正方形和菱形的试样表面粗糙度由处理前的1.9μm分别提升至7.6μm和7.9μm,表现出更好的浸润性,环氧涂层的附着力比未处理试样提高了70%左右,而平行线织构表面的涂层附着力只提高了24%。通过金相观察、强度失效分析及硬度测试发现,织构化处理对飞机蒙皮的力学性能基本没有影响。     

Molecular design of multicomponent polymer systems. XVIII: Emulsification of high-impact polystyrene and low density polyethylene blends into high-impact alloys

The interfacial activity of a hydrogenated polybutadiene-polystyrene tapered diblock copolymer, (HPB-b-PS) is investigated in blends of a low density polyethylene (LDPE) with a high impact polystyrene (HIPS) prepared in the melt state on a two-roll mill. Optical and scanning electron microscopy examinations of smoothed or fracture surfaces and also surfaces obtained after THF-extraction of PS phases demonstrate that the copolymer promotes the dispersion and interfacial adhesion of the components, whatever the composition and is able to create and stabilize particular dispersions of the rubber particles in these blends. Tensile and Charpy impact properties are also very significantly improved. All these features demonstrate that the ductility and toughness of PS and LDPE/PS blends can be closely controlled by adequate combinations of rubber particles and a HPB-b-PS copolymer.     

Mechanical properties and morphology of hot drawn polyacrylonitrile nanofibrous yarn

In this study PAN nanofibrous yarn was produced by two‐nozzle conjugated electrospinning method. The nanofibrous yarns were drawn continuously in boiling water with drawing ratios of 1, 2, 3, and 4. The morphology of drawn yarns was investigated by scanning electron microscopy and tested for tensile properties as well as untreated yarn. The results showed that the nanofiber alignment in the yarn axis direction, the tensile strength, and tensile modulus of yarn increases as a result of drawing while the tensile strain and work of rapture decrease. X‐ray diffraction patterns of the produced yarns were analyzed as well. It was found that crystallinity index increases as the draw ratio increases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of silane monomer on the improvement of mechanical and degradable properties of photografted jute yarn with acrylamide

UV radiation was used to graft acrylamide (AA) to jute yarn in order to improve the mechanical properties. The physicomechanical properties of the grafted jute yarn were investigated. A series of solutions of different AA concentrations in methanol along with photoinitiator (Irgacure‐907, 2%) were prepared. The jute yarns were soaked in the solution for 30 min before radiation. The effect of irradiation time, concentration of monomer on polymer loading, and tensile properties of the jute yarn were studied. The highest polymer loading (22%) and tensile strength (95%) of the yarn were observed when the yarn was treated in 30% AA in methanol with 60 min of UV radiation. The surfaces of both treated and untreated jute were characterized by X‐ray photospectrometry, infrared spectroscopy, and environmental scanning electron microscopy, and it was observed that the AA reacted or deposited on the jute surface. A minute amount (1%) of silane monomer [3‐(trimethoxysilyl)‐propyl methacrylate] was used as an additive in the AA solution to further improve the mechanical properties of jute yarn. Better improvement was achieved by using 1% silane monomer. Water uptake, simulating weathering, and soil degradation tests of untreated and treated yarns were also performed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3530–3538, 2003     

保暖发热聚酯纤维的开发

将电气石母粒添加到聚酯中,纺制成中空形聚酯预取向丝,再经假捻变形加工使其具有三维卷曲形态,开发出保暖发热聚酯纤维。假捻变形时第一热箱温度控制在180~190℃,纤维断裂强度为3.2 c N/dtex,卷曲收缩率为24%。经测试表明:该纤维的远红外法向发射率为88%,温升为2.9℃,中空形状保持完好。     

细旦多孔异彩复合假捻变形丝的生产工艺

采用阳离子染料可染改性聚酯切片,经熔融纺丝制得细旦多孔阳离子染料可染涤纶预取向丝(POY),在假捻变形加弹机上与细旦多孔常规涤纶POY以特别方式复合混纤加工,可制得一染异色的细旦多孔异彩复合假捻变形丝,产品适用于高档起绒面料,并具有重要的环保意义。