高速纺涤纶中空长丝的研制

通过对特殊喷丝板的设计和纺丝工艺的探讨 ,研究了影响高速纺涤纶中空长丝成形的主要因素 ,讨论了喷丝板的设计原则。结果表明 :纺丝速度为 2 .8～ 3.2 km/m in,纺制 POY中空纤维 ,卷绕正常 ,可满足后加工的要求 ;纺丝速度增加 ,中空度降低 ,熔体温度控制在 30 0～ 30 2℃ ;中空喷丝板设计时 ,微孔圆环形狭缝宽度小于 0 .15 mm ,表观拉伸比不能太大 ;POY中空度一般为 15 %～ 2 8% ,F DY的中空度可达 5 0 %。     

高速纺锦纶6帘子线油剂开发

探讨了高速纺锦纶6帘子线各生产工序对油剂的要求及单体选择,自主开发了N614A油剂,其组成及各组分的质量分数分别为:合成酯10％～30％,聚醚65％～85％,添加剂5％～10％。该油剂在13kt/a纺丝装置上进行工业试验,结果表明:油剂的耐热性、可纺性优异;帘子线原丝的定负荷伸长率为11.6％,断裂伸长率23.3％,帘子布的H抽出为216.6N(1 870 dtex/2 f),完全满足质量要求。     

Determination of acid impurity content in spinning solution and in freshly spun fibre made from aromatic polyamides

Conclusions The spinning solution from the manufacture of fibre from an aromatic polyamide contains dissolved HCl in the free form and HCl bonded to functional groups of the polymer; the freshly spun fibre contains only bonded HCl.A procedure has been developed for determining the content of free and bound HCl in spinning solution and freshly spun fibre; it is based on titrating a sample of a specimen in a medium of dimethylacetamide containing 3% LiCl with an approximately 0.04-molar alcoholic KOH solution.Translated from Khimicheskie Volokna, No. 2, pp. 58–60, March–April, 1990.     

油剂对高速纺锦纶6帘子线质量的影响

探讨了油剂对锦纶 6帘子线质量的影响 ,确定了平滑剂为相对分子质量 5 0 0 0的聚醚及脂肪酸双酯。聚醚分子中环氧乙烷与环氧丙烷的比例为 0 .7～ 1.6,油剂中加入烷基磷酸盐可降低原丝捻织后的强力损失 ,加入酯类化合物可有效提高帘子布的粘着强力。油剂中聚醚与合成酯含量比例为 3～ 4,合成酯含量约为 2 0 %时 ,油剂的整体使用性能最佳。     

Structure and property studies of poly(trimethylene terephthalate) high-speed melt spun fibers

Poly(trimethylene terephthalate) has been melt spun at various take-up velocities from 0.5 to 8 km/min to prepare fiber samples. The effect of take-up velocity on the structure and properties of as-spun fibers has been characterized through measurements of birefringence, density, wide-angle X-ray scattering, DSC melting behavior, tensile properties and boiling water shrinkage (BWS). The birefringence exhibits a maximum at take-up velocities between 3 and 4 km/min. The fiber samples spun at the lower take-up speeds have essentially amorphous structures, while the filaments prepared at a velocity range higher than 4 km/min all possess an obvious crystalline structure. With increasing take-up speed, a steady improvement in tensile strength, elongation to break, and BWS is found, whereas the initial modulus remains almost constant within the measurement error, over the entire take-up speed range between 0.5 and 8 km/min.     

Dyeing behaviour of poly(ethylene terephthalate) fibres spun by high-speed melt spinning

Poly(ethylene terephthalate) (polyester) fibres were spun using a high-speed melt spinning method. By changing the spinning conditions, polyester fibres with differences in crystallinity, birefringence and melting point were obtained. The dyeing behaviour of these fibres was investigated using CI Disperse Red 1. The degree of crystallisation of polyester lowered the dyeability. The fibres with lower molecular orientation and larger crystallite size showed better dyeability.     

Surface area of aqueous sodium hydroxide hydrolyzed high-speed spun poly(ethylene terephthalate) fibers

The specific surface area (SSA) of delustered undrawn and drawn high-speed spun PET fibers hydrolyzed in aqueous NaOH was measured using three methods: (1) geometric, based on fiber diameter; (2) gas adsorption using N₂ and the BET equation; and (3) adsorption of a nonionic surfactant. Increasing the spinning speed had little effect on the SSA of the untreated fibers, while drawing resulted in considerably larger SSA. For the hydrolyzed fibers, both adsorption methods resulted in larger SSAs than that predicted geometrically due to surface pitting. After hydrolysis, the higher spinning speed resulted in a greater increase in SSA over the untreated sample, whereas the increase in SSA was less for the drawn fibers compared to the undrawn. The kinetics of hydrolysis are also discussed. © 1995 John Wiley & Sons, Inc.     

锦纶6帘子线高速纺卷绕成形影响因素浅析

从工艺和设备上探讨了影响锦纶6帘子线高速纺卷绕成形的主要影响因素。结果表明:对于2100dtex产品,卷绕角为9.0°-9.5°,卷绕张力控制在0.098 cN／dtex,K值(摩擦辊速度／第四对热牵伸辊速度)选择为93％,卷绕机接触压力为300 kPa,上油率控制在1.2％-1.3％,有利于卷绕成形。对卷绕机卡盘与摩擦辊的平行度、导丝装置等进行定期检查校准,可保证卷绕成形良好。     

On the overdrawing of melt‐spun isotactic polypropylene tapes

The morphology and mechanical properties of melt‐spun and post‐drawn isotactic polypropylene (iPP) tapes have been studied in order to examine their dependence on the post‐draw ratio applied. Special attention is focused on the characterization of the so‐called overdrawing behavior of the tapes; at a certain draw ratio, a change of the optical appearance of the tape from transparent to opaque is observed. Overdrawing is accompanied with changes in the mechanical properties, surface, and morphology of the tapes. For post‐draw ratios without overdrawing, and for highly overdrawn tapes, the variation in the mechanical properties measured is very small, but for slightly overdrawn tapes, a large scattering of mechanical properties has been measured. In the latter case, this behavior is related to the start of internal delamination of the tapes during post drawing. It is shown that strongly overdrawn tapes have excellent mechanical properties, in particular, high specific stiffness and strength. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2920–2931, 2007     

Phase transition in polyamides

Summary A series of poly(3,3′, 5,5′-tetraethyldiphenylmethane-1,m-alkanedi-carboxamide(poly(TEDPM-ADA(m=8–18)))) were synthesized from 1,m-alkane-dicarboxylic acids(ADA(m=8–18)) and 4,4′-diamino-3,3′,5,5′-tetraethyl-diphenylmethane by use of direct polycondensation in the presence of triphenylphosphite. The enantiotropic nematic liquid crystals were observed in the m=12–18 and monotropic liquid crystals were observed in the m=8–11 in poly(TEDPM-ADA). Mesogenicity of the polyamides increases with an increase in the number of methylene spacers, m.     

Inverse relaxation in spun yarns

This paper presents some experimental data on inverse relaxation exhibited by yarns spun from cotton, polyester, viscose rayon, and jute fibers. Inverse relaxation (IR) is the building up of tension in a viscoelastic material that has been allowed to recover a part of the initial extension it is subjected to. The IR index defined as a measure of the extent of this property has been determined at various levels of extension. A qualitative explanation of the results based on the fiber model proposed by Vitkauskas and Matukonis is also given.     

Structure-property relationships in amorphous polyamides

New methods are put forward to explain the numerical values of some useful bulk physical properties of amorphous copolyamides, in terms of parameters related to monomer structure. Polyamides based on adipic, tetramethylsuberic, iso- and tere-phthalic acids, and diamines including isophorone, xylylene, cyclohexane, hexamethylene and its trimethyl derivatives, methylnonane and dodecamethylene diamines were studied. ε-Caprolactam and 12-aminododecanoic acid were also used as comonomers. In Part I, an empirical rule is proposed, based on experimental observations which predicts whether a copolyamide has an amorphous or crystalline character. The rule is based on the individual stereochemical contributions of the constituent monomers to the overall polymer chain structure. A relationship between Vicat softening point and monomer composition is derived from experimental data, which seems to be generally applicable to all amorphous polyamides of the diacid/diamine type. Each monomer makes a molar contribution which has been determined experimentally for all the materials studied. An arbitrary set of simple structural rules has been devised which enables the molar contributions of monomers to be related to their chemical structure. This procedure provided a method of predicting the contributions of other monomers for which molar constants had not been measured, and was successfully tested for a limited number of materials. A modified relationship was obtained experimentally to explain the effect of amino-acids on Vicat softening point.In Part II, the relationships outlined in Part I are combined on the basis of experimental evidence to provide an empirical relationship between composition and impact strength. This relationship predicted the impact strengths of the majority of eighty copolyamides, of widely different chemical structure, with a reasonably good accuracy. Substantial inaccuracy occurred only when a large proportion of a long chain aliphatic monomer was present in the polyamide. Tentative correlations between tensile strength and carbon chain length were observed from a limited number of measurements which suggests that tensile strength may be a constitutive property. The main conclusions of this work are: (a) polyamides are naturally crystalline with high melting points if more than 80% of the monomer units are symmetrical; (b) Vicat softening point and tensile strength decrease linearly with increasing monomer chain length; the softening point is particularly affected by the presence of substituent groups; (c) amino-acids reduce symmetry, impact strength and Vicat softening points of copolyamides; (d) Charpy impact strength increases with the proportion of symmetric monomer units, the rigidity of the acid and flexibility of the diamine structures; (e) tensile strength and flexural modulus correlate with each other in copolyamides of diacids and diamines and both increase as the amount and chain length of aliphatic monomer is reduced; (f) by using the empirical relationships developed in this work, it has proved possible to formulate amorphous polyamides with outstanding combinations of physical properties, when compared with commercially available polymers.     

Glass transition in aliphatic polyamides

The glass transition temperature is analyzed in polyamide systems characterized, owing to their chemical composition, by the absence of hydrogen bonds. The physical behavior exhibited by these systems is similar to that observed in conventional aliphatic polyamides, suggesting that, besides the hydrogen bonds, the amidic group itself plays a specific and important role in determining the polymer physical behavior generally and, in particular, the glass transition mechanism. It is surmised that this role is connected with the polar and rigid character of the amidic group, affecting chain-chain interactions and chain mobility.     

储罐底板焊接变形的控制方法

石化行业有很多储罐底板是由很多钢板拼接制作而成,比较关键的部位之一是底板,底板焊接最不易控制的是底板焊接变形。其中,波浪变形是最常见的底板变形。很多施工单位常见焊接接头的质量非常好,但唯一的缺点是底板变形控制不住,既产生返工,又影响焊接接头的质量,而且越返工,变形就越大。通过以下三例不同储罐的施工总结,反映一些施工中的普遍规律。     

半芳香尼龙合成工艺研究进展

简介了半芳香尼龙的优良性能,着重叙述了半芳香尼龙合成工艺在高温高压溶液缩聚法、低温溶液缩聚法、聚酯缩聚法和直接熔融缩聚法4个方面的研究进展,并分析了各合成工艺方法的优缺点;同时指出,大有效反应体积、具有自清洁性的高效高粘流体混合与脱挥装置将会成为半芳香尼龙合成工艺的重点研究发展方向。     

New solvent for polyamides and its application to the electrospinning of polyamides 11 and 12

Polyamides with long hydrocarbon chains, e.g. PA11 and PA12, are generally dissolved in phenolic or fluoric solvents that prevent these polymers from being electrospun and used in many applications because of their high boiling point and/or prohibitive cost. We demonstrate that a mixture of formic acid and dichloromethane can lead to the dissolution of various polyamides enabling their subsequent electrospinning. Nanofibers and nanoribbons of 130 nm and greater in average diameter were obtained and characterized using scanning electron microscopy and Raman spectroscopy.     

Structural memory in chromium coordinated polyamides

It was established by X-ray diffractometry that swelling agents caused a γ → α transition in chromium coordinated polyamides. This structural memory effect can well be interpreted by the formation of the mixed complex, [Cr(CO_amide)_n(H₂O)_6?n]³⁺ proposed previously. The structure controlling the increase in the melt viscosity corresponds to n ? 2 while a treatment with a swelling agent (e.g. water) results in a complex structure of $\text{n ? 1}$ by ligand exchange. The latter involves a destruction of the partly crosslinked structure conferring the possibility of the structural memory.