Melt spinning and drawing process of PET side‐by‐side bicomponent fibers

The change of crimp contraction and shrinkage in the melt spinning and drawing process of polyethylene terephthalate (PET) side‐by‐side bicomponent fibers was studied. Regular PET and modified PET were selected to make a latent crimp yarn. The modified PET was synthesized to increase thermal shrinkage. The crimp contraction is mainly dependent on drawing conditions such as draw ratio, heat‐set temperature, and drawing temperature. Difference in shrinkage between the PET and the modified PET causes the self‐crimping of bicomponent fibers. Although changing the heat‐set temperature and the drawing temperature can not affect dimensional change, the crimp contraction varies with those variables. As the heat‐set temperature and the drawing temperature decrease, the crimp contraction increases. Difference in elongation also affects the crimp contraction in the effect of draw ratio. When the modified PET with neopentyl group was used for highly shrinkable part, the crimp contraction is greater in comparison with modified PET with dimethyl isophthalate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1362–1367, 2006     

Molecular structures and physical properties of heat‐drawn conjugate fibers

As‐spun poly(trimethylene terephthalate) (PTT)/poly(ethylene terephthalate) (PET) side‐by‐side conjugate fibers were drawn to investigate the effects of drawing conditions on structure development and physical properties. Effects of draw ratio and heat‐set temperature were observed. In the state of an as‐spun fiber, the molecular orientation of PTT was higher than PET, whereas PET molecular orientation increased remarkably over PTT with increasing draw ratio. Crimp contraction increased sharply at a draw ratio over 2.0, where the crystalline structure of the PET developed sufficiently. A heat‐set temperature of at least 140°C was required to develop sufficient crimp contraction. The crystallinity and orientation of the PET were attributed mainly to the crimp contraction of the drawn fiber. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Study of self‐crimp polyester fibers

Self‐crimp polyester yarns were manufactured using a conjugated spinning process involving two parallel but attached fibers with different shrinkage properties. A theoretical model proposed by Denton proved to be very useful for predicting crimp potential. Maintaining identical or very similar melt viscosities of the two components was demonstrated to be very critical for obtaining a straight interface and eliminating the dog‐legging problem. The crimp tests illustrate that the triangular shapes are superior to the round cross section. The optimum volume ratio for making a self‐crimp bicomponent skein is 50/50. Moreover, the optimal fiber thickness is 8 denier per filament. Finally, this study found that the combination of PET/PTT outperformed that of PET/PBT and PET/CD in terms of crimp potential, crimp stability, and elastic recovery. This phenomenon is primarily attributed to the markedly different thermal shrinkages of PET and PTT. POLYM. ENG. SCI. 45:838–845, 2005. © 2005 Society of Plastics Engineers     

拉伸工艺对PET/PTT复合纤维性能的影响

以310 dtex/48 f聚对苯二甲酸乙二醇酯(PET)/聚对苯二甲酸丙二醇酯(PTT)复合预向丝为原料,经拉伸后得到PET/PTT复合纤维,探讨了拉伸工艺对PET/PTT复合纤维力学性能和卷曲性能的影响。结果表明:在卷绕速度为500 m/min,拉伸温度160℃,热定型温度150℃的条件下,随着拉伸倍数的增加,PET/PTT复合纤维的断裂强度、沸水收缩率、卷曲收缩率明显提高,断裂伸长率呈下降趋势,卷曲稳定度变化不明显;拉伸温度和热定型温度对PET/PTT复合纤维力学性能和卷曲性能的影响相对较小;拉伸过程中,控制拉伸倍数为1.95～2.00,拉伸温度为140～160℃,热定型温度为130～170℃,PET/PTT复合纤维性能较好。     

Effect of zone drawing on the structure and properties of melt‐spun poly(trimethylene terephthalate) fiber

Melt‐spun poly(trimethylene terephthalate) (PTT) fibers were zone‐drawn and the structures and properties of the fibers were investigated in consideration of the spinning and zone‐drawing conditions. The draw ratio increased up to 4 with increasing drawing temperature to 180°C, at a maximum drawing stress of 220 MPa. Higher take‐up velocity gave lower drawability of the fiber. The PTT fiber taken up at 4000 rpm was hardly drawn, in spite of using maximum drawing stress, because a high degree of orientation had been achieved in the spinning procedure. However, an additional enhancement of birefringence was observed, indicating a further orientation of PTT molecules by zone drawing. The exotherm peak at 60°C disappeared and was shifted to a lower temperature with an increase in the take‐up velocity, which means that the orientation and crystallinity of the fiber increased. The d‐spacing of (002) plane increased with increasing take‐up velocity and draw ratio, whereas those of (010) and (001) planes decreased. In all cases, the crystal size increased with take‐up velocity and draw ratio. The cold‐drawn PTT fiber revealed a kink band structure, which disappeared as the drawing temperature was raised. The physical properties of zone‐drawn PTT fibers were improved as the draw ratio and take‐up velocity increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3471–3480, 2001     

纺丝温度对PET/PTT纤维结构与性能的影响

采用质量比为50/50的PET/PTT进行复合纺丝,纺丝速度2 300 m/min,经拉伸1.56倍,生产166dtex/72 f PET/PTT复合纤维,探讨了纺丝温度对PET/PTT复合纤维结构与性能的影响。结果表明:纺丝温度低时,PET/PTT纤维特性黏数高,纤维截面趋向于花生形;纺丝温度高时,纤维特性黏数低,纤维截面呈圆形;选择纺丝温度约275℃时,PET/PTT复合纤维具有良好的力学性能和卷曲性能,卷曲收缩率达39.6%。     

Melt spinning of β‐phase poly(vinylidene fluoride) yarns with and without a conductive core

When poly(vinylidene fluoride) (PVDF) is to be used as a piezoelectric material, the processing must include the formation of polar β‐phase crystallites, as well as the application of electrically conducting charge collectors, that is, electrodes. In this article, results from the melt spinning of PVDF yarns and a novel bicomponent PVDF‐yarn with a conductive carbon black/polypropylene (CB/PP) core are presented. Melt spinning has been done under conditions typical for industrial large‐scale fiber production. The effects on the resulting crystalline structure of varying the spinning velocity, draw rate, and draw temperature are discussed. The results show that, for maximum α‐to‐β phase transformation, cold drawing should take place at a temperature between 70 and 90°C, and both the draw ratio and the draw rate should be as high as possible. It was observed that the cold drawing necessary to form β‐phase crystallinity simultaneously leads to a decrease in the core conductivity of the bicomponent yarns. In this work, the melt spinning of bicomponent fibers with high‐β‐phase PVDF in the sheath and a CB/PP core was successfully accomplished. The core material remained electrically conductive, paving the way for the use of a CB‐polymer compound as inner electrode in the melt spinning of piezoelectric bicomponent fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

聚酰胺系并列型复合纤维卷曲性能的研究

对聚酰胺系(PA66—C_(710))并列型复合纤维的卷绕丝拉伸丝及沸水热处理后纤维,用密度法、声速法、X射线衍射法、DSC法、卷缩仪等测定了它们的超分子结构,力学性质和卷曲性能;研究了该复合纤维的成形、加工及热处理条件对其超分子结构形成的影响、超分子结构与其卷曲性能之间的关系;探讨了该复合纤维的卷曲机理。结果表明采用合适的纺丝油剂及合理的加工工艺及热处理条件,可以使聚酰胺系并列型复合纤维获得优良的接近于锦纶高弹丝的卷曲性能。     

Spinning and drawing properties of ultrahigh‐molecular‐weight polyethylene fibers prepared at varying concentrations and temperatures

The concentrations and temperatures of ultrahigh‐molecular‐weight polyethylene (UHMWPE) gel solutions exhibited a significant influence on their rheological and spinning properties. The shear viscosities of UHMWPE solutions increased consistently with increasing concentrations at a constant temperature above 80°C. Tremendously high shear viscosities of UHMWPE gel solutions were found as the temperatures reached 120–140°C, at which their shear viscosity values approached the maximum. The spinnable solutions are those gel solutions with optimum shear viscosities and relatively good homogeneity in nature. Moreover, the gel solution concentrations and spinning temperatures exhibited a significant influence on the drawability and microstructure of the as‐spun fibers. At each spinning temperature, the achievable draw ratios obtained for as‐spun fibers prepared near the optimum concentration are significantly higher than those of as‐spun fibers prepared at other concentrations. The critical draw ratio of the as‐spun fiber prepared at the optimum concentration approached a maximum value, as the spinning temperature reached the optimum value of 150°C. Further investigations indicated that the best orientation of the precursors of shish‐kebab‐like entities, birefringence, crystallinity, thermal and tensile properties were always accompanied with the as‐spun fiber prepared at the optimum concentration and temperature. Similar to those found for the as‐spun fibers, the birefringence and tensile properties of the draw fibers prepared at the optimum condition were always higher than those of drawn fibers prepared at other conditions but stretched to the same draw ratio. Possible mechanisms accounting for these interesting phenomena are proposed.     

热处理对COPET/PTT复合纤维卷曲性能的影响

以改性聚酯(COPET)及聚对苯二甲酸丙二醇酯(PTT)为原料经复合纺丝制备了COPET/PTT复合纤维,研究了热处理方式、温度和时间对COPET/PTT纤维卷曲性能的影响。结果表明:沸水处理优于干热处理;COPET/PTT复合比50/50的纤维具有较好的潜在卷曲性;湿热温度超过80℃,沸水处理时间10～20min,纤维卷曲性趋于稳定;干热温度在140～160℃时,纤维具有良好的卷曲性能;张力热处理有利于提高纤维的卷曲弹性回复能力。     

干湿热处理对PET/PTT纤维结构与性能的影响

通过对167dtex和111dtex聚对苯二甲酸乙二醇酯(PET)/聚对苯二甲酸丙二醇酯(PTT)双组分复合纤维的卷曲率、拉伸性能、声速取向及外观形态的测试,研究了干湿热处理对纤维结构与性能的影响。结果表明:经干、湿热处理后,纤维的断裂强度、声速值较处理前有显著下降,而卷曲率和断裂伸长率则明显著上升;湿热处理较干热处理对PET/PTT复合纤维断裂强度的影响较小。     

低中空高回弹三维螺旋卷曲纤维的制备及性能研究Ⅱ.拉伸工艺研究

将特性黏数差为0.064 dL/g的高、低黏度聚对苯二甲酸乙二醇酯(PET)制备的双组分并列复合中空纤维原丝进行拉伸制得拉伸丝(DT丝),对DT丝的拉伸工艺进行了研究,得到了低中空高回弹三维螺旋卷曲纤维的最佳拉伸工艺条件.结果表明:DT丝的三维卷曲性能和拉伸方式、拉伸倍率及其分配密切相关,采取二步拉伸、一级拉伸倍率较大...     

Formation and properties of polyester/copolyester conjugate fibers prepared by ultra‐high‐speed melt spinning technique

In this study, three types of conjugate fibers, sea‐islands type, orange split type, and side by side type, were prepared by using an on‐line steaming process through a high‐speed spinning technique in order to improve the processibility, efficiency, and properties of the fibers. It was found that the weight reduction ratios of orange split and sea‐island polyester/copolyester fibers were higher than that of polyester fibers. The SEM results indicate that the split time was shortened by using the ultra‐high‐speed melt spinning process. The nozzle‐draft increased and elongation decreased for side by side conjugate fibers after the spin speed was increased. The elasticity and crimp ratio of side by side conjugate fibers were significantly affected by the drawing temperature. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

海岛型双组分纤维的生产工艺和品质分析

将COPET与PET(或PA6)以(30～35)/(70～65)的比率在复合纺丝机上纺丝,可以制得物理机械性能优良和加工性能优良的海岛型双组分短纤维。从切片含水量、纺丝切片、纺丝复合比、纺丝温度、冷却成形条件、拉伸倍数和拉伸比率、拉伸温度和油浴油剂浓度、卷曲和松弛热定型过程的控制等方面,分析了海岛型双组分短纤维的生产工艺和品质。     

Preparation of poly(lactic acid) fiber by dry‐jet‐wet‐spinning. I. Influence of draw ratio on fiber properties

Poly(lactic acid) fiber was prepared by dry‐jet‐wet spinning of the polymer from chloroform solution and with methanol as the precipitating medium. The as‐spun fiber was subsequently made into high strength fiber by two‐step process of drawing at a temperature of 90°C and subsequent heat setting in the temperature range of 120°C. The draw ratio had significant influence on the crystallinity and the tensile strength of the fiber. The fiber with the tenacity of 0.6 GPa and modulus of 8.2 GPa was achieved at a draw ratio of 8. The differential scanning calorimetry revealed an increase in the glass‐transition temperature with the increase in the draw ratio, which suggests the orientation of chains during the drawing process. The surface morphology of the filament as revealed by scanning electron microscopy shows that fibers are porous in nature, but a significant reduction in the porosity and pore size of the fiber was observed with the increase in the draw ratio. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1239–1246, 2006     

PBT/PET conjugated fibers: Melt spinning,fiber properties,and thermal bonding

This work examines the PBT/PET sheath/core conjugated fiber, with reference to melt spinning, fiber properties and thermal bonding. Regarding the rheological behaviors in the conjugated spinning, PET and PBT show the smallest difference between their melt‐viscosity at temperatures of 290°C and 260°C respectively, which has been thought to represent optimal spinning conditions. The effect of processing parameters on the crystallinity of core material‐PET was observed and listed. In order of importance, these factors are the draw ratio, the heat‐set temperature, and the drawing temperature. The crystallinity of sheath material‐PBT, however, can be considered to be constant, independent of any processing parameters. The bulk orientation, rather than the crystallinity of PET core, dominates the tenacity of PBT/PET sheath/core fiber. Moreover, heat‐set treatment after drawing is recommended to yield a highly oriented conjugated fiber. With respect to thermal bonding, PBT/PET conjugated fibers processed via high draw ratio but low‐temperature heat setting can form optimal thermal bonds at a constant bonding temperature of 10°C above the T_m of PBT.     

聚丙烯并列型永久性三维卷曲中空纤维生产技术

介绍了用纽马格双组份复合短纤设备生产聚丙烯并列型三维卷曲中空纤维的生产技术。讨论了两种切片的熔融指数、纺丝温度、侧吹风、后拉伸倍数、卷曲、松弛定型工艺对产品质量及性能的影响。结果表明:两种切片的熔融指数差对中空度的影响较大,并影响纺丝的稳定性。后拉伸倍数影响纤维的卷曲数,松弛定型温度在125℃,时间15分钟能生产出质量稳定的聚丙烯永久性三维卷曲中空纤维。     

Influence of side‐chain structures on the viscoelasticity and elongation viscosity of polyethylene melts

Metallocene‐catalyzed, low‐density and linear low‐density polyethylenes with similar melt indexes were used to investigate how side‐chain structures influence the elongation viscosity and viscoelastic properties. The viscoelastic properties were determined with a rotation rheometer, while the elongation viscosities were acquired by using isothermal fiber spinning. The Phan‐Thien‐Tanner (PTT) model was also used to understand how the side‐chain structure affects the elongation behavior. Experimental results demonstrate that the log G′ vs. log G″ plot can qualitatively describe the effects of the side chain branch on the rheological properties of polyethylene melts. According to the results determined by the PTT model, low‐density polyethylene (LDPE) has low elongation viscosities at high strain rates. This low elongation viscosity can be attributed to the fact that LDPE has high shear thinning behavior. The long‐chain branching tends to increase entanglements, thereby enhancing the storage modulus, elongation viscosity and shear‐thinning behaviors. Uniform side‐chain distribution lowers the entanglements, which results in a low storage modulus, elongation viscosity and shear‐thinning behavior.     

双组份PE/PET同心皮芯型复合短纤维生产工艺

介绍了用纽马格双组份复合纺短纤生产线生产PE/PET的工艺,并对原料、纺丝温度、冷却条件、后拉伸倍数、卷曲、松弛定型等工艺条件进行了讨论.结果表明,选择合适的纺丝温度.冷却条件,后拉伸倍数在3.5左右,松弛定型温度105℃时,可生产出质量稳定的PE/PET同心皮芯型复合短纤维.     

Conducting bicomponent fibers obtained by melt spinning of PA6 and polyolefins containing high amounts of carbonaceous fillers

Melt spinning of conductive polymer composites (CPCs) is coupled with some difficulties such as a decrease of conductivity upon drawing and a reduced spinnability with increasing filler concentration. Applying bicomponent technology may provide the possibility to produce fibers from CPCs with a high filler concentration. A pilot‐scale bicomponent melt spinning set‐up was used to produce core/sheath fibers with fiber titers between 13 and 47 dtex. The sheath material was polyamide 6 (PA6) or polypropylene (PP) and the core material was a CPC. Two CPCs were used, polypropylene (PP) with carbon black (CB), denoted by PP/CB, and polyethylene (PE) with multiwalled carbon nanotubes (MWNT), denoted by PE/MWNT. The results showed that both materials could be used with a filler concentration of 10 wt % to obtain melt draw ratios up to 195. The volumetric fraction of core material in the bicomponent structure was 28%. A heat treatment of PP/CB fibers restored the conductivity to the level of the undrawn material, corresponding to an increase in conductivity by a factor 5. The same heat treatment had a positive effect on the conductivity of PE/MWNT fibers although the conductivity was not restored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011