溶液喷射纺丝制备PMIA/MWNTs纳米纤维的研究（英文）

采用溶液喷射纺丝技术制备间位芳纶/多壁碳纳米管(PMIA/MWNTs)纳米纤维,探讨了不同工艺参数下纳米纤维表观形貌和直径分布的变化,研究了MWNTs对PMIA纳米纤维膜结晶性能和力学性能的影响。结果表明:在拉伸风压为0.12 MPa、喷丝孔内径为0.4~0.5 mm时,可以制得形貌较好的PMIA/MWNTs纳米纤维;随MWNTs负载量的增加,制得纳米纤维的平均直径变粗,结晶度变大,纤维膜拉伸强度增大,断裂伸长率则下降;MWNTs的最佳负载量为0.3%,此时可制得形貌结构均匀,直径较细的PMIA/MWNTs纳米纤维,纤维平均直径为372 nm,纤维膜拉伸强度达到41.85 MPa,较纯PMIA纳米纤维膜提高了86%以上。     

溶胶共混纺丝制备水性中间相沥青基碳纤维

以针状焦(GNC)为原料,采用混酸一步氧化法制备水性中间相沥青(AMP)、混酸两步氧化法制备改进水性中间相沥青(FHAMP),分别与聚丙烯腈(PAN)共混溶解于二甲基亚砜(DMSO)形成溶胶,然后以稀硫酸为凝固剂,经溶胶纺丝、直接炭化制得水性中间相沥青基碳纤维;研究了AMP和FHAMP的溶解性、流变性、可纺性,以及相应的碳纤维的结构与性能。结果表明:相比AMP,FHAMP的粒径显著减小,氧化程度更高,能更好地溶解于DMSO;引入PAN,可有效提高AMP和FHAMP溶胶的可纺性;在纺丝温度50℃时,PAN质量分数为10%的AMP溶胶及PAN质量分数为8%的FHAMP溶胶均有较好的可纺性,连续收丝长度超过1 000 m,FHAMP溶胶的纺丝稳定性更好;相比由AMP得到的碳纤维,由FHAMP得到的碳纤维截面结构较为致密,纤维直径减小至23.09μm,杨氏模量和拉伸强度分别提高至33 GPa和0.29 GPa。     

纺粘法制备PA 6粘合纤维的工艺研究

利用纺粘非织造设备制备锦纶6(PA 6)粘合纤维,研究了泵供量、拉伸气流强度和纺丝温度对PA6粘合纤维结构和力学性能的影响。结果表明:纤维结晶度随着拉伸气流强度的增加而增加;纤维直径随着泵供量减小和拉伸气流强度增加而减小;纤维的断裂强度随着拉伸气流强度的增加而增加,纤维的断裂伸长率随之逐渐减小;泵供量和纺丝温度对纤维的结构和力学性能影响较小;当纺丝温度为240℃,泵供量为96m L/min,拉伸风电机频率为40 Hz时,所制得的PA 6纤维直径为26.7μm,断裂强度为2.36 c N/dtex,断裂伸长率为1 760.2%。     

Preparation of crimped synthetic fibres directly in the spinning process

Conclusions In the preparation of crimped polyamide yarns without the use of texturing devices, it has been found that in yarns of complex profile, of the head-tail type, the two parts of the yarn cross-section interact in accordance with the bimetallic plate rule. The crimp can be described satisfactorily by the Brand-Backer equation.Dependences of the degree of crimp on the ratio of the head and tail lengths, birefringence, and spinning speed have been obtained for selected variants of yarn profile; this makes it possible to find an optimum regime for yarn preparation.Translated from Khimicheskie Volokna, No. 3, pp. 32–33, May–June, 1985.     

Dynamics and kinematics of the process of spinning man-made fibres by the wet method

Conclusions The change in yarn tension has been calculated theoretically as a function of the precipitant concentration in the precipitation bath. For the investigated system (polyoxadiazole), the calculated range in change of tension on transition from mild to severe spinning conditions is 0.45×10^–4<F<0.58×10^–3 N (under conditions of constant rate of take-up).It has been shown that under severe spinning regimes the assigned rate of take-up is attained immediately on exit from the spinneret channel.The effect of yarn tension on expansion (compression) of the polymer jet after exit from the channel has been qualitatively investigated. For polyoxadiazole, the coefficient of jet expansion (compression) varies within the range 0.53<B*<1.77, depending on F.Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1989.     

Influence of spinning parameters on synthesis of alumina fibres by centrifugal spinning

The present study investigates the synthesis of alumina fibres of 5–15?µm dia. by sol-gel process through centrifugal spinning. Among various spinning parameters such as rpm, viscosity, humidity, chamber temperature etc., effect of rpm and viscosity on quality of spun fibres was examined in order to spin less defective (less shots) fibres. From the rpm vs viscosity experiments, it was concluded that viscosity between 13 and 42?Pa.s with 3000?rpm was favourable for obtaining fibres containing less shots. It was shown that besides viscosity, refractive index and percent weight loss of the aged sol can be used as indicator for determining spinnability of alumina precursor sols. Influence of only preheating and continuous heating of the chamber during spinning were also investigated and it was found that only preheating did not help in producing fibres. Besides this, influence of hot air blower (HAB) aligned in different directions with respect to the spinnerette, on fibre quality was tested. It was observed that the quality of fibres did not change due to change in HAB direction.     

Poly(vinyl pyrrolidone) sub-microfibers produced by solution blow spinning

In this study, poly(vinyl pyrrolidone) (PVP) polymeric fibers were obtained by the solution blow-spinning (SBS) technique using PVP of low molecular weight. The fabrication of nano-microfibers of polymers with low molecular weights by using the SBS or electrospinning (ES) techniques is not common. Most theoretical studies suggest that only high-molecular-weight polymers can be produced because of their rheological properties. The influence of solution parameters (concentration, solvent volatility, and viscosity) and processing parameters (injection rate, collector rotation, gas pressure, and needle size protuberance) on the formation, morphology, and physical properties of the PVP fibers was investigated using the images obtained by scanning electron microscopy (SEM), thermal analysis (DSC/TG), x-ray diffraction (XRD) patterns, and Fourier-transform infrared spectroscopy (FTIR) spectra. The results showed no significate changes in the polymer properties because of fiber processing. Additionally, the fiber diameter frequency distribution was analyzed for each condition studied, and the behaviors of the fiber diameters with higher occurrences were evaluated as a function of the variables in the study, revealing that there is no simple relationship between the fiber diameter and processing conditions.     

Change in the acoustical characteristics of man-made fibres during the spinning process

Conclusions The relaxation character of the change in sound propagation velocity in man-made fibres during the stretching process has been confirmed.A relationship has been proposed which describes the change in sound velocity as a result of two competing processes: disorientation and orientation at low and large degrees of stretch, respectively.Translated from Khimicheskie Volokna, No. 4, pp. 18–19, July–August, 1985.     

Effective polyethyleneterephthalate particles on the spinning process and properties of polyester fibres

Conclusions The polyethyleneterephthalate dust particles which are formed as a result of abrasion of the flake during transportation are highly crystalline, low- and medium-molecular fractions of the polymer which contain an elevated amount of ash-type impurities.An increase in the content of polyethylene terephthalate dust particles in the flake above 0.1% by wt. impairs the homogeneity of the polymer melt, reduces the stability of the spinning process, and reduces the uniformity in physicomechanical characteristics of the polymer yarns.Translated from Khimicheskie Volokna, No. 2, pp. 14–16, March–April, 1990.     

Tube spinning of viscose fibres

Conclusions Tube spinning of viscose fibres makes it possible to reduce the hydrodynamic frictional resistance of the precipitation bath.The possibility is created of raising spinning speed, increasing the number of spinneret holes, and raising fibre quality.On use of tube spinning, questions of reducing gas contamination of the working zone and mechanizing spinneret replacement are solved more effectively.Translated from Khimicheskie Volokna, No. 2, pp. 8–13, March–April, 1986.     

Wet spinning of asymmetric hollow polysulfone fibres by the double spinning bath method

The possibility of fabricating an asymmetric hollow fibre from polysulfone in a one-stage process with the double spinning bath method was demonstrated. A correlation was established between the quality of the selective layer and the value of the diffusion coefficient of the solvent in the precipitant.Russian Institute of Chemical Technology, Moscow. Translated from Khimicheskie Volokna, No. 6, pp. 24–26, November–December, 1993.     

Orientational strengthening of polyester fibres fabricated by high-speed spinning

An analysis was performed and the effective (orientational) stretching for high-speed spinning (HSS) and drawing of POY was estimated. The major possibility of strengthening POY to 60 cN/tex and higher by two-stage drawing, cold in the first stage, and with heating near the temperature of the maximum rate of crystallization in the second, was demonstrated. A hypothesis was advanced concerning the possibility and expediency of introducing this process in industry. All-Russian Scientific-Research Institute of Synthetic Fibres, Tver'. Translated fromKhimicheskie Volokna, No. 1, pp. 19–22, January–February, 2000.     

Preparation of polyarylacetylene fibres by the wet spinning method

Conclusions The solvating power of various solvents for poly-p-diethynylbenzene ahs been evaluated by IR spectroscopy.Polyarylacetylene fibres have been prepared by spinning from amide solvents into an aqueous precipitation bath.Translated from Khimicheskie Volokna, No. 6, pp. 33–34, November–December, 1984.     

Resonance in stretching during the process of spinning fibres from solutions of rigid-chain polymers

Conclusions In spinning from sulfuric acid solutions of poly-p-phenylene-1,3,4-oxadiazole and poly-p-phenyleneterephthalamide, the phenomenon of a periodic pulsation in the diameter of the spun monofilament (stretch resonance) is observed. Resonance parameters have been obtained using a series of model channels having different ratios of length to diameter and different forms of the entrance zone as spinnerets.The moment of onset of resonance is determined by the conditions of flow in the channel.The phenomenon of resonance in stretching probably arises because of the action of hydrodynamic resistance forces at the site of contact of the jet with the precipitation bath surface.Translated from Khimicheskie Volokna, No. 2, pp. 29–30, March–April, 1983.     

原位聚合熔体直纺全消光涤纶POY生产工艺探讨

在聚对苯二甲酸乙二醇酯(PET)聚合过程中,将二氧化钛/乙二醇(TiO2/EG)溶液通过添加剂喷嘴加入PET齐聚物管线中,经缩聚得到全消光PET熔体,然后通过熔体直接纺丝、冷却、上油和卷绕,生产92 dtex/72 f细旦全消光涤纶预取向丝(POY),探讨了TiO2/EG溶液浓度、聚合及纺丝工艺对生产稳定性及产品质量的...     

Electrochemical assessment of novel misfit Ca-cobaltite-based composite SOFC cathodes synthesized by solution blow spinning

A new composite cathode for solid oxide fuel cells based on Ca₃Co₄O₉ (C349) and PrO_x was synthesized using a novel solution blow spinning (SBS) process. It is demonstrated that the presence of PrO_x in this cathode permits a remarkable decrease in total polarisation resistance, by ～15 times, mainly due to improvements in charge transfer and surface exchange processes.