scholarly journals Effect of Different Pressures of Supercritical Carbon Dioxide on the Microstructure of PAN Fibers during the Hot-Drawing Process

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 403 ◽  
Author(s):  
Mengmeng Qiao ◽  
Haijuan Kong ◽  
Xiaoma Ding ◽  
Zhifeng Hu ◽  
Luwei Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Strength Analysis ◽  
Drawing Process ◽  
X Ray ◽  
Degree Of Orientation ◽  
Hot Drawing ◽  
Pan Fibers ◽  
Supercritical Carbon

The hot-drawing process of polyacrylonitrile (PAN) fibers is an important step during the production of PAN-based carbon fibers. In this study, supercritical carbon dioxide (Sc-CO2) was used as one kind of media for thermal stretching of PAN fibers to study the effect of different pressures of Sc-CO2 on crystallinity, degree of orientation and mechanical property of PAN fibers during the hot-drawing process. The changes of microstructure and mechanical properties in the PAN fibers were investigated by wide-angle X-ray diffraction, small angle X-ray scattering and monofilament strength analysis. The results showed that as the pressure increased, the crystallinity and degree of orientation of PAN fibers increased. Furthermore, when the pressure was 10 MPa, the crystallinity increased from 69.78% to 79.99%, which was the maximum crystallinity among the different pressures. However, when the pressure was further increased, the crystallinity and degree of orientation of the fibers were reduced. The test results of the mechanical properties were consistent with the trends of crystallinity and degree of orientation, showing that when the pressure was 10 MPa, the tensile strength of the fibers increased from 4.59 cN·dtex−1 to 7.06 cN·dtex−1 and the modulus increased from 101.54 cN·dtex−1 to 129.55 cN·dtex−1.

Study on the Crystallization Behavior of PAN Fibers during Hot-Drawing Process in Supercritical Carbon Dioxide Fluid with Different Strain

2020 ◽  
Vol 976 ◽  
pp. 84-89
Author(s):  
Meng Meng Qiao ◽  
Hai Juan Kong ◽  
Xiao Ma Ding ◽  
Zhi Feng Hu ◽  
Mu Huo Yu
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Carbon Fibers ◽  
Crystallization Behavior ◽  
Strength Analysis ◽  
Drawing Process ◽  
Hot Drawing ◽  
Pan Fibers ◽  
Supercritical Carbon

Hot-drawing of polyacrylonitrile (PAN) fibers is an important step in the production of carbon fibers. In this article, we investigated the effect of strain on the crystallization behavior and mechanical properties of PAN fibers treated in supercritical carbon dioxide (Sc-CO2) fluid. We mainly used the methods of X-ray diffraction (XRD), monofilament strength analysis and differential scanning calorimeter (DSC) to study the crystallization behavior, mechanical properties and thermal behavior of PAN fibers during hot-drawing process. The experimental results showed that the crystallinity and mechanical properties of PAN fibers both increased a lot under the action of strain during hot-drawing in Sc-CO2 fluid. This provides an important method for preparation of higher performance PAN precursor for PAN-based carbon fibers.

scholarly journals Study on Crystallization Behaviors and Properties of F-III Fibers during Hot Drawing in Supercritical Carbon Dioxide

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 856 ◽  
Author(s):  
Xiaoma Ding ◽  
Haijuan Kong ◽  
Mengmeng Qiao ◽  
Zhifeng Hu ◽  
Muhuo Yu
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Treatment Time ◽  
Orientation Factor ◽  
X Ray ◽  
X Ray Scattering ◽  
Hot Drawing ◽  
Supercritical Carbon ◽  
Ray Scattering

In order to obtain F-III fibers with high mechanical properties, pristine F-III fibers were hot drawn at the temperature of 250 °C, pressure of 14 MPa, tension of 6 g·d−1, and different times, which were 15 min, 30 min, 45 min, 60 min, 75 min, 90 min, and 105 min, respectively, in supercritical carbon dioxide (Sc-CO2) in this article. All the samples, including the pristine and treated F-III fibers, were characterized by a mechanical performance tester, wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and thermogravimetric analysis (TGA). The results showed that the thermal stability of F-III fibers was enhanced to some extent, and the tensile strength and modulus of F-III fibers had great changes as the extension of treatment time during hot drawing in Sc-CO2, although the treatment temperature was lower than the glass transition temperature (Tg) of F-III fibers. Accordingly, the phase fraction, orientation factor fc of the (110) crystal plane, fibril length lf, and misorientation angle Bφ of all the samples were also investigated. Fortunately, the hot drawing in Sc-CO2 was successfully applied to the preparation of F-III fibers with high mechanical properties.

Relationship between Crystallization Behavior and Mechanical Performance of F-III Fibers under Different Tensions in Supercritical Carbon Dioxide

2020 ◽  
Vol 976 ◽  
pp. 77-83
Author(s):  
Xiao Ma Ding ◽  
Hai Juan Kong ◽  
Meng Meng Qiao ◽  
Zhi Feng Hu ◽  
Mu Huo Yu
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Mechanical Performance ◽  
X Ray Diffraction ◽  
Treatment Mode ◽  
X Ray ◽  
Degree Of Orientation ◽  
Hot Drawing ◽  
New Treatment ◽  
Supercritical Carbon

In this article, the supercritical carbon dioxide (Sc-CO2) was used as a medium for hot-drawing of F-III fibers. The conditions of hot-drawing were selected to be the temperature of 250 °C, pressure of 14 MPa, time of 60 min, and different tensions, which were 0, 3, 4.5, 6, and 7.5 g·d-1, respectively. All samples including the untreated and treated F-III fibers were characterized by a mechanical tester and X-ray diffraction (XRD). Results showed that the Sc-CO2 and applied tension could both promote the crystallinity and degree of orientation of F-III fibers at a temperature below the Tg of F-III fibers in Sc-CO2. Moreover, compared with the untreated, the tensile strength and modulus of treated F-III fibers tended to increase with the increase of tension in the range of 0 ~ 6 g·d-1. In summary, this provided a new treatment mode for the hot-drawing of fibers.

scholarly journals Improving UV Resistance of Aramid Fibers by Simultaneously Synthesizing TiO2 on Their Surfaces and in the Interfaces Between Fibrils/Microfibrils Using Supercritical Carbon Dioxide

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 147 ◽  
Author(s):  
Hui Sun ◽  
Haijuan Kong ◽  
Haiquan Ding ◽  
Qian Xu ◽  
Juan Zeng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Surface Composition ◽  
Fiber Surface ◽  
Synthesis Process ◽  
Uv Resistance ◽  
Aramid Fibers ◽  
X Ray ◽  
Supercritical Carbon

Aramid fibers with low density and high strength, modulus, and thermal resistance are widely used in applications such as bulletproof vests and cables. However, owing to their chemical structure, they are sensitive to ultraviolet light, which degrades the fibers’ useful mechanical properties. In this study, titanium dioxide (TiO2) nanoparticles were synthesized both on the aramid III fiber surface and in the interfacial space between the fibrils/microfibrils in supercritical carbon dioxide (scCO2) to improve the UV resistance of aramid fibers. The effects of scCO2 treatment pressure on the TiO2 structure, morphology, surface composition, thermal stability, photostability, and mechanical properties were investigated using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy, and single-fiber test. The results show that amorphous TiO2 formed on the fiber surface and the interface between fibrils/microfibrils, and decreased the photodegradation rate of the aramid III fiber. Moreover, this modification can also improve the tensile strength via treatment at low temperature and without the use of a solvent. The simple synthesis process in scCO2, which is scalable, is used for mild modifications with a green solvent, providing a promising technique for synthesizing metal dioxide on polymers.

Enhancement of the Mechanical Properties of PEBAX Graphene Nanocomposite Using Supercritical Fluid Assisted Extrusion Polymer Processing Technique

2017 ◽  
Vol 883 ◽  
pp. 75-84 ◽  
Author(s):  
Nireeksha Karode ◽  
Laurence Fitzhenry ◽  
Siobhán Matthews ◽  
Philip Walsh ◽  
Austin Coffey
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Mechanical Performance ◽  
Mechanical Analysis ◽  
Polymer Processing ◽  
Processing Technique ◽  
Graphene Nanocomposites ◽  
Mechanical Tensile ◽  
Supercritical Carbon

Medical tubing used in minimally invasive devices presents a number of design considerations depending on the material used, design requirements (such as sufficient stiffness, flexibility and biocompatibility) and processing conditions. Currently, manufacturing industries adopt co-extrusion systems to meet design specifications, by using multilayer configuration leading to higher cost per device and increased complexity. This paper investigates the mechanical performance of nanocomposites using supercritical carbon dioxide assisted polymer processing technique. The use of innovative medical compounds such as PEBAX graphene nanocomposites have resulted in measurable improvements in mechanical properties. This study also presents the effect of supercritical carbon dioxide on the mechanical and physical properties of the polymer matrix. The mechanical properties have been investigated using dynamic mechanical analysis (DMA) and mechanical tensile test, where sufficient reinforcement was observed depending on the composition of graphene within PEBAX matrix. ATR-FTIR was used to further analyze the effect of supercritical carbon dioxide and interactions within the polymer composite matrix.

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