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.

scholarly journals Effect of Different Pressures on Microstructure and Mechanical Performance of F-III Fibers in Supercritical Carbon Dioxide Fluid

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 690 ◽  
Author(s):  
Xiaoma Ding ◽  
Haijuan Kong ◽  
Mengmeng Qiao ◽  
Zhifeng Hu ◽  
Muhuo Yu
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Mechanical Performance ◽  
Treatment Temperature ◽  
Orientation Factor ◽  
X Ray ◽  
X Ray Scattering ◽  
Fibril Length ◽  
Supercritical Carbon ◽  
Ray Scattering

F-III fibers were treated at different pressures in supercritical carbon dioxide fluid and all samples including untreated and treated F-III fibers were characterized by a mechanical performance tester, wide-angle X-ray scattering and small-angle X-ray scattering. By studying the relationship between mechanical performance and microstructural changes of the samples, it was found that microstructural change was the main cause of variation in mechanical performance. Results revealed that the maximum tensile strength and modulus of F-III fibers were acquired at 14 MPa within the pressure range of 8 MPa to 16 MPa when the temperature, tension and time were 250 °C, 6 g·d−1 and 40 min, respectively. Correspondingly, the microstructures of the samples, including the phase fraction, crystal size, orientation factor, fibril radius, fibril length and misorientation angle, have been investigated. It was fortunate that the supercritical carbon dioxide fluid could be used as a medium during the hot-stretch process to improve the mechanical performance of F-III fibers, although the treatment temperature was lower than the glass transition temperature of the F-III fibers.

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.

Aggregation of Amphiphilic Molecules in Supercritical Carbon Dioxide: A Small Angle X-ray Scattering Study

Langmuir ◽  
1995 ◽  
Vol 11 (11) ◽  
pp. 4241-4249 ◽  
Author(s):  
John L. Fulton ◽  
David M. Pfund ◽  
J. B. McClain ◽  
T. J. Romack ◽  
E. E. Maury ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Amphiphilic Molecules ◽  
Scattering Study ◽  
Supercritical Carbon ◽  
Ray Scattering

A combined small-angle neutron and X-ray scattering study of block copolymers micellisation in supercritical carbon dioxide

2003 ◽  
Vol 36 (3) ◽  
pp. 660-663 ◽  
Author(s):  
Fabrizio Lo Celso ◽  
Alessandro Triolo ◽  
Fabio Triolo ◽  
Pappannan Thiyagarajan ◽  
Heinz Amenitsch ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Block Copolymers ◽  
Supercritical Carbon Dioxide ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Supercritical Carbon ◽  
Ray Scattering

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.

Deacidification of Paper Using Supercritical Carbon Dioxide Containing Calcium Propionate or Magnesium Bicarbonate

2013 ◽  
Vol 781-784 ◽  
pp. 2637-2640
Author(s):  
Wei Tan ◽  
Li Fen Cheng ◽  
Yan Xiong Fang
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Treatment Time ◽  
Alkaline Reserve ◽  
Before And After ◽  
Calcium Propionate ◽  
Supercritical Carbon

Supercritical carbon dioxide (SCCO2) containing calcium propionate or magnesium bicarbonate was used to deacidify paper. In the experiment, to compare the effects of SCCO2 technology deacidification and immersion deacidification, two kinds of paper samples were chosen to do these two kinds of deaciditication tests respectively. And pH, alkali reserve and mechanical properties of paper samples were measured before and after these treatments. The experiments showed that the pH and alkaline reserve of paper samples treated with SCCO2 were nearly similar to that of immersion treatments. Otherwise, compared with immersion deacidification, supercritical carbon dioxide had some advantages of strengthening the mechanical properties of paper and shortening treatment time.

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.

Sign in / Sign up

Export Citation Format

Share Document