Conformational transitions associated with the deformation of oriented polyethylene fibers

1972 ◽  
Vol 6 (1) ◽  
pp. 160-161 ◽  
Author(s):  
U. G. Gafurov ◽  
I. I. Novak
Keyword(s):  
Conformational Transitions ◽  
Oriented Polyethylene ◽  
Polyethylene Fibers

Study On Polyethylene-Based Carbon Fibers Obtained by Sulfonation Under Hydrostatic Pressure

2021 ◽  
Author(s):  
Jong Hyun Eun ◽  
Joon Seok Lee
Keyword(s):  
Hydrostatic Pressure ◽  
Carbon Fibers ◽  
Tensile Modulus ◽  
Melt Flow Index ◽  
Elastic Behavior ◽  
Flow Index ◽  
Plastic Behavior ◽  
Melt Flow ◽  
Oriented Polyethylene ◽  
Polyethylene Fibers

Abstract Carbon fibers were prepared using polyethylene fibers. The draw ratio of the polyethylene fibers and the sulfonation mechanism were investigated under hydrostatic pressures of 1 and 5 bar. The influence of the melt flow index of polyethylene on the sulfonation reaction was studied. Carbon fibers were prepared through the sulfonation of linear low-density polyethylene (LLDPE) fibers possessing side chains with a high melt flow index. The polyethylene fibers, which exhibited thermoplastic properties and plastic behavior, were cross-linked through the sulfonation process. Their thermal properties and mechanical properties changed to thermoset properties and elastic behavior. Although sulfonation was performed under a hydrostatic pressure of 5 bar, it was difficult to convert the highly oriented polyethylene fibers because of their high crystallinity, but partially oriented polyethylene fibers could be converted to carbon fibers. Therefore, sulfonation was performed using partially oriented LLDPE fibers with a melt flow index of 20 at 130°C for 2.5 hours under a hydrostatic pressure of 5 bar. The resulting fibers were carbonized under the following conditions: 1000°C, 5°C/min, and five minutes. Carbon fibers with a tensile strength of 2.03 GPa, a tensile modulus of 143.63 GPa, and an elongation at break of 1.42% were prepared.

Molecular models for creep in oriented polyethylene fibers

2020 ◽  
Vol 153 (14) ◽  
pp. 144904
Author(s):  
Thomas C. O’Connor ◽  
Mark O. Robbins
Keyword(s):  
Molecular Models ◽  
Oriented Polyethylene ◽  
Polyethylene Fibers

Organoplastics Based on Highly Oriented Polyethylene Fibers

MICC 90 ◽  
1991 ◽  
pp. 740-745
Author(s):  
E. F. Kharchenko ◽  
V. D. Protassov ◽  
A. A. Kulkov ◽  
A. S. Chervyakov
Keyword(s):  
Oriented Polyethylene ◽  
Polyethylene Fibers

scholarly journals Study on polyethylene-based carbon fibers obtained by sulfonation under hydrostatic pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jong Hyun Eun ◽  
Joon Seok Lee
Keyword(s):  
Hydrostatic Pressure ◽  
Carbon Fibers ◽  
Melt Flow Index ◽  
Elastic Behavior ◽  
Flow Index ◽  
Plastic Behavior ◽  
Melt Flow ◽  
Polyethylene Fiber ◽  
Oriented Polyethylene ◽  
Polyethylene Fibers

AbstractPolyethylene based carbon fibers were studied using high density polyethylene(HDPE) fibers and linear low density polyethylene(LLDPE) fibers with various melt flow index. The draw ratio of the polyethylene fibers and the sulfonation mechanism were investigated under hydrostatic pressures of 1 and 5 bar in the first time. The influence of the melt flow index of polyethylene and types of polyethylene fibers on the sulfonation reaction was studied. Carbon fibers were prepared through the sulfonation of LLDPE fibers possessing side chains with a high melt flow index. The polyethylene fibers, which exhibited thermoplastic properties and plastic behavior, were cross-linked through the sulfonation process. Their thermal properties and mechanical properties changed to thermoset properties and elastic behavior. Although sulfonation was performed under a hydrostatic pressure of 5 bar, it was difficult to convert the highly oriented polyethylene fibers because of their high crystallinity, but partially oriented polyethylene fibers could be converted to carbon fibers. Therefore, the effect of fiber orientation on fiber crosslinking, which has not been reported in previous literature, has been studied in detail, and a new method of hydrostatic pressure sulfonation has been successful in thermally stabilizing polyethylene fiber. Hydrostatic sulfonation was performed using partially oriented LLDPE fibers with a melt flow index of 20 at 130 °C for 2.5 h under a hydrostatic pressure of 5 bar. The resulting fibers were carbonized under the following conditions: 1000 °C, 5 °C/min, and five minutes. Carbon fibers with a tensile strength of 2.03 GPa, a tensile modulus of 143.63 GPa, and an elongation at break of 1.42% were prepared.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

Conformational transitions and dynamics of thermal responsive poly(N-isopropylacrylamide) polymers as revealed by molecular simulation

2014 ◽  
Vol 55 ◽  
pp. 153-159 ◽  
Author(s):  
Ming S. Liu ◽  
Cheryl Taylor ◽  
Bill Chong ◽  
Lihui Liu ◽  
Ante Bilic ◽  
...  
Keyword(s):  
Molecular Simulation ◽  
Conformational Transitions
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