Citation:
FU Tieyuan, MO Zhishen, HAN Ping, QI Yuchen, WU Shuyun, CHEN Donglin. STUDY ON FACTORS AFFECTING ROOM TEMPERATURE TRANSITION OF POLYTETRAFLUOROETHYLENE[J]. Chinese Journal of Polymer Science,
1986, 4(2): 170-179.
STUDY ON FACTORS AFFECTING ROOM TEMPERATURE TRANSITION OF POLYTETRAFLUOROETHYLENE
摘要:
In the X-ray diffiaction intensity distribution diagram of PTFE, three diffraction peaks exist inthe range of Bragg angle 30--45°, which are very sensitive to the Crystal trausition at room temperature.At 15℃, the crystal is triclinic and the "small spikes" along with the main peaks appear on the dif-fraction scans due to the distortion of the unit cell, while at 23℃, distortion no longer exists, "smallspikes" disappear completely. When the temperature is raised to 34℃, the hexagonal crystal fur-ther randomizes and the peak at Bragg angle 42°vanishes.We assigned correctly Miller index(108)to this peak and used 2θ=30-45℃ region("sensitive region") as a criterion to characterize qualitatively the crystal transition.It has been found that some factors such as γ-irradiation,cold pressing,drawing,calendering and copolymerization which are usually encountered in the fabrication or application of PTFE articles have profound effect on the crystal transition as evidenced by X-ray diffraction patterns and DSC thermograms.The information obtained in the present work is beneficial to the use of PTFE articles.
English
STUDY ON FACTORS AFFECTING ROOM TEMPERATURE TRANSITION OF POLYTETRAFLUOROETHYLENE
Abstract:
In the X-ray diffiaction intensity distribution diagram of PTFE, three diffraction peaks exist inthe range of Bragg angle 30--45°, which are very sensitive to the Crystal trausition at room temperature.At 15℃, the crystal is triclinic and the "small spikes" along with the main peaks appear on the dif-fraction scans due to the distortion of the unit cell, while at 23℃, distortion no longer exists, "smallspikes" disappear completely. When the temperature is raised to 34℃, the hexagonal crystal fur-ther randomizes and the peak at Bragg angle 42°vanishes.We assigned correctly Miller index(108)to this peak and used 2θ=30-45℃ region("sensitive region") as a criterion to characterize qualitatively the crystal transition.It has been found that some factors such as γ-irradiation,cold pressing,drawing,calendering and copolymerization which are usually encountered in the fabrication or application of PTFE articles have profound effect on the crystal transition as evidenced by X-ray diffraction patterns and DSC thermograms.The information obtained in the present work is beneficial to the use of PTFE articles.
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