Acta Phys. -Chim. Sin. ›› 1996, Vol. 12 ›› Issue (08): 688-692.doi: 10.3866/PKU.WHXB19960804

• ARTICLE • Previous Articles     Next Articles

Phase Transition of Side Chain Liquid Crystal Polyacrylate Studied by Positron Annihilation Lifetime Spectra

Wang Wen-Hua,Wei Long,Zhang Tian-Bao,He Liu,Zhang Shu-Fan,Qi Zong-Neng   

  1. Laboratory of Nuclear Analysis Techniques,Institute of High Energy Physics,Academia Sinica,Beijing 100080|Institute of Chemsitry,Academia Sinica,Beijing 100080
  • Received:1995-12-21 Revised:1996-03-25 Published:1996-08-15
  • Contact: Wei Long

Abstract:

The results of positron annihilation studies on the side-chain polymer liquid crystals were obtained as a function of temperature. It is indicated that thermotropic liquid crystal has two phase transition points near 40℃ and 76℃ respectively. It is suggested that the first phase transition point is correspondent to the melting point of specimen and the second one is clearing point at which liquid crystal phase transits isotropic liquid phase. It can be concluded by the changes of Free-Volume at the phase transition points that the smectic state SA is in better ordered state than the other liquid crystals. The difference in the curves of o-Ps life-time with temperature between the liquid crystal and the liquid crystal polymer was explained.

Key words: Positron annihilation, Liquid crystal polymer, Free-Volume