私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

Links
Contact Info.
  • Address:天津市衛津路94號 南開大學蒙民偉樓222室 204室
  • Zip:300071
  • Tel:022-23498126, 23502411
  • Fax:022-23498126
  • Email:weiwang@nankai.edu.cn
Current Location :> Home > Publications > Text
66. Sequence Distribution Effects on Glass Transition Temperatures of Copolymers: An Extended Gibbs-DiMarzio Equation in View of Bond Rotation Flexibility
writer:Guodong Liu, Zhenying Meng, Wei Wang, Yuelian Zhou, and Liucheng Zhang
keywords:Glass Transition Temperatures; Sequence Distribution Effects; Bond Rotation Flexibility
source:期刊
specific source:The Journal of Physical Chemistry B
Issue time:2008年

In view of bond rotation flexibility and the additivity of stiff energy, a new equation containing mole fractions of sequences and glass transition temperatures (Tg's) of periodic copolymers was proposed. Meanwhile, the effect of stereochemical sequences was also taken into account. Even for the case of all substitutions on primary (C1), second (C2), and third (C3) carbon atoms adjoining to the given bond (triad sequences effect) to be considered, no intractable parameters exist in the new equation if the periodic copolymers of poly[AB], poly[AAB], and poly[BBA] could be acquired. This may facilitate its convenient application in comparison with the Ham equation (Ham, G. E. J. Macromol. Sci. Chem. 1975, A9, 461), which also concerned triad contributions. The new equation was applied to methyl methacrylate-styrene, ethylene-methyl methacrylate, and ethylene-vinyl acetate copolymers, and excellent fittings were obtained. The parameters obtained may predict Tg values of periodic copolymers that have not been acquired as well as provide useful information on the bond rotation flexibility.