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It has been shown that the free volume fraction at T_g is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at T_g is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at T_g and energy e of rotational isomerization of isolated molecular chains was formulated, e=-k·T_g·In (△α·T_g/1-△α. T_g). The values of calculated from the above formula are in good agreement with those published in the literatures. Thus, the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.7
It has been shown that the free volume fraction at T_g is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at T_g is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at T_g and energy e of rotational isomerization of isolated molecular chains was formulated, e = -k · T_g · The values of calculated from the above formula are in good agreement with those published in the literatures. Thus, the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.7