文献类型：期刊文献

英文题名：New Experimental Evidence for Thermodynamic Links to the Kinetic Fragility of Glass-Forming Polymers

作者：Wu, Guozhang[1];Liu, Yuanbiao[1];Shi, Gaopeng[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai Key Lab Adv Polymer Mat, Shanghai 200237, Peoples R China

年份：2021

卷号：54

期号：12

起止页码：5595

外文期刊名：MACROMOLECULES

收录：;EI(收录号：20212610557207);WOS:【SCI-EXPANDED(收录号:WOS:000665741600029)】；

基金：We would like to thank Professor Liming Wang from Yanshan University for his valuable discussion on and kind help in determining the enthalpy relaxation of small molecules CA, xylitol, AO300, and AO1010. This research was financially supported by the National Natural Science Foundation of China (grant numbers 51873063 and 51373053).

语种：英文

外文关键词：Specific heat - Glass - Kinetics - Glass transition - Entropy

摘要：Providing a thermodynamic basis to kinetic fragility has been pursued for decades. This objective is particularly challenging for glass-forming polymers because of the difficulty in gauging configurational excess entropy Delta S-ex. Herein, we report that enthalpy hysteresis Delta H-R determined from a well-defined cooling and subsequent heating cycle of heat capacity curves bears a proportional relationship with alpha-related excess enthalpy at the glass transition temperature (T-g). Correlations of fragility (m(e)) with Delta H-R and heat capacity jump ACp at T-g are explored in a broad range of polymers, including monodispersed polystyrene with a molecular weight of 580-2 400 000, homopolymers with a fragility ranging from SO to 200 and T-g ranging from 200 to >400 K, and copolymers and polymer/small-molecule mixtures with different compositions and varied intermolecular strengths. Surprisingly, all of the presented data follow m(e) = 0.75 Delta Cp.T-g/Delta H-R + 15, a formula that can be theoretically derived Adam-Gibbs equation if the prefactor r o is given at 10(-13) s. These experimental results not only provide a possible routine for estimating the alpha-related excess entropy of noncrystallizable polymers but also validate the thermodynamic link to the kinetic fragility of glass-forming polymers.