Brillouin-Rayleigh scattering studies of polypropylene glycol. III
Brillouin-Rayleigh scattering studies of polypropylene glycol. III
复制标题
聚丙二醇的布里渊-瑞利散射研究。
DOI：
10.1063/1.432140
复制
发表时间：
1976
影响因子：
4.4
通讯作者：
Y. Y. Huang
中科院分区：
文献类型：
--
作者：
C. H. Wang;Y. Y. Huang
对平均分子量为1025、2025和4000的聚丙烯乙二醇（PPG）进行了全面的布里渊散射实验研究。得到了不同聚合物的高超声速、衰减系数、弹性模量和朗多-普莱泽克比随温度的变化规律。还包括之前报道的PPG 425数据进行比较。对于所有测量的量，只有劳道-普莱泽克比（低于环境温度）与分子量有关；在目前的425-4000质量范围内，高超声速、衰减系数和弹性模量与分子量无关。不同聚合物之间的朗多-普莱泽克比的差异是由于介质粘度的不同导致了不同程度的冻结密度波动；结构弛豫机制不足以解释各聚合物在常温下的朗多-普拉西克比的增加。
A comprehensive Brillouin scattering experimental study of polypropylene glycol (PPG), average molecular weight of 1025, 2025, and 4000, has been carried out. The hypersonic velocity, attenuation coefficient, the modulus of elasticity, and the Landau–Placzek ratio have been obtained as a function of temperature for each polymer. The PPG 425 data reported earlier are also included for comparison. For all the quantities measured, only the Laudau–Placzek ratio (below ambient temperature) is molecular weight dependent; the hypersonic velocity, attenuation coefficient, and elastic modulus are found to be independent of molecular weight in the present 425–4000 weight range. The differences in the Landau–Placzek ratio between the different polymers are attributed to different degree of frozen‐in density fluctuations due to the difference in the medium’s viscosity; the mechanism of structural relaxation is not sufficient to explain the increase of the Landau–Placzek ratio of each polymer below ambient temperature...