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題名 | 玻璃化轉變、大分子纏結與湍流=Glass Transition, Macromolecule Entanglement and Turbulence |
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作者姓名(中文) | 吳嘉麟; 林聖賢; | 書刊名 | 化學 |
卷期 | 57:4 1999.12[民88.12] |
頁次 | 頁267-279 |
分類號 | 333.22 |
關鍵詞 | 玻璃化轉變; 大分子纏結; 湍流; 元激發; Glass transition; Chain entanglement; Turbulence; Elementary excitation; |
語文 | 中文(Chinese) |
中文摘要 | 由多體互作用極化產生的一個空穴Bose子與二個Fermi粒子耦合成大分子體系的 元激發,從微觀尺度到宏觀尺度的反串級運動,揭示了玻璃化轉變的本質。(固→液 ) 玻璃 化轉變就是間歇湍流角色反串現象。熔融轉變就是恰好填滿空間的均勻湍流的角色反串。高 分子纏結現象的本質就是:外力對熔體的任何微擾,都以湍流所具有的反常擴散方式 (比正 常擴散更有效地 ) 向熔體整體輸送動量和能量。纏結的臨界分子量 N �搮奰釧騚欓y的臨界 Rynolds 數Re。所謂纏結結構就是排除體積的分形結構。據此我們對 de Gennes 的 Reptation Model進行修正,導出高分子的融流在纏結下之鬆弛時間 α N �e [1-Tg/Tm] ,其中 Tg、T�o分別為玻璃化溫度和熔融溫度。對柔性高分子而言: α N,與實驗箱符。 本文給出了玻璃化轉變實驗定律,即 WLF 方程的理論證明,和玻璃態離開平衡態後按照 exp[-{t/}] 規律回復的理論證明。 |
英文摘要 | The essence of glass transition can be explained in terms of the elementary excitation and the inverse cascade movement from microscopic to macroscopic scale of the macromolecular system, with coupling of one hole Bose-particle and two Fermi-particles, which are produced by the polarization of many-body potential. In this sense glass transition (Solid → Lquid)is analogous to the phenomenon of role reversal of intermittent turbulence, while melting-transition to the role reversal of turbulence evenly filling the space. The essence of macromolecular entanglement is that, any small disturbance to the melt by external forces transferring momentum and energy to the whole body of the melt by means of an abnormal diffusion (more effective than normal diffusion) through the "turbulence". The critical molecular quantity, N �� ,corresponds to the critical Reynolds number of turbulence, R. The phenomenon of chain entanglement is therefore a display of the fractal structure of excluded volume. Through some modification of de Gennes' reptation model, the formula of macromolecular entanglement is obtained, in which the relaxation time α N �e [1-Tg/T �o ], where Tg and T �o denote glass transition temperature and melting temperature respectively. In the case of flexible macromolecules, this formula, α N, is in better agreement with experimental results. The present model also provides rigorous theoretical bases to the semi-empirical WLF formula and the exponential decay function exp[-{t/} β ], during physical aging. |
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