小分子玻璃体系结构弛豫非线性特征的焓弛豫研究

发布时间：2018-09-02 09:36

【摘要】：为了解玻璃化转变过程中非线性特征参数的变化规律及与其它特征参数的关联,探讨非线性参数与玻璃态材料热稳定性间的关联,本文利用差示扫描量热仪对具有玻璃形成能力的单质液体、不同混合模式的三种二元混合溶液(间甲基苯甲酸甲酯和邻甲基苯甲酸甲酯、间甲基苯甲酸甲酯与邻苯二甲酸二丁酯、1,2-丙二醇和2-乙基己胺)、三乙酰甘油酯和丙三醇玻璃态中的等温结构弛豫进行了量热学测量,结合Tool-Narayanaswamy-Moynihan-Hodge(TNMH)方程、Kohlrausch-Williams-Watts(KWW)方程和Richert方程对实验结果进行了拟合分析。对具有不同液体强弱性参数、同分异构体分子、具有不同官能团物质等单质液体进行焓弛豫研究,发现同种材料中,当液体强弱性参数变化较大时,非线性参数随着液体强弱性参数的增加而降低。高聚物、无机物和离子液体、金属玻璃等任一类玻璃体系中的结果也符合该规律。还发现通常情况下,材料的非线性参数值小于非指数性参数。利用焓弛豫对理想混合溶液、近似理想混合溶液和非理想混合溶液中的动力学参数随组分的变化进行了分析,发现三种不同混合模式的玻璃形成体系中,非线性参数随组分的偏离方向均与非指数性参数的偏离方向相同,偏离程度的大小受混合热影响。对三乙酰甘油酯和丙三醇在玻璃态下的等温结构弛豫进行焓弛豫研究,利用TNMH方程进行拟合的研究结果表明,非线性参数值是温度时间函数,随着等温时间的延长而变大。利用KWW方程和Richert方程分别进行自由拟合和固定拟合得到的结果表明,利用Richert方程进行固定拟合更加合理,非线性参数随退火温度的降低而变化,同时发现玻璃态下的非指数性参数值不等于玻璃化转变温度处的数值。研究结果有利于估测未知玻璃形成材料的非线性特征参数,评判玻璃形成材料中特征参数计算的准确性;利用二元混合溶液中参数的变化规律,可以外推某些具有低玻璃形成能力材料的动力学特征参数,加深对不易被单独研究玻璃形成材料的认识,指导构建具有特殊动力学特征参数的结构材料;玻璃态下材料等温结构弛豫的研究,有利于认识非线性参数及非指数性参数在整个玻璃化转变温度区间随时间和温度的变化规律,有利于了解玻璃态材料在使用过程中的性能变化,有利于指导构建非线性特征参数与玻璃态材料热稳定性间的关联。
[Abstract]:In order to understand the variation of nonlinear characteristic parameters and their correlation with other characteristic parameters during glass transition, the relationship between nonlinear parameters and thermal stability of glass state materials is discussed. In this paper, differential scanning calorimeter (DSC) was used to treat three binary mixed solutions (methyl m-methylbenzoate and methyl o-methylbenzoate) with glass-forming ability and different mixing modes. The isothermal structural relaxation of methyl m-methylbenzoate, dibutyl phthalate, dibutylene phthalate and 2-ethylhexylamine), triacetylglycerol and glycerol in glass state was measured by calorimetry. The experimental results are fitted with Tool-Narayanaswamy-Moynihan-Hodge (TNMH) equation Kohlrausch-Williams-Watts (KWW) equation and Richert equation. The enthalpy relaxation of simple liquids with different liquid strength parameters, isomer molecules, and different functional groups is studied. It is found that in the same materials, when the liquid strength and weakness parameters change greatly, The nonlinear parameters decrease with the increase of liquid strength. The results in any kind of glass systems such as polymers, inorganic substances, ionic liquids and metallic glasses also accord with this rule. It is also found that, in general, the nonlinear parameter of the material is smaller than that of the non-exponential parameter. The variation of kinetic parameters with components in ideal mixed solution, approximate ideal mixed solution and non ideal mixed solution was analyzed by enthalpy relaxation. The deviation direction of nonlinear parameters with components is the same as that of non-exponential parameters, and the degree of deviation is affected by mixed heat. The isothermal structure relaxation of triacetylglycerol and glycerol in glass state was studied by enthalpy relaxation. The results of fitting by TNMH equation show that the nonlinear parameter value is a temperature time function and increases with the increase of isothermal time. The results of free fitting and fixed fitting with KWW equation and Richert equation show that it is more reasonable to use Richert equation for fixed fitting, and the nonlinear parameters vary with the decrease of annealing temperature. It is also found that the nonexponential parameter values in glass state are not equal to the values at the glass transition temperature. The results are helpful to estimate the nonlinear characteristic parameters of the unknown glass-forming materials, to evaluate the accuracy of the calculation of the characteristic parameters in the glass-forming materials, and to make use of the variation law of the parameters in binary mixed solution. It can extrapolate the kinetic characteristic parameters of some materials with low glass-forming ability, deepen the understanding of the glass-forming materials which are not easy to be studied separately, and guide the construction of structural materials with special dynamic characteristic parameters. The study of isothermal structure relaxation in glass state is beneficial to the understanding of the variation of nonlinear and nonexponential parameters with time and temperature in the whole glass transition temperature range. It is helpful to understand the change of properties of glass state materials in the process of application and to guide the construction of the correlation between nonlinear characteristic parameters and thermal stability of glass state materials.
【学位授予单位】：燕山大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB30

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