This work is devoted to investigate novel aspects of the rheological and optical response of hydroxypropyl methylcellulose (HPMC) as a result of temperature variations from 308.15 to 338.15 K. First, new insights on correlation between the solution flow behavior and the film thickness uniformity, under distinct temperatures, are established. Then, the HPMC film is examined from the point of view of some basic surface parameters describing the surface morphology, such as root mean square roughness, surface area ratio, texture direction index, kurtosis, skewness and surface bearing index. The refraction properties of HPMC are reported for the first time as a function of wavelength and temperature. The changes in the optical dispersion parameters as a function of temperature increase reveal the reduction of strength of interband optical transitions from 15.147 to 14.086 eV and a smaller band gap from 6.475 to 6.137 eV. The latter is caused by temperature-induced dilatation of the polymer lattice and its effect on the electron–lattice interactions. The thermo-optic coefficient of HPMC is found to be larger than that of other polymers, while its dependence on the wavelength is small, varying from −2.03 × 10⁻⁴ K⁻¹ at 489 nm to −2.31 × 10⁻⁴ K⁻¹. The resulted properties are corresponding to the demands imposed for materials used in optical switching based on thermo-optical effect.

中文翻译：

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基于热光效应的光开关变温下羟丙基甲基纤维素的流变学和光学响应

这项工作致力于研究由于温度从 308.15 到 338.15 K 的变化，羟丙基甲基纤维素 (HPMC) 的流变学和光学响应的​​新方面。首先，对溶液流动行为与薄膜厚度均匀性之间相关性的新见解，在不同的温度，建立。然后，从描述表面形态的一些基本表面参数的角度对 HPMC 薄膜进行了检查，例如均方根粗糙度、表面积比、纹理方向指数、峰度、偏度和表面承载指数。HPMC 的折射特性首次被报道为波长和温度的函数。光学色散参数随温度升高的变化表明带间光学跃迁强度从 15.147 降低到 14.086 eV，带隙从 6.475 降低到 6.137 eV。后者是由温度引起的聚合物晶格膨胀及其对电子-晶格相互作用的影响引起的。发现 HPMC 的热光系数大于其他聚合物的热光系数，同时它对波长的依赖性很小，从 -2.03 × 10⁻⁴  K ⁻¹在 489 nm 至 −2.31 × 10 ⁻⁴  K ⁻¹。所得特性符合对基于热光效应的光开关中使用的材料的要求。