固体表面反射光与其折射指数之间存在余弦函数关系，而折射指数的均方起伏又和固体表面的密度和浓度起伏有关。因此从反射光的变化可以反映材料内部结构的一些变化。基于此理论指导，本文利用同步扫描光谱（SSS ）方法，即荧光光谱仪的同步扫描模式进行反射光的检测，成功地监测了聚己内酯（PCL ）薄膜在铜片上的熔融和非等温结晶过程。PCL薄膜的SSS谱图出现了两个明显的荧光光谱仪的光源峰（467和473 nm ），利用这两个峰的信息可以表征聚合物的熔融和结晶过程中分子链结构的变化。采用SSS方法表征分析得到了PCL的热动力学和结晶动力学参数，其结晶Avrami exponent n为2.8～3.2，平均值为3.1，表明PCL的非等温结晶遵循异相成核、三维球晶生长机理。这些与差示扫描量热仪（DSC）得到的参数一致。研究结果表明SSS方法是一种简单、有效的原位测试聚合物熔融和结晶动态过程的方法。此外，SSS方法是一种基于荧光光谱仪的具有普适性的光谱方法，对发光和不发光固态聚合物均可以检测研究。%There is a cosine function between the reflected light intensity of a solid surface and its refractive in-dex .And the mean squared fluctuation of refractive index is related to fluctuation of density and concentration . So some internal structures changes of materials can be reflected by changes in reflected light .Based on this theory ,the synchronous scanning spectrum (SSS) technique was successfully applied to monitor melting and nonisothermal melt-crystallization of poly (ε-caprolactone) (PCL ) film on a copper substrate .SSS can be im-plemented on a spectrofluorimeter by simultaneously scanning the excitation and emission monochromators (i .e .Δλ=λex -λem =0 nm) .In SSS of PCL films ,two dominant peaks correlated to the light source spectrum of the spectrofluorimeter (at 467 and 473 nm) were used to characterize the macromolecular structure evolution during the melting and nonisothermal melt-crystallization processes .Detailed thermodynamic and crystalliza-tion kinetics parameters obtained by SSS method .The Avrami exponent n obtained by SSS method is in the range of 2.8~3.2 with an average of 3.13 ,illustrating a heterogeneous nucleation process followed by a three-dimensional spherulitic crystal growth mechanism .The crystallization activation energy is -158.2 kJ · mol-1 . These results are in agreement with values determined from differential scanning calorimetry (DSC) method .It indicates that SSS technique is a simple ,effective in situ method for measuring the dynamic melting and crys-tallization process of polymers .Moreover ,the SSS method is a universal spectroscopic technique based on a spectrofluorimeter for monitoring both luminescent and non-luminous solid polymers .
展开▼
