Unger Miriam, Morita Shigeaki, Sato Harumi, Ozaki Yukihiro, Siesler Heinz W
Department of Physical Chemistry, University of Duisburg-Essen, Schuetzenbahn 70, 45117 Essen, Germany.
Appl Spectrosc. 2009 Sep;63(9):1034-40. doi: 10.1366/000370209789379240.
In the present study, variable-temperature Fourier transform infrared (FT-IR) spectra of a poly(epsilon-caprolactone) (PCL) homopolymer and a poly(3-hydroxybutyrate) (PHB)-poly(epsilon-caprolactone) (PCL) blend were analyzed by generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy. The C=O stretching vibration bands of PCL and PHB were employed to explore the structural changes in the PCL homopolymer and the PHB-PCL blend during the heating process. For the melting of PCL homopolymer in the temperature range of 50 to 70 degrees C, we observed in the synchronous and asynchronous 2D correlation spectra one crystalline (1724 cm(-1)) and one amorphous (1737 cm(-1)) C=O stretching vibration band, which are also detectable in the one-dimensional FT-IR spectra. This result was also confirmed by PCMW2D correlation spectroscopy. During the heating process of the PHB-PCL blend in the temperature range 30-200 degrees C, the PCMW2D correlation analysis provided detailed information. Thus, in the synchronous PCMW2D correlation spectrum the melting of PCL was observed in the temperature region between 30 and 70 degrees C. The recrystallization of PHB in the blend in the temperature range 70-120 degrees C was accompanied by a shift of the C=O stretching band from higher wavenumber (1724 cm(-1)) corresponding to an imperfect crystalline state to the lower wavenumber (1721 cm(-1)) characteristic of a well-ordered crystalline state. In the temperature range 120-200 degrees C the melting process of PHB in the blend is captured by a sharp transition from the crystalline (1722 cm(-1)) to the amorphous (1747 cm(-1)) C=O stretching band.
在本研究中，通过广义二维相关光谱法（2DCOS）和扰动相关移动窗口二维（PCMW2D）相关光谱法分析了聚（ε-己内酯）（PCL）均聚物和聚（3-羟基丁酸酯）（PHB）-聚（ε-己内酯）（PCL）共混物的变温傅里叶变换红外（FT-IR）光谱。利用PCL和PHB的C=O伸缩振动带，探究了PCL均聚物和PHB-PCL共混物在加热过程中的结构变化。对于PCL均聚物在50至70摄氏度温度范围内的熔融过程，我们在同步和异步二维相关光谱中观察到一个结晶态（1724 cm⁻¹）和一个非晶态（1737 cm⁻¹）的C=O伸缩振动带，这在一维FT-IR光谱中也可检测到。该结果也得到了PCMW2D相关光谱法的证实。在PHB-PCL共混物于30 - 200摄氏度温度范围内的加热过程中，PCMW2D相关分析提供了详细信息。因此，在同步PCMW2D相关光谱中，观察到PCL在30至70摄氏度的温度区域内熔融。共混物中PHB在70 - 120摄氏度温度范围内的重结晶伴随着C=O伸缩带从对应于不完善结晶态的较高波数（1724 cm⁻¹）向有序结晶态特征的较低波数（1721 cm⁻¹）的移动。在120 - 200摄氏度温度范围内，共混物中PHB的熔融过程通过从结晶态（1722 cm⁻¹）到非晶态（1747 cm⁻¹）的C=O伸缩带的急剧转变得以体现。
