Kumar Shalvin, Rohindra David, Lata Roselyn, Kuboyama Keiichi, Ougizawa Toshiaki
1 School of Biological and Chemical Sciences, Faculty of Science, Technology and Environment, University of the South Pacific, Private Mail Bag Suva, Fiji.
2 Department of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan.
Appl Spectrosc. 2017 Nov;71(11):2488-2496. doi: 10.1177/0003702817720224. Epub 2017 Jul 11.
This paper investigates the structural changes occurring in poly(trimethylene adipate) (PTAd) and poly(trimethylene succinate) (PTSu) during melt crystallization using differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy. Cooling thermograms revealed that PTAd had a faster crystallization rate than PTSu. Infrared (IR) bands of the two polyesters were assigned by correlating with the IR bands of polymers containing the trimethylene and the diacid segments. The bands at 1478, 1459, 1393, and 1364 cm in PTAd and 1475, 1459, 1393, and 1361 cm in PTSu were designated to the CH of the trimethylene segment. Changes in the IR band absorbance intensities of the CH and the C-O-C groups were monitored with time during melt crystallization. Structural changes of the trimethylene and diacid segments of PTAd occurred synchronously, while in PTSu the two segments changed sequentially. Normalized band intensities showed a time lag between the trimethylene and succinic acid segments. The acid segment showed a faster change compared to the trimethylene segment. Fourier transform infrared spectroscopy is shown to be a useful technique to study conformational changes during crystallization in polymers.
本文采用差示扫描量热法（DSC）和原位傅里叶变换红外（FT-IR）光谱法研究了聚己二酸丙二醇酯（PTAd）和聚丁二酸丙二醇酯（PTSu）在熔融结晶过程中发生的结构变化。冷却热分析图表明，PTAd的结晶速率比PTSu快。通过将两种聚酯的红外（IR）谱带与含有丙二醇链段和二酸链段的聚合物的IR谱带相关联来进行归属。PTAd中1478、1459、1393和1364 cm处以及PTSu中1475、1459, 1393和1361 cm处的谱带被指定为丙二醇链段的CH。在熔融结晶过程中，随着时间监测CH和C-O-C基团的IR谱带吸光度强度的变化。PTAd的丙二醇链段和二酸链段的结构变化同步发生，而在PTSu中这两个链段依次变化。归一化谱带强度显示丙二醇链段和琥珀酸链段之间存在时间滞后。与丙二醇链段相比，酸链段变化更快。傅里叶变换红外光谱法被证明是研究聚合物结晶过程中构象变化的一种有用技术。
