Department of Physical Chemistry, University of Duisburg-Essen, Campus Essen, Schuetzenbahn 70, D-45117 Essen, Germany.
Appl Spectrosc. 2010 Jul;64(7):805-9. doi: 10.1366/000370210791666309.
The effect of molecular weight on the thermal degradation of poly(epsilon-caprolactone) (PCL) was investigated by thermogravimetric analysis in combination with differential thermal analysis and Fourier transform infrared spectroscopy (TGA/DTA/FT-IR). The measurements were made in the temperature range 40-720 degrees C and it was found that PCL undergoes completely different degradation processes in nitrogen and oxygen atmosphere. Thus, in nitrogen atmosphere low molecular weight (M(n) = 10,000 g/mol) PCL (PCL(10k)) decomposed in a three-step mechanism. The evolved gases detected by FT-IR spectroscopy were identified as epsilon-caprolactone, 5-hexenoic acid, CO(2), and methyl pentanoate and traces of H(2)O. In the case of high molecular weight (M(n) = 80,000 g/mol) PCL (PCL(80k)) only a two-step degradation was observed. By FT-IR spectroscopy 5-hexenoic acid, CO(2), H(2)O, and methyl pentanoate were detected as decomposition products. In an oxygen environment, similar degradation products were detected for the different molecular-weight PCLs. The recorded FT-IR spectra of the evolved gases were identified as CO(2), CO, H(2)O, and short-chain carboxylic acids.
采用热重分析（TGA）、差热分析（DTA）和傅里叶变换红外光谱（FT-IR）联用的方法研究了分子量对聚己内酯（PCL）热降解的影响。测量温度范围为 40-720°C，发现PCL 在氮气和氧气气氛中经历完全不同的降解过程。因此，在氮气气氛中，低分子量（M(n) = 10,000 g/mol）的 PCL（PCL(10k)）通过三步机制分解。FT-IR 光谱检测到的挥发气体被鉴定为己内酯、5-己烯酸、CO(2)、甲基戊酸酯和痕量的 H(2)O。对于高分子量（M(n) = 80,000 g/mol）的 PCL（PCL(80k)），仅观察到两步降解。通过 FT-IR 光谱检测到 5-己烯酸、CO(2)、H(2)O 和甲基戊酸酯作为分解产物。在氧气环境中，不同分子量的 PCL 也检测到了相似的降解产物。记录的挥发气体的 FT-IR 光谱被鉴定为 CO(2)、CO、H(2)O 和短链羧酸。
