不同聚合度EVOH降解行为研究

利用溶度分级原理对乙烯-乙烯醇共聚物(EVOH)商品料进行分级,获得乙烯含量接近、聚合度不同的四个级分,并采用200℃热氧处理0~40 min的方法对不同聚合度样品进行热氧处理。通过核磁共振氢谱(H NMR)、特性黏数、差示扫描量热仪(DSC)表征了样品结构信息,采用热重分析(TGA)对比不同聚合度样品的热稳定性差异。利用傅里叶变换衰减全反射红外光谱法(ATR-FTIR)、紫外光谱(UV)表达不同聚合度样品在热氧处理过程中的结构变化。实验发现,四个样品在热氧处理过程中,O-H的含量都在减少,C=O与共轭双键的含量不断增加,并且聚合度高的样品更容易生成共轭双键,聚合度低的样品更容易生成C=O。

Study on Degradation Behavior of EVOH with Different Polymerization Degrees

The four components with the similar ethylene contents and different polymerization degrees were obtained from the commercial materials of ethylene vinyl alcohol copolymer( EVOH) by the method of solubility fractionation. Samples with different degrees of polymerization were subjected to thermo-oxidative treatment at 200 ℃ for 0 to 40 minutes. The structure information of the samples was characterized by nuclear magnetic resonance spectroscopy( H NMR),intrinsic viscosity,differential scanning calorimetry(DSC),and the thermal stability of samples with different polymerization degrees was compared by thermogravimetric analysis( TGA).Attenuated total reflection Flourier transformed infrared spectroscopy( ATR-FTIR) and ultraviolet spectroscopy( UV) were used to express the structural changes of samples with different degrees of polymerization during thermal-oxidative treatment. It is found that the content of O-H decreases in the four samples during the thermal-oxidative treatment,and the content of C=O and conjugated double bonds increases,and the sample with high degree of polymerization is more likely to generate conjugate double bond,samples with low degree of polymerization are easier to generate C=O.