乙烯-乙烯醇共聚物(EVOH)的辐射效应研究

Radiation effect of ethylene/vinyl alcohol copolymer

用凝胶抽提、凝胶渗透色谱以及傅立叶变换红外光谱等方法研究了两种乙烯-乙烯醇共聚物(Ethylene-vinylalcoholcopolymers,EVOH)本体和E151/甘油体系的室温辐射效应。在氮气保护下,试样在60Co源中的吸收剂量最高达到1800kGy。结果显示,EVOH在室温下是一种十分难交联的聚合物。E151本体(乙烯醇摩尔分数56%)在吸收剂量达到800kGy时出现痕量凝胶,当吸收剂量增至1200kGy时,体系凝胶含量也只有5.9%。而F101本体(乙烯醇摩尔分数68%)在1800kGy才出现痕量凝胶。造成这两种EVOH的凝胶化剂量不同的原因是乙烯醇基含量不同。EVOH在辐照过程会产生共轭双键,其含量在辐照初期随吸收剂量的增加而增大,达到最大值后随吸收剂量的增加而减少。双键的存在促使EVOH产生了交联。加入增塑剂甘油后,体系在800kGy以前与本体一样无凝胶,而在800kGy之后凝胶含量随着吸收剂量的增大而增大,且比本体E151的凝胶含量值大。

The radiation effect of ethylene-vinyl alcohol copolymer （EVOH）, EVOH/glycerin blend was studied by solvent extraction, gel permeation chromatography （GPC） and Fourier transform infrared spectrum （FTIR） methods. Samples were irradiated up to 1800kGy at room temperature under N2. The results show that degradation is the main reaction in pure EVOH. Trace gel content could be found in E151 irradiated to at least 800kGy, and only 5.9% gel content was found in the sample irradiated to 1200kGy.While trace gel content could be found in F101 irradiated to at least 1800kGy. The different gelation doses of E151 and F101 are due to different contents of vinyl alcohol units. Unsaturation structure can be found in the irradiated EVOH. The content increased at first, and then decreased, with the dose. The existence of double bond enhances the radiation efficiency of EVOH. For EVOH/glycerin blend, the gel content was than that of pure EVOH when the absorbed dose exceeds 800kGy, and the gel content increased with the absorbed dose. But it cannot enhance radiation efficiency of EVOH as water.