【摘要】 本文研究了剂量、辐照气氛、升温速率对γ-辐照聚乙烯的热释光曲线的影响。当剂量在9×10~5拉特以下时,在77到273°K 之间出现三个主峯;当增高剂量(2×10~6拉特以上)时则仅呈现二个主峯。低剂量时,氧对释光曲线有显著影响,但对峯Ⅰ(低温峯)则观察不到明显的影响。 在辐照聚乙烯的差热分析中,我们观察到一个由辐照引起的吸热峯。虽然该差热峯的温度位置与释光峯峯Ⅰ相近,但与释光峯在反复辐照时仍可出现的情况相反,在反复测试差热或反复辐照时该吸热峯却不再出现。这表明产生这两种峯的因素不是同一的,而决定这两种峯的温度位置的因素却可能是相同的。 用分峯法将热释光曲线的主峯分开,由此求得峯Ⅰ和峯末的活化能分别为0.22及1.2电子伏;与由变更升温速率法所求得的活化能相比较,对峯末由两种方法所得的结果相近,对峯Ⅰ则相差较大。通过与理论计算曲线相比较,表明分峯法所得的结果较为合理。更多还原

【Abstract】 The effects of irradiation atmosphere, irradiation dose, and heating rate upon the thermoluminescence of γ-irradiated polyethylene sheet were studied. It is found that on the glow curve there appear three main peaks between 77°K and 273°K with irradiation doses up to 9×105 rads, but the number of peaks is reduced to two as the dose is increased to or over 2×106rads. At low irradiation dose, the effect of oxygen is pronounced, while peak I (the low temperature peak) seems to remain unchanged.Furthermore, an endothermal peak with its temperature location close to glow peak Ⅰ, is observed on the DTA (differential thermal analysis) diagram of an irradiated polyethylene powder sample. Contrary to the glow peaks, this endothermal peak disappears after repeated irradiation, even on repeated DTA testing. This indicates that the glow peak I and the endothermal peak are of different origin, but it is considered that the factors determining the temperature locations for the appearance of these two peaks might be the same.By separating the main peaks from each other, the values of activation energy for peak Ⅰ and Ⅲ have been determined to be 0.22 eV and 1.2 eV respectively. However, the value for peak Ⅲ is nearly identical with that obtained by the method of changing heating rate, while the difference between the values for peak I is fairly large. By comparing the experimental curve with the calculated ones, it is shown that the results obtained by the peak-separating method is more reasonable.更多还原