二醋酸纤维素薄膜剂量计的制备和性能研究

为了改善醋酸纤维素薄膜剂量计在γ辐射剂量测定中稳定性欠佳的问题，拓展其辐射测量应用范围，采用离子液体均相乙酰化纤维素方法制得的二醋酸纤维素（CDA）粉末为原料，优化CDA薄膜制备工艺，研究其γ辐射变色性能及稳定性，制备适用于γ辐射剂量测量且性能优良的CDA薄膜剂量计。基于CDA的辐射变色机理，该薄膜剂量计在270 nm的单位厚度吸光度与吸收剂量存在良好的线性关系，剂量率、CDA的取代度和辐照气氛对薄膜的工作曲线影响较小。CDA薄膜剂量计的剂量检测量程为50~400 kGy，扩展不确定度为8.8%（K=2），辐照后24 h内吸光度测试稳定，具有良好的辐照稳定性，基本满足工业上对于辐射剂量计的使用要求，有望应用于γ辐射剂量的测量。

Fabrication and Property of Film Dosimeter Based on Cellulose Diacetate

The measurement of dose is very important in the radiation physics, radiation chemistry and radiation processing. Cellulose acetate film has been widely used as radiochromic dosimeter in radiation processing with electron beams. However, the common used cellulose acetate film dosimeters are usually influenced by the environmental conditions such as temperature during irradiation, dose rate and post irradiation storage which limited their practical applications. Aiming to improve the stability and application of cellulose acetate film dosimeter during the determination of γ-radiation dose, the cellulose diacetate (CDA) prepared by homogenous acetylation of cellulose in ionic liquids was utilized as raw material, and a clear CDA radiochromic film with good performance was obtained successfully by a casting method. Firstly, the suitable conditions, such as temperature, concentration and drying time for the preparation of CDA film were studied. Furthermore, the gamma radiation effect on the resultant CDA film and stability of radiochromic film during measurement was investigated. Owing to the radiation induced discoloration mechanism of CDA, the absorbance of the CDA film at a wavelength of 270 nm had a good linear relationship with the absorbed dose. The dose rate, the substitution degree of CDA and the irradiation atmosphere had no significant effect on the working curve of the CDA film dosimeter. The range of dose detection was 50-400 kGy, and its extended uncertainty was 8.8% (K=2), with a good measurement stability in 24 h after irradiation. Additionally, the CDA film had good stability during irradiation, the structure and substitution degree of CDA remained unchanged during the irradiation and this can meet the industrial requirements for the radiation dosimeters. The as-prepared cellulose-based radiochromic film is a promising dosimeter for the measurement of γ-ray dose.