辐照剂量率对明胶自由基和性能的影响

为探讨剂量率对明胶分子辐照分解的影响机理,采用电子自旋共振(ESR)、凝胶渗透色谱(GPC)等检测技术分析明胶经剂量率为60、480Gy/min 60 Co以及剂量率为12 000Gy/min加速器辐照0~32kGy剂量后,自由基特征、明胶性能与剂量率的关系。结果表明,未辐照明胶ESR信号微弱,三种辐照方式处理后的明胶均呈现相似的ESR双峰特征;相同吸收剂量下,明胶自由基信号强度由大到小依次为60Gy/min 60 Co辐照明胶、480Gy/min 60 Co辐照明胶和12 000Gy/min加速器辐照明胶;60 Co辐照后自由基信号强度(y)与剂量(x)的线性关系为y=26.983x2+1 641.8x-205.69;辐照明胶特性黏度、平均相对分子质量、凝胶强度和断裂伸长率由高到低依次为480Gy/min 60 Co辐照明胶、12 000Gy/min加速器辐照明胶和60Gy/min 60 Co辐照明胶。可见,高剂量率辐照可能减少明胶中有效长寿命自由基的含量,从而抑制明胶辐照灭菌中性能的劣变。

Effect of Dose Rate on Radical and Property of Gelatin

The gelatin was irradiated respectively in the range of 0.32 kGy by dose rates of 60 Gy/min ⁶⁰Co, 480 Gy/min ⁶⁰Co and 12 000 Gy/min accelerator, and the relationships of the radical character and gelatin property with dose rate were investigated through electron spin resonance (ESR) and gelatin permeation chromatogram. The results show that there is weak ESR signal from unirradiated gelatin, but irradiated one presents typical double peak. The order of ESR signal intensity of gelatin with the same absorbed dosage from high to low is 60 Gy/min ⁶⁰Co, 480 Gy/min ⁶⁰Co and 12 000 Gy/min accelerator. The linear relationship between ESR signal intensity from ⁶⁰Co irradiated gelatin and absorbed dose is y=26.983x²+1 641.8x-205.69. The intrinsic viscosity, average relative molecular weight, gelatin strength and breaking elongation of irradiated gelatin from high to low are 480 Gy/min ⁶⁰Co, 12 000 Gy/min accelerator and 60 Gy/min ⁶⁰Co. The protection mechanism of high dose rate radiation on gelatin degradation is that the production of effective long life free radicals reduces.