喇曼光谱法研究辐照聚合物的气体产值

本文研究了两种典型交联型聚合物在~(60)Coγ射线辐照条件下放出的气体的激光喇曼光谱,通过波数2917cm~(-1),2954cm~(-1)和4157cm~(-1)三处特征谱峰高度与标准谱图的比较,测得辐照聚二甲基硅氧烷放出的各种气体产值:G_(CH_4)=1.05,G_(C_2H_6)=0.23,G_(H_2)=0.58,气体总产值:G_(CH_4-C_2H_6+H_2)=1.86,实验结果表明,在500Mrad剂量以下,辐照样品放出气体的总产值和各种气体的分产值不随剂量而变化,从而给予交联度与剂量成正比以直接证明。用同样方法测得辐照聚乙烯放出的气体产值(G_(CH_2)=2.7),也与辐照剂量无关。

RAMAN SPECTROSCOPIC STUDIES ON GASEOUS YIELD IN IRRADIATION OF POLYMERS

The Raman spectra of gaseous products formed in radiation of twopolymers, polydimethylsiloxane (PDMS) and polyethylene (PE), have been studiedin this paper. They are typical polymers which mainly crosslink during irradiationby ~(60)Co gamma rays. At first, the Raman spectra of pure methane, ethane and hy-drogen were detected in the 50 ml analogue tube (Fig. 1-b), and three spectrum pea-ks at 2917 cm~(- 1), 2954 cm~(-1) and 4157 cm~(-1) were obtained. Their intensities dependingon contents of methane, ethane and hydrogen in the analogue tube are shown in Fig.2. The results prove that intensity of Raman spectra of each gas is only related toits absolute content in the airtight vessel that has fixed volume and is not relatedto other gaseous contents in the same vessel. Then, two grams of PDMS are put ineach of six 50 ml sample tube respectively (Fig. 1 - b) and are radiated by various dosesin vacuum. The Raman spectra of gaseous products formed in radiation of PDMS isshown in Fig. 3. After that, the intertsities of Raman spectra at 2917 cm~(-1), 2954cm~(-1) and 4157 cm~(-1) were compared with each corresponding standard curve in Fig. 2and the amount of each component and total amount of gaseous products produced inirradiation of PDMS were estimated (see Tab. 1). The radiation chemical yields (GValue) for gaseous products formed in radiolysis of PDMS at various doses can becalculated from equation (1) and are given in Tab. 2. The results indicate that theG values of total gaseous products and of each component are not changed with do-ses. The average values of G are G (total) = 1,86; G(CH_4) = 1 .05; G(C_2H_6) = 0,23and G(H_2) = 0,58. From the mechanism of dimolecular reaction, the results given inTab. 2 and Fig. 4 were satisfactorily explained by using dynamic method. Finally,the radiation chemical yield of hydrogen produced in radiolysis of PE is also obtai-ned, G(H_2 ) = 2. 7.