Gamma Irradiation of Washi \\\\b Part 2: Changes in degree of polymerization and crystallinity of cellulose
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_1_04_40_46.doc |
| Abstract: | SUMMARIES. To simulate the properties of old, i.e. naturally aged paper, so that it would be suitable for the restoration of historical paper objects, modern Japanese paper (Kozo) was subjected to accelerated ageing techniques: thermal ageing at 80°C and 60% RH over periods of 1, 2, 3 and 4 weeks, and irradiation with a cobalt 60 source with doses of 49, 98, 195 and 390 kGy over a total period of 48 hours. During thermal ageing degree of polymerization changed gradually with time, while it changed drastically with increased irradiation dosage. The strength of the samples changed noticeably only when the DP dropped below ca. 700. The crystallinity of kozo fiber was increased by gamma irradiation and thermal ageing, and paralleled the decrease of DP. These changes were most noticeable when irradiation followed thermal ageing. They explain well the decrease of physical strength reported in our previous paper. CONCLUSION. During thermal ageing DP changed gradually with time, while it changed drastically with the increase in radiation dose. The strength of the samples changed noticeably only when the DP dropped below about an average of 700. Crystallinity of kozo fiber increased with gamma irradiation and with thermal ageing, in the same manner as the DP decreased. These changes were most noticeable when irradiation followed thermal ageing. These results explain well the decrease of physical strength as reported in a previous paper11. |
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| ISSN: | ISSN 0034-5806 |
