The Immediate Impact of Aqueous Treatments on the Strenght of Paper
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| Online Access: | http://www.viks.sk/chk/res_3_03_160_177.doc |
| Abstract: | SUMMARIES. The impact of aqueous treatments on the strength properties of Whatman filter paper and five historic papers were investigated. The results showed the statistically significant decrease of tensile strength of Whatman paper and four of the historic papers due to the treatments. They also showed mixed trends concerning folding endurance and tensile energy absorption. Possible explanations for the strength decrease are proposed and long-term implications are discussed on the basis of different strength decrease scenarios. It is suggested that aqueous treatments should be applied only when necessary and that they should be followed by consolidation. The importance of strength and especially tensile tests is emphasized, as they can register changes that cannot be detected by chemical methods. It is suggested that the lack of a preconditioning step can result in misleading conclusions concerning die folding endurance of treated samples. CONCLUSION. Based on our research and literature, we postulate that aqueous treatments could, at least in some cases decrease the strength of paper, especially tensile strength. It is well known that tensile test is insensitive to accelerated ageing. It is very sensitive, however, to changes caused by aqueous treatments, which may indicate either the removal of size and/or structural damage of the cellulose. Therefore, we consider tensile strengdi testing to be equally as important as folding endurance, tensile energy absorption and tearing resistance tests, especially for the evaluation of the immediate impact of washing and aqueous and non-aqueous deacidification. We also think that mechanical strength tests are indispensable, since there are changes after aqueous treatments that cannot be detected by chemical tests such as the determination of the degree of polymerization of cellulose. We propose that aqueous treatments should be applied only when necessary, i.e. mainly with acidic paper, and that they should be followed by resizing. We emphasize the importance of preconditioning before testing mechanical properties, and especially when folding endurance data found before and after aqueous treatments are to be compared. Finally, the remarkable folding endurance values of papers A and C must be emphasized. Although these two papers are at least 300 years old, they are still in perfect condition, a confirmation that good raw material (cotton rag), patient processing and gelatine sizing are the main prerequisites for paper quality. We believe that research has to be done in developing criteria for the interpretation of strength property data of paper after aqueous treatments. Paper B for instance, whose folding endurance definitely increased after deacidification, was highly acidic and significantly thicker than the other papers. The need for nondestructive strength tests was also made clear in this study, since such a test would resolve the uncertainty of the outcome of an aqueous treatment on any paper object. |
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| ISSN: | ISSN 0034-5806 |
