Assessment of physical changes occurring during conservation treatment, storage and display of cultural artefacts based on cellulosic materials

该研究将专门研究水分含量变化对纤维素物理特性的影响，这可能导致纤维素制品（如纸上的艺术品和民族志文物中的植物材料）的脆性增加。脆性的发展是人工制品保护中的一个主要问题。化学原因已经并将继续被许多保护领域的个人和团体研究，但物理原因的研究要少得多。纤维素的水分含量在水保存处理期间以及在展示和储存物品期间相对湿度波动的结果是已知的。该研究项目将建立在对该领域以前的研究成果进行广泛的文献调查的基础上，将对特定的纤维素材料进行实验室研究，特别是棉絮、软木纸和Raphia植物标本。这些将受到水处理和控制相对湿度波动。这些实验对纤维素特定物理性质的影响将被监测并随后进行分析。研究将集中在两种类型的物理变化相关的发展脆性纤维素，特别是增加结晶度和角化。纤维素部分是结晶的，部分是非结晶的。纤维素的结晶度对纤维素材料的机械性能有重要影响。随着纤维素结晶度的增加，纤维素材料变得更脆。有人建议，湿保存处理可能会增加结晶度，但迄今为止进行的少量研究是矛盾的。另一个可能发生的相关物理变化是角质化——从潮湿状态干燥后水分恢复的减少。在角化发生的地方，脆性会增加。用于研究结晶度变化的实验室技术将是傅里叶变换红外光谱、x射线衍射和差示扫描量热法。将通过测量保水值来研究角质化。人们认为，随着纤维素分子聚合程度（它们的“长度”）的减少，角质化和结晶度的增加更容易发生。这种长度的减少可能是退化的结果。这将通过使用粘度测量技术测量样品的聚合程度来研究。将对结果进行分析，以便确定发生物理变化的难易程度与聚合程度之间的任何相关性。物理变化对被测材料力学性能的影响将通过拉伸试验进行研究。从这项研究中获得的见解将用于发展进一步的研究项目，密切关注各种文化文物。这将有助于开发和完善涉及纤维素材料中水分含量变化的保护和保存协议。

The research will specifically investigate the effects of moisture content changes on physical properties of cellulose which can lead to increasing brittleness of cellulosic artefacts such as works of art on paper and plant materials in ethnographic artefacts. The development of brittleness is a major concern in the conservation of artefacts. Chemical causes have been, and continue to be studied by a number of individuals and groups in the field of conservation but physical causes have been much less extensively studied. The moisture content of cellulose is known to change during aqueous conservation treatments and as a result of relative humidity fluctuations during display and storage of objects. This research project will build on an extensive literature survey of previous research findings in the field, laboratory based research will be carried out on specific cellulosic materials, specifically cotton linters, soft-wood papers and Raphia plant specimens. These will be subjected to aqueous treatments and controlled relative humidity fluctuations. The effects of these experiments on specific physical properties of cellulose will be monitored and subsequently analysed.The research will concentrate on two types of physical change relevant to the development of brittleness in cellulose, specifically increased crystallinity and hornification. Cellulose is partly crystalline and partly non-crystalline. The degree of crystallinity of cellulose has a major effect on the mechanical properties of cellulosic materials. As the crystallinity of cellulose increases, celluosic materials become more brittle. It has been suggested that wet conservation treatments may increase crystallinity but the small amount of research carried out to date is contradictory. Another relevant physical change that may occur is hornification - a decrease in moisture regain following drying from the wet state. Where hornification occurs, brittleness has been found to increase.The laboratory techniques used to investigate changes in crystallinity will be Fourier-transform infra red spectroscopy, x-ray diffraction and differential scanning calorimetry. Hornification will be investigated by measurement of water retention value. It is thought that hornification and crystallinity increases are able to take place more easily as the degree of polymerisation of cellulose molecules (their 'length') decreases. This decrease in length can occur as a result of deterioration. This will be investigated by measuring the degree of polymerisation of samples using viscometric measurement techniques. The results will be analysed in order to locate any correlations between the ease with which physical changes take place and degree of polymerisation. The effects of physical changes on mechanical properties of the materials tested will be investigated by tensile testing.It is intended that insights gained from this research will be used to develop further research projects that closely target a variety of cultural artefacts. This will help to develop and refine conservation and preservation protocols involving moisture content changes in cellulosic materials.