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

这项研究将专门调查含水率变化对纤维素物理性质的影响，这可能会导致纤维素文物(如纸上的艺术品和人种学文物中的植物材料)的脆性增加。脆性的发展是文物保护中的一个主要问题。保护领域中的一些个人和团体已经并将继续研究化学原因，但对物理原因的研究要少得多。众所周知，纤维素的水分含量在水分保护处理过程中会发生变化，并会由于物品陈列和储存期间的相对湿度波动而发生变化。这一研究项目将建立在对以前实地研究成果的广泛文献调查的基础上，将对特定的纤维素材料，特别是棉花短绒、软木纸张和拉菲亚植物标本进行基于实验室的研究。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。研究将集中在与纤维素脆性发展相关的两种类型的物理变化上，特别是结晶度和角化程度的增加。纤维素部分为晶态，部分为非晶态。纤维素的结晶度对纤维材料的力学性能有很大的影响。随着纤维素结晶度的增加，纤维素材料变得更脆。有人提出，湿法保存处理可能会增加结晶度，但迄今为止开展的少量研究是相互矛盾的。另一个可能发生的相关物理变化是角质化--干燥后从潮湿状态恢复的水分减少。在角质化发生的地方，脆性已被发现增加。用于研究结晶度变化的实验室技术将是傅立叶变换红外光谱、x射线衍射和差示扫描量热法。角质化将通过测量保水值来进行。人们认为，当纤维素分子的聚合度(它们的‘长度’)降低时，角化和结晶度的增加更容易发生。这种长度的减少可能是劣化的结果。这将通过使用粘度测量技术测量样品的聚合度来进行研究。将对结果进行分析，以确定物理变化发生的难易程度与聚合程度之间的任何关联。物理变化对测试材料的机械性能的影响将通过拉伸测试来调查。这项研究的目的是将从这项研究中获得的见解用于开发更多针对各种文化文物的研究项目。这将有助于制定和完善涉及纤维素材料水分含量变化的保存和保存协议。

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.