Badania nad zastosowaniem celulozy bakteryjnej w konserwacji i restauracji dzieł sztuki

Abstrakt

Bacterial cellulose (BC) obtained in the bacterial biosynthesis by Acetobacter xylinum is considered one of the most interesting materials tested and used in different areas of the human activity. Successful its applications in medicine and food industry launched a study of this material on a large scale. Many characteristic and unique properties of bacterial cellulose are used already in the paper industry Research and application of bacterial cellulose nano fibers made up of cellulose, its non-toxic, biocompatibility and biodegradability fit perfectly into the world of interest and progress in nanotechnology. Plant cellulose and bacterial cellulose have the same chemical structure, but different chemical and physical properties. Bacterial Cellulose is biopolymer not soluble, more elastic and demonstrate a high tensile strength.

The study was performed in collaboration with the Institute of Technical Biochemistry, Technical University of Łódź. Planned and carried out the study covered a wide range of experience of testing the applicability of bacterial cellulose as well as its modification in the work of restoration. So far, studies and practical adaptation of bacterial cellulose in our research are the first tests in the conservation area. The exceptions were the addition of bacterial cellulose sample during the manufacture of paper hand-derived, which as noted have a positive impact on the properties of paper produced and lead to the conclusion that the paper with the participation of bacterial cellulose can be used for archival and preservation purposes. Research undertaken in this study are the first extensive experience seeking to use the unique properties of this material such as high strength and elasticity, content of pure cellulose with a high degree of polymerization and the ability of these material to modification.

Microscopic analysis (SEM, ESEM, AFM) showed significant differences in the structural construction of the test paper and bacterial cellulose (BC). BC is a product of a multi-layered as opposed to a paper test. It consists of a large number of very fine mesh of layers made of the microfibrils, whose thickness is usually tens of nanometers (usually less than 100 nm). Preliminary studies of bacterial cellulose membranes indicated the need to modify the native membrane by drying them to form sheets, and further grinding in the presence of water. Suspensions of bacterial cellulose known in our work hygrogels were modified with the addition of fillers, dyes, methyl cellulose, fibers of paper, fabric and dry shredded leather and parchment. The obtained hydrogels were characterized by low density and high water content, which allowed the formation of thin coats or seams. Additive methylcellulose had a positive influence on the properties of suspensions and coats. Structure of the sheets turned out by use the hydrogels was in contrast to the less dense sheets of BC a more flexible and bibulous.

These suspensions were poured on the low-pressure suction table create flexible, durable sheets with similar appearance to the materials, which were the source fiber supplements. Hydrogels blended well with the fibers of fabrics, leather and parchment response for good and flexible materials. A significant advantage of bacterial cellulose is easy given to maintaining its forms such as impress of the sieve or cloth texture and others.

Sheets of bacterial cellulose, its suspension were used as a bonding agent to reinforcing by coating and lining of test paper. Adhesive properties of hydrogels demonstrated that they can be used as a bonding mediums. Suspensions of bacterial cellulose fibers made from various materials were used for filling the holes in paper, textiles, leather and parchment. Lining samples of Bacterial cellulose sheets did not show any tendency to cracking and tearing. The test paper lining on sheet of BC strengthened the mechanical properties of the test paper. Suspensions of bacterial cellulose fibers used for coating the test paper and tissue samples delicate reinforcing them. Positive effect of application dried sheets to restoration of old photos, application of modified hydrogels to filling and reinforcing the paper and others tested treatment indicate necessary to continue of the evaluation on these field.

Study were performed a wide range of experience. By microscopy examination (SEM, ESEM, OTC) was identified the morphology and structure of the membranes, any modified sheets and products. Colorimetrically determined by the brightness and colors of tested materials. PH and mechanical properties of the membranes, modified sheets and adhesive bonded joints to conservation materials was tested according to Polish standards. Determined mass, thickness, basis weight of the bio-cellulose materials and their changes under influence of the modification applied. Researched the optimal methods of membranes and modified sheets drying. Determined the rate of water vapour transmission according to Polish standards. It was made also evaluation of hygro-stability of the biocellulosic sheets. Biocellulose and test paper changes were studied under the influence of accelerated ageing. The results of investigation indicated that Bacterial Cellulose was more sensitive to microbial attack than the test paper. This characteristic can be improved by application of biocides.