Cross-infection in thermo-oxidation of polymers

Evaluation of the deteriorating effects of microbial primary metabolites on silk fibres

The silk biodegradation process remains unclear and requires elucidation with advanced analytical tools. To address this challenge, the role of microbial primary metabolites in the deterioration of ancient silk was investigated using metabolomics and proteomics techniques in this work. The oxalic and palmitic acids were separately identified as the most abundant organic and fatty acid metabolites for silk-fabric deterioration via metabolomics. Proteomics showed that oxalic acid accelerated the degradation of silk proteins, revealing changes at the molecular level in silk. A high concentration of oxalic acid promoted the dissolution of peptides by activating the cleavage activity of various amino acids on the molecular chain of silk protein. Palmitic acid formed sedimentary particulate matter with peptides solubilised from silk proteins, indicating the possibility that traces of ancient-silk proteins remained in the fatty acids. The work presented new techniques and concepts for studying the degradation of historical fabrics and contributed to the proposal of effective measures to prevent microbial attack on silk.

Characterization Techniques of Polymer Aging: From Beginning to End

Polymers have been widely applied in various fields in the daily routines and the manufacturing. Despite the awareness of the aggressive and inevitable aging for the polymers, it still remains a challenge to choose an appropriate characterization strategy for evaluating the aging behaviors. The difficulties lie in the fact that the polymer features from the different aging stages require different characterization methods. In this review, we present an overview of the characterization strategies preferable for the initial, accelerated, and late stages during polymer aging. The optimum strategies have been discussed to characterize the generation of radicals, variation of functional groups, substantial chain scission, formation of low-molecular products, and deterioration in the polymers' macro-performances. In view of the advantages and the limitations of these characterization techniques, their utilization in a strategic approach is considered. In addition, we highlight the structure-property relationship for the aged polymers and provide available guidance for lifetime prediction. This review could allow the readers to be knowledgeable of the features for the polymers in the different aging stages and provide access to choose the optimum characterization techniques. We believe that this review will attract the communities dedicated to materials science and chemistry.

The Effect of Synthetic Polymer Foams on Cellulosic Material Degradation

Polymeric materials are widely used at present as auxiliary materials in the preservation of tangible cultural heritage in museums, galleries, or libraries. The desired properties of such materials include chemical inertness and long lifetime, which are verified by accelerated aging tests. This work has tested three color types of PE foam Plastazote^® LD45 (white, grey, and black), which is recommended for use in the field of cultural heritage preservation. The volatile organic compounds released from the foams after artificial aging and their influence on lignocellulosic materials were investigated. The cellulosic materials were artificially aged in close contact with the foams. All foams released organic acids ranging from acetic acid to hexanoic acid. White foam released organic acids to an extent higher by an order of magnitude compared to the grey and black types. A great influence of white foam on the properties of cellulosic materials was observed. There were large differences in the rate of degradation between the types of foams tested, indicating the need to develop a test method in order to determine the suitability for use in the preservation of culture heritage objects.