Novel markers to early detect degradation on cellulose nitrate-based heritage at the submicrometer level using synchrotron UV–VIS multispectral luminescence

Cellulose nitrate (CN) is an intrinsically unstable material that puts at risk the preservation of a great variety of objects in heritage collections, also posing threats to human health. For this reason, a detailed investigation of its degradation mechanisms is necessary to develop sustainable conservation strategies. To investigate novel probes of degradation, we implemented deep UV photoluminescence micro spectral-imaging, for the first time, to characterize a corpus of historical systems composed of cellulose nitrate. The analysis of cinematographic films and everyday objects dated from the nineteenth c./early twentieth c. (Perlov's collection), as well as of photo-aged CN and celluloid references allowed the identification of novel markers that correlate with different stages of CN degradation in artworks, providing insight into the role played by plasticizers, fillers, and other additives in stability. By comparison with photoaged references of CN and celluloid (70% CN and 30% camphor), it was possible to correlate camphor concentration with a higher rate of degradation of the cinematographic films. Furthermore, the present study investigates, at the sub-microscale, materials heterogeneity that correlates to the artworks' history, associating the different emission profiles of zinc oxide to specific color formulations used in the late nineteenth and early twentieth centuries.

Preparing For Destruction : A Management Plan For The Los Angeles Police Department's 1925-1939 Collection Of Cellulose Nitrate Negatives

This thesis examines the collection of nitrate negatives produced by the Los Angeles Police Department between the years of 1925 and 1939. The thesis is divided into two sections. The first section contextualizes the collection and explains how a plan was developed for re-photographing, cataloguing, and storing a digital database of the negative collection that will eventually be destroyed. The second section provides a management plan for the collection. Accompanying the management plan is an inventory documenting the current physical condition and the contents of each negative box.

Preparing For Destruction : A Management Plan For The Los Angeles Police Department's 1925-1939 Collection Of Cellulose Nitrate Negatives

This thesis examines the collection of nitrate negatives produced by the Los Angeles Police Department between the years of 1925 and 1939. The thesis is divided into two sections. The first section contextualizes the collection and explains how a plan was developed for re-photographing, cataloguing, and storing a digital database of the negative collection that will eventually be destroyed. The second section provides a management plan for the collection. Accompanying the management plan is an inventory documenting the current physical condition and the contents of each negative box.

Novel Markers to Map and Quantify Degradation on Cellulose Nitrate-Based Heritage: at the Submicrometer Level Using Synchrotron UV-Visible Multispectral Luminescence

Cellulose nitrate (CN) is an intrinsically unstable material that puts at risk the preservation of a great variety of objects in heritage collections, also posing threats to human health. For this reason, a detailed investigation of its degradation mechanisms is necessary to develop sustainable conservation strategies. To investigate novel probes of degradation, we implemented deep UV photoluminescence micro spectral-imaging, for the first time, to characterize a corpus of historical systems composed of cellulose nitrate. The analysis of cinematographic films and everyday objects dated from the 19th c. / early 20th c. (Perlov's collection), as well as of photo-aged CN and celluloid references allowed the identification of novel markers that correlate with different phases of CN degradation in artworks, providing insight into the role played by plasticizers, fillers, and other additives instability. By comparison with photoaged references of CN and celluloid (70% CN and 30% camphor), it was possible to correlate camphor concentration with a higher rate of degradation of the cinematographic films. Furthermore, the present study investigates, at the sub-microscale, materials heterogeneity that correlates to the artworks' history, associating the different emission profiles of zinc oxide to specific color formulations used in the late 19th and early 20th centuries.

INVESTIGATION OF REACTIONS OF INTERACTION OF CELLULOSE NITRIC ESTERS WITH CARBOXYLIC ACID CHLORIDES

The chemical interaction of high-nitrogen cellulose ether with acetic, propionic, butyric and isobutyric acids has been studied. The general laws and features of the electrophilic substitution of functional groups of cellulose nitroesters are revealed. The preferred directions of the chemical interaction of cellulose nitrate with carboxylic acid chlorides are established: O-acylation of nitrate and hydroxyl groups; O-acylation of the glucopyranose ring; O-acylation of the ether bond with depolymerization of the chain of an SC molecule; hydrolysis of nitrate groups; destruction of the chain of a macromolecule of nitric acid ester with the formation of water-soluble organic compounds. The structure, properties and possibilities of using synthesized mixed cellulose ethers were studied. Effective methods have been developed for the chemical modification of cellulose nitrates with carboxylic acid chlorides. The probable directions of the reaction of the interaction of cellulose nitrates with electrophilic reagents are predicted based on quantum-chemical calculations of point charges on the atoms of the reacting molecules. The reactivity of highly substituted cellulose nitrates in reactions with carboxylic acid chlorides has been established. The optimal conditions for the interaction of cellulose nitrates with carboxylic acid chlorides have been identified and a mathematical model of the reaction kinetics has been constructed. The possibility of a directed change in the composition of chemically modified cellulose nitrates depending on the synthesis conditions has been established. As a result of the combined use of physicochemical research methods, the chemical composition was determined and the structure of the synthesized compounds was determined: cellulose acetyl nitrates, cellulose propionyl nitrates, cellulose butyryl nitrates, and cellulose isobutyryl nitrates. Using gel chromatography, it was found that the molecular weight characteristics of the synthesized samples are directly dependent on the conditions of their synthesis. It was found that electrophilic substitution of the functional groups of cellulose nitrate proceeds more intensively in the pyridine medium.

Conversion of Bacterial Cellulose to Cellulose Nitrate with High Nitrogen Content as Propellant Ingredient

Cellulose nitrate has attracted great interest amongst researchers due to its uses in wide range of products including paint and gun propellant. Therefore, this work focuses on the synthesis of cellulose nitrate from two different sources of cellulose; plant and bacterial, in order to obtain high percentage of nitrogen content hence suitable for propellant application. The synthesis of cellulose nitrate was carried out via nitration method using nata de coco and kapok (Ceiba pentadra L) as a raw materials of cellulose. The samples were then characterized by elemental analysis, fourier transform infrared (FTIR) spectroscopy, x-ray diffraction and surface electron morphology (SEM). FTIR analysis showed the presence of NO2 groups in both nitrocellulose proving that nitrocellulose was successfully synthesized by nitration method even though it was produced from different sources of cellulose. It is also showed nitrocellulose with high percentage of nitrogen content was obtained from bacterial cellulose, 12.69% rather than plant cellulose.

Microplastic pollution in the surface waters of creeks along the Kenyan coast, Western Indian Ocean (WIO)

Microplastic pollution has been recognized as a global threat in marine environments and a danger to prey, predators and humans. Yet there have been limited studies in the Western Indian Ocean (WIO) and along the Kenyan coast making it difficult to estimate the extent of such pollution. This is the first study on microplastics (MPs) in the surface waters within creeks (Tudor, Port-Reitz and Mida creeks) in Kenya. Sampling was done in January/ February and September 2018 to collect microplastics from surface water. Neuston nets of 500 μm (large) and 250 μm (medium) size were towed for ten minutes and 50 litres of seawater sieved through a 20 μm net (small) in three replicates. The samples were digested in 10 % Potassium Hydroxide, sieved, and then filtered with cellulose nitrate membrane microfilters. Concentrations of total microplastics, different shapes and colours were established under a microscope. High concentrations of small size (20-250 μm) MPs were encountered and Tudor and Port Reitz had higher concentrations compared to Mida Creek. The study provides data on microplastic concentrations within the creeks and recommends focussing on small size microplastics for monitoring purposes, which due to their high concentrations can be hazardous to organisms.

Modeling of Grinding Technology Fibrous Materials in the Production Process

A comprehensive and systematic analysis of a large amount of experimental data was carried out, and, taking into account the available literature information, the mechanism of the process of grinding fibers of cellulose nitrate materials was revealed. The results obtained are of both scientific and practical interest, since the technological and rheological properties of the target products depend on the quality and nature of the grinding of fibrous materials. The combination of modern methods for studying the degree of dispersion, fractional composition, as well as the structure of fibrous materials during the grinding process, knowledge of the nature of the processing of fibers in various grinding units allow intensifying the grinding technology based on the created original technological scheme of the grinding process. The simulation of the grinding process of fibrous cellulose nitrate materials on the basis of experimental data, which allows predicting the properties of the target product and the creation of waste-free, resource-saving technology for producing materials with improved and adjustable characteristics, is carried out. The adequacy of the created model is shown.