Light Induced Degradation of Nitrocellulose Lacquer Thin Films for Conservation of Art Objects

MRS Advances ◽  
2017 ◽  
Vol 2 (63) ◽  
pp. 3951-3957
Author(s):  
Rebekah I. Webster ◽  
H. Francis Webster
Keyword(s):  
Thin Films ◽  
Infrared Spectrum ◽  
Light Exposure ◽  
Reaction Rates ◽  
Primary Decomposition ◽  
Polymeric Coatings ◽  
Metal Artifacts ◽  
Autocatalytic Model ◽  
Art Objects ◽  
Induced Changes

AbstractTo better understand light induced changes in polymeric coatings commonly used to protect metal artifacts, this work details the decomposition of thin (∼100nm) nitrocellulose-based lacquer films on silver, copper, and gold. Samples were exposed to various wavelengths of light including, UVA (∼340nm), UVB (312nm), and UVC (254nm), under controlled temperature and humidity. Decomposition was characterized using reflection absorption spectroscopy (RAS) and monitoring infrared absorbance bands. The loss of NO2 functional groups was observed and the decrease was fit to a simple two step autocatalytic model involving primary and secondary decomposition steps. The decomposition rate under UVC light exposure was rapid and similar for all substrates. Rate constants for the primary and secondary steps were similar in magnitude and only mildly dependent on temperature. For UVB light exposure, all reaction rates were much slower and secondary decomposition was much faster relative to the primary decomposition step. Decomposition under all conditions resulted in the formation of oxidized species with an infrared spectrum similar to that of carboxylic acids.

Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

INDUCED CHANGES OF THERMOTROPIC PROPERTIES OF PHASE TRANSITIONS BETWEEN SMECTIC A MESOPHASE AND ISOTROPIC LIQUID: EFFECT OF SURFACES

2006 ◽  
Vol 20 (14) ◽  
pp. 821-833 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
ŞENER OKTIK
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Phase Transitions ◽  
Isotropic Liquid ◽  
Smectic A ◽  
Phase Transition Temperatures ◽  
Smectic A Phase ◽  
Induced Changes ◽  
Thermotropic Properties

In this work, the effect of thin films on the thermotropic and thermo-optical properties and peculiarities of the phase transitions between the smectic A and isotropic liquid have been investigated. Peculiarities of the heterophase regions of the straight smectic A-isotropic liquid and reverse isotropic liquid-smectic A phase transitions have been studied. Change of morphologic properties of the heterophase regions, shift of the phase transition temperatures and the change of temperature widths of these heterophase regions under thin film influence have been observed.

Light Effects on Food

1990 ◽  
Vol 53 (5) ◽  
pp. 430-440 ◽  
Author(s):  
MIRAY BEKBÖLET
Keyword(s):  
Dairy Products ◽  
Light Exposure ◽  
Meat Products ◽  
Fats And Oils ◽  
Food Groups ◽  
Visual Appearance ◽  
Factors Affecting ◽  
Off Flavors ◽  
Interval Type ◽  
Induced Changes

Current research studies carried out on light-induced changes in dairy products, fats and oils, and meat products are reviewed. General factors affecting thus formed off-flavors in these food groups are the intensity of light, exposure interval, type of packaging, and some specific nutritive constituents. In dairy products, riboflavin degradation, losses of vitamin A and C are the major effects, whereas in fats and oils the effective constituents are ß-carotene, tocopherols, the undesirable flavors being related mainly to photosensitized oxidation. In case of meat products, the visual appearance seems to be the most important effect due to the formation of oxidized pigment metmyoglobin from oxymyoglobin upon light exposure. The effects of packaging materials and types on photooxidation are also being discussed for each of the above three food commodity groups.

Influence of Laser Heat Treatment on Fracture Strength of Ceramic Thin Film

2012 ◽  
Vol 566 ◽  
pp. 145-149
Author(s):  
Hirotaka Tanabe ◽  
Keiji Ogawa ◽  
Yui Izumi ◽  
Tohru Takamatsu ◽  
Heisaburo Nakagawa ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Fracture Strength ◽  
Strength Loss ◽  
Substrate Material ◽  
Laser Quenching ◽  
Ceramic Thin Films ◽  
Film Hardness ◽  
Induced Changes ◽  
Substrate Hardness

In our previous study, it has been shown that improvement of the adhesive strength and substrate hardness of ceramic coated steels without compromising the film hardness can be achieved by applying laser quenching. In the present research, in order to demonstrate further development of this method, the fracture strength of laser-irradiated ceramic thin films (CrAlN, TiAlN and CrN) was investigated by sphere indentation testing. To prevent heat-induced changes in the substrate hardness, a cemented carbide WC-Co rather than steel was used as substrate material. While the fracture strength of each film decreased significantly through furnace heat treatment, it remained almost unchanged in case of the laser irradiated films. Laser quenching has been shown to effectively reduce the fracture strength loss of the ceramic thin films in coated steels.

Hydrostatic-pressure-induced changes of magnetic anisotropy in (Ga, Mn)As thin films

2017 ◽  
Vol 29 (11) ◽  
pp. 115805 ◽  
Author(s):  
Marta Gryglas-Borysiewicz ◽  
Piotr Juszyński ◽  
Adam Kwiatkowski ◽  
Jacek Przybytek ◽  
Janusz Sadowski ◽  
...  
Keyword(s):  
Thin Films ◽  
Hydrostatic Pressure ◽  
Magnetic Anisotropy ◽  
Induced Changes

Direct quantitative imaging of the writing stage in a photosensitive azopolymer by digital holography

Soft Matter ◽  
2019 ◽  
Vol 15 (39) ◽  
pp. 7809-7813 ◽  
Author(s):  
V. Pagliarulo ◽  
A. Calabuig ◽  
S. Grilli ◽  
P. Ferraro
Keyword(s):  
Thin Films ◽  
Real Time ◽  
Surface Relief ◽  
Digital Holography ◽  
Light Exposure ◽  
Quantitative Imaging ◽  
Continuous Light ◽  
Full Field ◽  
Surface Relief Grating

In this paper, we demonstrated that the gradual formation of a surface relief grating (SRG) in azopolymer thin films under continuous light exposure could be directly observed in situ and in real-time, allowing full-field characterization.

Sign in / Sign up

Export Citation Format

Share Document