Growth of ZnO nanofilms on wood with improved photostability

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Yan Yu ◽  
Zehui Jiang ◽  
Ge Wang ◽  
Ye Song
Keyword(s):  
Solution Treatment ◽  
Treated Wood ◽  
Outdoor Exposure ◽  
Solid Wood ◽  
Zno Films ◽  
Accelerated Weathering ◽  
Step Method ◽  
Major Drawback ◽  
X Ray ◽  
Nano Zinc Oxide

Abstract A major drawback of wood in outdoor exposure is photodegradation of the surface. Nano zinc oxide (ZnO) has been reported to provide enhanced stability of wood against UV degradation. In this study, the formation of ZnO nanostructures on the surface of solid wood was achieved via a simple two-step process consisting of generation of ZnO seeds on the wood surface followed by a solution treatment to promote crystal growth. The morphology and chemical composition of the ZnO films was studied by field-emission scanning electron microscopy combined with energy dispersive X-ray and X-ray diffraction. Accelerated weathering was used to evaluate the photostability of treated wood. The morphology of ZnO nanofilm was dependent on the exposure time in the ZnO seeding solution. Greatly enhanced photostability was achieved with treated wood. UV stability was partially dependent on crystal morphology. This two-step method could probably also be employed to treat other biomaterials with rough surfaces such as bamboo.

Creating water-repellent effects on wood by treatment with silanes

Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Steffen Donath ◽  
Holger Militz ◽  
Carsten Mai
Keyword(s):  
Water Uptake ◽  
Treated Wood ◽  
Solid Wood ◽  
Water Repellent ◽  
Initial Water ◽  
X Ray ◽  
Ray Cells ◽  
Alkoxy Groups ◽  
Water Repellence ◽  
Water Borne

Abstract Three types of silanes were tested for their ability to impart hydrophobicity to solid wood samples: a tetraalkoxy silane bearing four hydrolysable alkoxy groups; two alkyl-trialkoxy silanes; and two multifunctional oligomeric silane systems. The first two types were applied as monomeric silane solutions and pre-condensed sols. The water uptake of treated wood was considerably reduced, especially after treatment with multifunctional water-borne silane systems, while uptake of gaseous water was not changed. Initial water repellence was most pronounced when a fluoro-alkyl functional oligomeric silane system was used; however, after a longer submersion time (24 h), the reduction in water uptake was strongly diminished. Wetting-drying cycles led to a reduction in hydrophobicity of samples treated with sols of alkoxysilanes, while aqueous functional silanes revealed enhanced water-repellent effects after these tests. This was explained by continued condensation of unreacted silanol groups in the aqueous functional silanes during the wetting-drying cycles. X-Ray mapping of silicon (SEM-EDX) showed that the reduction in water uptake due to the multifunctional silane HS 2909 is caused by plugging of the main penetration pathways such as pits, ray cells and ray tracheids.

scholarly journals Comparative chemical investigations of alum treated archaeological wood from various museum collections

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jeannette Jacqueline Łucejko ◽  
Caitlin M. A. McQueen ◽  
Malin Sahlstedt ◽  
Francesca Modugno ◽  
Maria Perla Colombini ◽  
...  
Keyword(s):  
Cultural History ◽  
Inorganic Compounds ◽  
Treated Wood ◽  
Chemical Degradation ◽  
General Level ◽  
History Museum ◽  
X Ray ◽  
Archaeological Wood ◽  
Alum Treatment ◽  
Swedish History

AbstractFrom the mid-1800s to the late 1960s, conservation by alum salts (KAl(SO4)2·12H2O—potassium aluminium sulphate), using various recipes, was a common method to prevent shrinkage and to strengthen waterlogged archaeological wooden objects. This method was mainly used in Scandinavia. The alum method appears to have also been applied to highly degraded archaeological waterlogged wood in other countries, for example in the U.S and Germany. Today, many of the archaeological wooden objects treated with alum show extreme deterioration and very low pH, which are attributed to the effects of the alum-treatment. This study investigated the extent of the current levels of chemical degradation in wooden objects conserved with alum salts at different points in time (1880s, 1930s and 1905–13) in order to understand their current condition and whether extent of degradation was in any way related to time of treatment, in an attempt to understand the rate of degradation. It was also an opportunity to compare the chemical state of preservation of alum-treated wood from different collections, as only the Oseberg collection has been intensively studied in this way up until now. Samples from historical wooden objects from the following collections were investigated and compared: the Dejbjerg collection (National Museum of Denmark in Copenhagen); the Oseberg collection (Museum of Cultural History, Oslo, Norway); the Glimmingehus collection (Swedish History Museum, Sweden). Analyses of lignocellulosic polymers and of inorganic compounds were undertaken to evaluate the chemical preservation of the wooden objects. The investigations were performed using a multi-analytical approach which consisted of: pH measurements, analytical pyrolysis (Py-GC/MS), X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS). It was possible to link the extent of degradation with time, on a general level but we found a great variability in the state of preservation of the wood also within the same collection. It is clear, however that alum-treated wood is more degraded than archaeological wood not treated with alum.

Effect of Solution Treatment on Microstructures and Hardness of Mg-Gd-Y-Zr Alloy

2014 ◽  
Vol 937 ◽  
pp. 182-186
Author(s):  
Quan An Li ◽  
Lei Lei Chen ◽  
Wen Chuang Liu ◽  
Xing Yuan Zhang ◽  
Hui Zhen Jiang
Keyword(s):  
Vickers Hardness ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Hardness Measurement ◽  
Solution Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solution Treated ◽  
Primary Particles ◽  
Zr Alloy

The influence of the solution treatment (at the temperature of 500-520°C for 4-12 h) on microstructures and mechanical properties of Mg-Gd-Y-Zr alloy was investigated by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers hardness measurement. The as-cast alloy contains a microstructure consisting of α-Mg matrix, Mg5Gd phase and Mg24Y5phase. With increasing solution temperature and time, the quantity of the primary particles (Mg5Gd and Mg24Y5) in the alloy continually decreased, and the degree of recrystallization gradually increased, which result in the gradual decrease of the Vickers hardness of the solution-treated alloys.

Properties of Sputter Deposited ZnO Films Co-doped with Lithium and Phosphorus

2013 ◽  
Vol 1494 ◽  
pp. 77-82
Author(s):  
T. N. Oder ◽  
A. Smith ◽  
M. Freeman ◽  
M. McMaster ◽  
B. Cai ◽  
...  
Keyword(s):  
Rf Magnetron Sputtering ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Hall Effect Measurements ◽  
Sputter Deposited ◽  
P Type ◽  
Post Deposition ◽  
Co Doped

ABSTRACTThin films of ZnO co-doped with lithium and phosphorus were deposited on sapphire substrates by RF magnetron sputtering. The films were sequentially deposited from ultra pure ZnO and Li3PO4 solid targets. Post deposition annealing was carried using a rapid thermal processor in O2 and N2 at temperatures ranging from 500 °C to 1000 °C for 3 min. Analyses performed using low temperature photoluminescence spectroscopy measurements reveal luminescence peaks at 3.359, 3.306, 3.245 eV for the co-doped samples. The x-ray diffraction 2θ-scans for all the films showed a single peak at about 34.4° with full width at half maximum of about 0.17°. Hall Effect measurements revealed conductivities that change from p-type to n-type over time.

Synthesis of CaWO4:(Eu3+,Tb3+) Thin Films by a Two-Step Method at Room Temperature

2013 ◽  
Vol 710 ◽  
pp. 170-173
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Composition ◽  
Room Temperature ◽  
Electrochemical Techniques ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize CaWO4:(Eu3+,Tb3+) thin films at room temperature. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that (Eu3+,Tb3+)-doped CaWO4films have a tetragonal phase. When the ratio of n (Eu)/n (Tb) in the solution is up to 3:1, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Tb element; on the contrary, when the ratio in the solution is lower than 1:4, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Eu element. Under the excitation of 242 nm, sharp emission peaks at 612, 543, 489 and 589 nm have been observed for CaWO4:(Eu3+,Tb3+) thin films.

Exposure of Polymeric Glazing Materials Using NREL’s Ultra-Accelerated Weathering System (UAWs)

2010 ◽  
Author(s):  
Carl Bingham ◽  
Gary Jorgensen ◽  
Amy Wylie
Keyword(s):  
Light Intensity ◽  
Thermal Effects ◽  
Outdoor Exposure ◽  
Exposure Chamber ◽  
Accelerated Weathering ◽  
Intensity Level ◽  
Design And Implementation ◽  
Different Temperatures ◽  
Exposure Testing ◽  
Ultraviolet Irradiance

NREL’s Ultra-Accelerated Weathering System (UAWS) selectively reflects and concentrates natural sunlight ultraviolet irradiance below 475 nm onto exposed samples to provide accelerated weathering of materials while keeping samples within realistic temperature limits. This paper will explain the design and implementation of the UAWS which allow it to simulate the effect of years of weathering in weeks of exposure. Exposure chamber design and instrumentation will be discussed for both a prototype UAWS used to test glazing samples as well as a commercial version of UAWS. Candidate polymeric glazing materials have been subjected to accelerated exposure testing at a light intensity level of up to 50 UV suns for an equivalent outdoor exposure in Miami, FL exceeding 15 years. Samples include an impact modified acrylic, fiberglass, and polycarbonate having several thin UV-screening coatings. Concurrent exposure is carried out for identical sample sets at two different temperatures to allow thermal effects to be quantified along with resistance to UV.

scholarly journals Temperate UV-Accelerated Weathering Cycle Combined with HT-GPC Analysis and Drop Point Testing for Determining the Environmental Instability of Polyethylene Films

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2373
Author(s):  
Celine Moreira ◽  
Richard Lloyd ◽  
Gavin Hill ◽  
Florence Huynh ◽  
Ana Trufasila ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Outdoor Exposure ◽  
Accelerated Weathering ◽  
Polyethylene Films ◽  
Parallel Testing ◽  
Mapping Analysis ◽  
Environmental Instability ◽  
Weight Analysis ◽  
Physical Changes ◽  
Ir Spectroscopic

Polyethylene films are one of the most frequently used packaging materials in our society, due to their combination of strength and flexibility. An unintended consequence of this high use has been the ever-increasing accumulation of polyethylene films in the natural environment. Previous attempts to understand their deterioration have either focused on their durability using polymer analysis; or they have focused on changes occurring during outdoor exposure. Herein, this study combines those strategies into one, by studying the chemical and physical changes in the polyethylene structure in a laboratory using molecular weight and IR spectroscopic mapping analysis, combined with temperate UV-accelerated weathering cycles. This approach has been correlated to real-world outdoor exposure timeframes by parallel testing of the sample polyethylene films in Florida and France. The formation of polyethylene microparticles or polyethylene waxes is elucidated through comparison of drop point testing and molecular weight analysis.

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