Search results for "Wood"

Determining the selective impregnation of waterlogged archaeological woods with poly(ethylene) glycols mixtures by differential scanning calorimetry

2012

The differential scanning calorimetry (DSC) technique was demonstrated to be a reliable and fast tool for the investigation of the selective impregnation of archaeological woods with poly(ethylene) glycols (PEGs) mixtures. To this aim, waterlogged archaeological woods were impregnated by using aqueous mixtures of PEG 4000 and PEG 400 as well as mixtures of these polymers in the melt state. The efficiency of the treatments was also estimated by determining the total consolidant content entrapped into the cavities of degraded wood by means of DSC and thermogravimetry.

Improving the properties of polypropylene–wood flour composites by utilization of maleated adhesion promoters

2007

Polymer composites filled with natural organic fillers have gained a significant interest during the last few years, because of several advantages they can offer compared with properties of inorganic-mineral fillers. However, these composites (based, in most cases, on polyolefins) often show a reduction in some mechanical properties. This is mainly due to the problems regarding dispersion of the polar filler particles in the non-polar polymer matrix and their interfacial adhesion with polymer chains. In this work, polypropylene-wood flour composites were prepared and the effect of the addition of a maleated polypropylene was investigated. The two materials were compounded by an industrial c…

Static and Dynamic Properties of Adsorbed Chains at Surfaces:  Monte Carlo Simulation of a Bead-Spring Model

1996

The adsorption of flexible polymers from dilute solution in good solvents at attractive walls is studied by Monte Carlo simulation of a coarse-grained off-lattice model, varying chain length N and ...

Behavior of carbohydrate-based material in black liquor during heating

2004

One industrial softwood Kraft black liquor was heat-treated (at 175 ?C and 190 ?C for 15-60 min) together with laboratory-made soda-AQ (wheat straw and reed canary grass) and Kraft (reed canary grass) black liquors (at 190 ?C for 30 min). The feedstock black liquors were characterized with respect to their polysaccharide (mainly xylem) and aliphatic carboxylic acid contents before and after the heat treatments. It was noted that, due to the higher amount of polysaccharides in the non-wood black liquors (8.2-16.6% of d.s) compared to that in the softwood black liquor (1.4% of d.s), the heat treatment in the former case resulted in a 5-30% increase in the amount of aliphatic acids formed by v…

Wood coated with plasma-polymer for water repellence

2008

The effects of cold HMDSO and HMDSO + SF6 plasma treatments on spruce, chestnut and poplar wood were investigated in order to obtain a hydrophobic surface evaluated by microscopic, spectroscopic (FT-IR and LIBS) and contact angle analyses. Cold plasma treatments can increase the surface hydro-repellence without modifying the external aspect and bulk properties of different woods.

Trophic habits of Muscardinus avellanarius (Mammalia Gliridae) as revealed by multiple stable isotope analysis

2007

Multiple stable isotope analysis was used to investigate the diet of the common dormouse Muscardinus avellanarius in a mixed Mediterranean forest. δ13C and δ15N values of dormouse tissues compared to those of the vegetal and animal sources available in the area showed that the isotopic composition of both adult and juvenile M. avellanarius could be explained by a mixture of vegetal and animal organic matter. The isotopic composition of the assimilated nitrogen was mostly explained by the organic matter from flora. Among the vegetal components, flowers of Fagus silvatica, Quercus robur, and the rarer Crataegus oxyacantha, berries of Ilex aquifolium and acorns of Q. robur were found in the ad…

Effect of Cd-containing wood ash on the microflora of coniferous forest humus

2000

The use of wood ash in forestry has been questioned because the cadmium (Cd) concentration of ash, which varies between 1 and 20 mg kg(-1) ash, exceeds the level allowed for fertilizers (3 mg kg(-1)) used in agriculture. To investigate the combined and separated effects of Cd and ash on the forest humus microflora, pumice or wood ash, spiked with a water-soluble (CdCl(2)) or -insoluble (CdO) form of Cd at three levels (0, 400 and 1000 mg kg(-1)), were applied at a fertilization level of 5000 kg ha(-1) in a laboratory microcosm study. The trial consisted of 60 microcosms (five replications per treatment), which were incubated in darkness at +20 degrees C and a constant relative air humidity …

Funkcjonalizowane woski polietylenowe jako kompatybilizatory kompozytów polietylenowo-drzewnych o wysokim stopniu napełnienia

2012

Badano proces otrzymywania kompozytów polimerowo-drzewnych o dużym stopniu napełnienia (60-80%), przygotowanych na bazie polietylenu małej gęstości (PE-LD) z udziałem komercyjnej mączki drzewnej (Lignocel C 120 i Arbocel C 320) oraz dodatkiem wosków polietylenowych sfunkcjonalizowanych poprzez ich utlenienie lub szczepienie bezwodnika maleinowego, stosowanych jako czynniki kompatybilizujące. Otrzymane materiały poddano charakterystyce określając ich podstawowe właściwości mechaniczne oraz chłonność wody. Stwierdzono, że nawet niewielka ilość wprowadzonego kompatybilizatora (2,5%), w porównaniu z próbkami otrzymanymi bez jego udziału, w istotny sposób poprawia wytrzymałość kompozytów na zerw…

Psichedelia e cinema

2009

A Methodology for Protection of Trees Against Lightning Strikes as a Measure to Prevent Fires and Loss of Human Life

2021

Some regions may be characterized by a very low annual lightning ground flash density, and yet lightning strikes seem to have been in those areas the cause of widespread wildfires in forested areas. Due to global climate change, these occurrences seem to be an increasing threat. In this paper, the authors discuss the withstand capability of trees against lightning and introduce the criteria for the deployment of tree lightning protection systems (TLPS) to protect forested areas, where deemed necessary by the tree risk assessment. This work analytically identifies the critical trunk radius of the tree below which the tree may explode in the case of a lightning strike and ignite the surroundi…