Fixation Property of Copper Triazole Wood Preservatives

According to AWPA E11-2006 standard,copper fixation rates of several copper-based formulations,such as ammoniacal copper,amine copper,and ammoniacal-ethanolamine copper,as well as alkaline copper quaternary(ACQ),were tested and compared in this paper.And the fixation rates of tebuconazole(TEB) and propiconazole(PPZ) in several formulations,such as copper azole,emulsified type and solvent type,were also compared.The determination of copper content in the leachate was analyzed by atomic absorption spectrom...     

Field Trial of Copper Treated Moso Bamboo in Southern China

The field trial of Moso bamboo treated with 9 copper preservatives was conducted in Guangzhou, China. The result showed that two formulations of ammonia-based copper azole (F17 and F18 ) and a formulation of amine copper added with boron (F10), as well as 2 kinds of ammonia-based ACQ, at the copper retention of 3.2 kg/m3 or over, were very resistant to decay and termites after the 5- year field test. And the durability of ACQ-B treated Moso bamboo was similar to that of treated Masson pine and slash pine at...     

Performance of samama (Anthocephalus macrophyllus) LVL based on veneer thickness,juvenile proportion and lay-up

ABSTRACT

A study to determine the quality of laminated veneer lumber (LVL) from samama wood (Anthocephalus macrophyllus) was carried out. Samama is a fast-growing endemic wood in eastern Indonesia. Factorial of three factors in RAL design was used to investigate the influence of veneer thickness, juvenile proportion and veneer lay-up to the quality of the resulted samama LVL. The veneer thicknesses were 1.5 and 3.0?mm. Juvenile proportions were arranged in five levels, which were 100% of juvenile veneer, 100% of mature veneer and combination of both juvenile and mature with juvenile proportion of 14%, 43% and 71%. Two veneer lay-up used in this study were loose side met loose side and tight side met loose side. The result of the study showed various specific gravity of LVL by different proportions of juvenile. This factor also affected the other physical traits. Shear strength of the LVL was equal to the solid wood, yet MOE and MOR were affected by juvenile proportion and veneer lay-up. LVL developed from 100% of mature veneer exhibited the highest MOE and MOR, yet no significant difference was noted in MOE and MOR between LVL 100% of juvenile and other tested juvenile proportions.     

The effects of wood species and treatment retention on kinetics of CCA-C fixation reactions

Reaction kinetics of fixation of CCA-C (chromated copper arsenate type C) preservative was studied at 30°C in ground wood of trembling aspen, red pine, and red maple at treatment retentions of 4.0, 6.4, 9.6, and 30 kg/m³, and red maple pre-extracted with hot water at retentions of 6.4 and 30 kg/m³. Reaction orders of cumulative Cr, Cu, and As reactions decreased gradually during the fixation if calculated by Van’t Hoff’s method. With Essen’s method, CCA fixation was best approximated as follows: Cr—3rd order reaction during the first 24 h, and 1st order reaction for the rest of the fixation period; Cu—2nd order reaction; and As—1st order reaction in red pine and aspen, and 2nd order in red maple. Rates of reaction decreased with increased CCA solution concentration for Cr and Cu, and increased for As, except in red maple. Reaction rates for all CCA elements were significantly higher in rapidly fixing red maple than in regularly fixing red pine and aspen, and were higher in unextracted than pre-extracted red maple. Modeling of CCA fixation kinetic for the whole fixation period enabled comparison of fixation reactions among wood species, preservative components, and treatment retentions.     

Dimensional stabilization of compressed laminated veneer lumber by hot pressing in an airtight frame

Abstract

The purpose of this study was to evaluate the dimensional stability and strength properties of compressed laminated veneer lumber (LVL) produced using a closed hot pressing system. LVL specimens were produced with varying number of veneers using either diphenylmethane diisocyanate (MDI) or a water-soluble phenol formaldehyde (PF) resin at varying temperatures (160–200°C), pressures (0.5–3 MPa) and hot-pressing times (2–16 min). Results show that the heating process decreases the recovery of compressive deformation in the veneers when subjected to cyclic moisture and heat conditions. Thickness swelling was approximately 5% after a drying, wetting and boiling cyclic test for LVL using the MDI resin and hot pressed at 200°C for 8 min. Modulus of elasticity and rupture increased for samples produced in both an open press and the closed press with an increase in the number of veneers and density, as did the absorbed energy in impact bending.     

Dielectric properties of copper-ethanolamine treated Chinese fir (Cunninghamia lanceolata Hook.)

In order to clarify the interaction between copper and wood substances in wood treated with copper containing water-borne wood preservatives, the dielectric constant ε′ and dielectric loss factor ε″ of untreated wood and wood treated with four concentration levels of copper-ethanolamine (Cu-EA) solutions were determined within a temperature range from –100 to 40°C and a frequency range from 100 to 1 MHz. Three dielectric relaxation processes were observed in the ε″ spectrum; among them R-I is based on the reorientation of methylol groups in the amorphous region of wood cell walls and R-II is related to wood extractives. R-III appeared in Cu-EA treated wood, and its magnitude decreases with the concentration of Cu-EA solutions used in this experiment. This relaxation process was considered to be based on the reorientation of copper-ethanolamine-wood complexes in wood cell walls. At low copper retention, the hydrogen in the complex can form hydrogen bonding with adjacent hydroxyl groups, which results in a strong bonding state between copper and wood; at high copper retention, the numerous copper-ethanolamine complexes not only hinder them from forming hydrogen bonding with adjacent wood molecules due to steric hindrance, but also weaken the interaction between wood molecules themselves, which corresponds to reducing ε″ values of both R-I and R-III processes. The results explain the fact of in-creasing copper leaching in wood treated with high concentration copper-based water-borne preservatives.     

Properties of curved laminated veneer lumber made from fast-growing species with radiofrequency heating for use in furniture

Curved laminated veneer lumber (LVL) is manufactured from glue-coated pieces of rotary-cut veneers assembled and pressed between molds. In this study, curved LVLs were produced from two fast-growing wood species such as massion pine (Pinus massoniana Lamb.) and poplar (Populus euramericana CV. I.) for use in furniture. In addition to the applicability of the two wood species used, the optimum technological conditions of curved LVL production with radiofrequency (RF) heating and the physical and mechanical properties of curved LVL were investigated. The results are as follows: (1) Curved LVL made from massion pine and fast-growing poplar shows excellent mechanical properties. These fast-growing wood species are suitable for curved LVL being used as furniture structural members. (2) The mechanical properties of curved LVL are affected by frequency, voltage, RF application time, and moisture content, with the RF application time and moisture content having more important effects on the mechanical properties than the frequency and the voltage. (3) The mechanical properties of curved LVL increase with a linear increase in the density of curved LVL.The abstract of this study was presented at the 9th Annual Meeting of the Chugoku Shikoku Branch of the Japan Wood Research Society, Tottori, October 4, 1997     

Effects of wood species and retention levels on removal of copper,chromium, and arsenic from CCA-treated wood using sodium hypochlorite

Chemical extraction, bioremediation, and electrodialytic processes have been extensively studied for removal of copper, chromium, and arsenic from wood treated with chromated copper arsenate(CCA). However,one problem has not been addressed: the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper,chromium, and arsenic from CCA-treated wood samples using sodium hypochlorite. Our results showed that sodium hypochlorite(Na OCl) was very effective for removal of copper, chromium, and arsenic from CCA-C treated milled wood samples for all three species used in this study. The Cu, Cr, and As extraction efficiencies for red pine were95 % Cu, 97 % Cr and 94 % As, for maple were 95 % Cu,97 % Cr, and 98 % As at 4.0 kg m-3retention levels, and for aspen were 95 % Cu, 92 % Cr, and 91 % As at9.6 kg m-3retention level, respectively. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very important roles in terms of removal of Cu, Cr, and As.     

Forest regeneration 50 years following partial cutting in mixedwood ecosystems of southern Quebec,Canada

The impact of winter harvesting on regeneration 50 years after an experimental diameter-limit cutting was examined in mixed deciduous–coniferous ecosystems of southern Quebec, Canada. The study was conducted in La Mauricie National Park, Quebec, Canada. Regeneration data in two balsam fir (Abies balsamea (L.) Mill.), red spruce (Picea rubens Sarg.), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britt.) ecosystem types were analyzed. Comparisons between uncut and cut stands were obtained from a total of 63 sample plots. For both ecosystems, there were no significant differences between uncut and cut plots for regeneration density and stocking. The most abundant regeneration species were balsam fir, red spruce, sugar maple, red maple (Acer rubrum L.), yellow birch and American beech (Fagus grandifolia Ehrh.). The type of diameter-limit cutting described in the study did not affect regeneration density and stocking but its impact on productivity, timber quality and genetics is still unknown.     

Evolution of CO2 during the fixation of chromium containing wood preservatives on wood

Summary A titration procedure was used to confirm carbon dioxide evolution from wood treated with solutions containing chromic acid and to quantify the effects of species (red pine vs soft maple), solution concentration and reaction temperature on the rate and amount of CO₂ evolved. Small blocks or chips were vacuum treated with either chromated copper arsenate (CCA) wood preservative or chromic acid solutions and the release of CO₂ monitored until the reaction was complete. Significant volumes of CO₂ were measured. This is attributed to the oxidation and subsequent decarboxylation of primary hydroxyl groups on wood constituents. The ratio of moles of CO₂ produced to moles of chromium added to the wood ranged from about 0.07 to 0.24 depending on the wood species, solution properties and fixation conditions. This accounted for from 9 to 32% of the total oxidation potential of the hexavalent chromium applied. The relative amounts of CO₂ produced were higher for maple than for red pine. The rate of CO₂ evolution was also higher in the maple samples, consistent with the higher rate of chromium reduction in soft maple compared to red pine. The amount of C0₂ produced was approximately proportional to the amount of hexavalent chromium in the CCA treating solution although the ratio of CO₂ produced to chromium added to the wood increased slightly with increasing solution concentration. The relative amounts of CO₂ produced increased with increasing fixation temperature over the 50–90 °C range in both species. The rate of CO₂ evolution was accelerated as the fixation temperature was increased. The rates and amounts of CO₂ produced were similar for CCA and Cr0₃ treatments containing the same concentration of chromic acid. Copper and arsenic components of the CCA solution did not appear to have any effect on the decarboxylation reaction.We gratefully acknowledge the financial support of the Natural Sciences and Engineering Research Council of Canada, Natural Resources Canada;, LPB Poles Inc., Masson Quebec, Timber Specialties Ltd., Campbellville Ontario and Guelph Utility Pole Co. Ltd., Guelph Ont. for this study.     

The effect of elevated temperature exposure on the fracture toughness of solid wood and structural wood composites

Fracture toughness of wood and wood composites has traditionally been characterized by a stress intensity factor, an initiation strain energy release rate (G _init) or a total energy to fracture (G _f). These parameters provide incomplete fracture characterization for these materials because the toughness changes as the crack propagates. Thus, for materials such as wood, oriented strand board (OSB), plywood and laminated veneer lumber (LVL), it is essential to characterize the fracture properties during crack propagation by measuring a full crack resistant or R curve. This study used energy methods during crack propagation to measure full R curves and then compared the fracture properties of wood and various wood-based composites such as, OSB, LVL and plywood. The effect of exposure to elevated temperature on fracture properties of these materials was also studied. The steady-state energy release rate (G _SS) of wood was lower than that of wood composites such as LVL, plywood and OSB. The resin in wood composites provides them with a higher fracture toughness compared to solid lumber. Depending upon the internal structure of the material, the mode of failure also varied. With exposure to elevated temperatures, G _SS for all materials decreased while the failure mode remained the same. The scatter associated with conventional bond strength tests, such as internal bond and bond classification tests, renders any statistical comparison using those tests difficult. In contrast, fracture tests with R curve analysis may provide an improved tool for characterization of bond quality in wood composites.     

Moisture storage and transport properties of preservative treated and untreated southern pine wood

Moisture storage and transport properties of southern pine (Pinus spp.) wood were measured for implementation into hygrothermal models. Specimens were untreated or pressure-treated with alkaline copper quaternary (ACQ) preservative. Moisture storage was characterized with sorption isotherms in the hygroscopic region (high capillary pressures) and documented with mercury intrusion porosimetry in the overhygroscopic region (low capillary pressures). The data were then combined into a single moisture retention curve as a function of capillary pressure. Moisture transport was evaluated from steady-state water vapor transmission and dynamic capillary water absorption experiments. These data were used to calculate the moisture permeability over the entire range of capillary pressures using the diffusivity approach of Carmeliet et al. Moisture storage and transport properties were similar for the untreated and ACQ-treated southern pine, except for the permeability of the treated wood which was lower in the radial direction. The data presented here can be used to improve the accuracy of hygrothermal and combined hygrothermal–corrosion modeling simulations.     

Comparative study on physical and mechanical properties of laminated veneer lumber and plywood panels made of wood from fast-growing <Emphasis Type="Italic">Gmelina arborea</Emphasis> trees

Laminated products, such as laminated veneer lumber (LVL) or plywood (PW), have become important recently. The objective of this study was to determine and compare properties of panels fabricated with veneers of Gmelina arborea trees in a fast-growth plantation and glued with phenol formaldehyde resin. The results showed that LVL and PW physical and mechanical properties are comparable to those of solid wood with a specify gravity of 0.60. Moreover, these panels can be cataloged into group 2 of PS 1–95 of the Voluntary Products Standard of the United States. The difference in physical properties was not statistically significant between LVL and PW panels, except for water absorption. Some mechanical properties, such as hardness and glue-line shear, modulus of rupture in perpendicular flexure, nail and screw withdrawal parallel, and perpendicular strength, were statistically different between LVL and PW. However, no differences were established for the modulus of elasticity, tensile strength parallel to the surface, or tensile strength perpendicular to the surface. The differences were attributed to the venners’ orientation in the panels studied.     

Estimating the maple syrup production potential of American forests: an enhanced estimate that accounts for density and accessibility of tappable maple trees

This paper examines the maple syrup production potential of American forests by analyzing Forest Inventory & Analysis (FIA) data provided by the US Forest Service on the resource of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) trees in twenty states. The analysis is based on tree species and size (diameter at breast height, or dbh), ownership category, jurisdiction, the density of maple trees in a stand, and the distance of the stand to an access road. Although there are over 2 billion sugar and red maple trees of tappable size growing in US forests, when narrowed down according to the attributes of an optimal ‘sugarbush’, there are 100 million potential taps from sugar maples alone and 286 million potential taps with sugar and red maples combined. Overall, 45 % of the tappable-size maple trees are found in stands whose density is not high enough to support commercial sap extraction whereas only 6 % are found in stands that are at least 1.6 km from an access road. The ten states with commercial maple syrup industries have a much higher percentage of their maple trees occurring in stands of optimal density and also contain a higher percentage of sugar maple than red maple trees. States that are utilizing the highest percentage of their potential sugarbushes include Vermont and Maine, whereas states that have significant room for expansion include Michigan, New York, and Pennsylvania.     

Identification of gram-positive bacteria isolated from initial stages of wound-initiated discoloration of red maple

Similar gram-positive bacteria in the genera Bacillus and Actinomyces were isolated from sapwood and stage-one discolored wood of red maple. These isolates are unlike those previously reported from red maple wood in advanced decay.     

A Potential Criterion to Evaluate Copper Adsorption in Wood Cell Wall

A gcometrical definition, fractal dimension, was introduced in this study to evaluate copper adsorption in wood treated with copper-containing preservatives. It is based on the assumption that some copper would compete the hydroxyl groups in wood cell wall with water molecules, and therefore influence the fractal dimension of internal wood surfaces revealed by the moisture adsorption in wood. Southern yellow pine (Pinus spp.) specimens were treated with different concentrations of copper ethanolamine (Cu-EA) solution to obtain different copper retention levels. Then the adsorption isotherms of untreated and Cu-EA treated specimens were determined at 4, 15, 30, and 40℃ to provide the source data for fractal dimension calculation. The results showed that, at all temperatures, the fractal dimension of the internal wood surfaces had a decreasing trend with increasing copper retention. That is, the internal spaces in wood become “thinner“ due to the copper adsorption on some hydroxyl groups in wood cell wall. The correlation between the fractal dimension and adsorbed copper ions makes it possible to evaluate the copper adsorption in wood cell wall.     

Adaptive responses of<Emphasis Type="Italic">Acer ginnala,Pyrus ussuriensis and Prunus davidiana</Emphasis> seedlings to soil moisture stress

One-year-old seedlings of Amur maple (Acer ginnala Maxim), Ussurian pear (Pyrus ussuriensis Maxim) and David peach (Prunus davidiana Carr) were planted in pots in greenhouse and treated with four different soil moisture contents (75.0%,61.1%, 46.4% and 35.4%). The results showed that net photosynthesis rate (NPR), transpiration rate (TR) and stomatal conductance (Sc) of seedlings of the three species decreased with the decease of soil moisture content, and Amur maple seedlings had the greatest change in those physiological indices, followed by Ussurian pear, David peach. Amur maple and Ussurian pear seedlings also presented a decrease tendency in water use efficiency (WUE) under lower soil moisture content, whereas this was reversed for David peach. Under water stress the biomass allocation to seedling root had a significant increase for all the experimental species. As to root/shoot ratio, Amur maple seedlings had the biggest increase, while David peach had the smaliest increase. The leaf plasticity of Amur maple seedlings was greater, the leaf size and total leaf area decreased significantly as the stress was intensified. No significant change of leaf size and total leaf area was found in seedlings of Ussurian pear and David peach. It was concluded that Amur maple was more tolerant to soil moisture stress in comparison with David peach and Ussurian pear.     

Dendroecology and species co-existence in an old-growth Quercus–Acer–Tilia talus slope forest in the central Appalachians,USA

Dendroecological techniques were used to examine the disturbance history and patterns of species recruitment in an old-growth Quercus rubra L. (northern red oak)–Acer saccharum Marsh. (sugar maple)–Tilia americana L. (basswood) forest on a steep, talus slope in eastern West Virginia. The forest was uneven-aged as were the populations of red oak. Sugar maple dominated the sapling layer, which comprised little or no basswood and red oak. A compilation of major and moderate releases (indicative of disturbance) in 25 cores revealed single or multiple release events in every decade from 1870–1990. The high elevation of the forest coupled with a fertile sub-soil beneath the talus ameliorated the outwardly harsh conditions of the site, allowing for the domination of typically mesophytic, nutrient demanding tree species. We observed several fire scarred trees as well as extensive small-scale blow-down throughout the forest. Frequent disturbance events were probably crucial to the co-existence and continuous canopy recruitment of the relatively light demanding red oak with highly shade tolerant sugar maple and basswood. The strong successional replacement tendencies of red oak by northern hardwoods noted elsewhere in the eastern US may be less apparent on high elevation, rocky sites in the central Appalachians. Thus, this is a unique case study of long-term red oak domination with later successional species in an old-growth forest.     

Corrosiveness of Copper-based Preservatives to 4 Types of Metals

The corrosive rates of 4 types of metals as well as epoxy-coated metal in a variety of preservatives derived from different copper sources and ingredients were .measured in this paper. The main results show that： CCA is less corrosive to red brass and Q235A steel than other copper formulations; Copper-based preservatives such as ACQ and CuAz derived from basic cupric carbonate or cupric hydroxide are much less corrosive to Q235A steel than those from cupric sulfate; Ethanolamine is less corrosive to Q235A steel than ammonia in ACQ derived from cupric hydroxide, while other ingredients are the same; Epoxy resin coating could be used for protecting red brass, Q235A steel and zinc hotdipped galvanized mild steel from corrosion.     

Biological performance of a formulation containing water-dispersible copper naphthenate and sodium fluoride against decay fungi

ABSTRACT

Two formulations of wood preservative one containing water-dispersible copper naphthenate (CuN) alone and in combination with sodium fluoride (NaF) were used to treat southern pine sapwood blocks to determine the effect of the addition of sodium fluoride in the QNS on the protection against wood decay fungi using laboratory soil block tests following AWPA (American Wood protection Association) standard E10-16 [American Wood Protection Association AWPA-E10. (2016 American Wood Protection Association. (2016) Standard E10-16 Laboratory Method for Evaluating the Decay Resistance of Wood-Based Materials Against Pure Basidiomycete Cultures: Soil/Block Test. [Google Scholar]) Laboratory Method for Evaluating the Decay Resistance of Wood-based Materials Against Pure Basidiomycete Cultures: Soil/Block Test]. The standard consists in exposing treated blocks to pure monoculture of white rot (Irpex lacteus (FP-105915) and Trametes versicolor (R-105)) and brown rot fungi (Gloeophyllum trabeum (Madison 617) and Postia placenta (Madison 698) during a specific period. The weight loss (WL) in percentage of treated blocks was used as an indicator of the biological performance of treated blocks against basidiomycetes at specific retentions. Minimum WL was obtained with blocks treated with the formulation containing mixture of QNS and sodium fluoride with the retention of 0.29?kg/m³ Cu and 0.51?kg/m³ of fluorine in treated blocks. A copper retention of 1.65?kg/m³ from blocks treated with formulations containing only QNS was needed to obtain similar WL to blocks containing blocks Cu++ and F? (fluorine). The lower Cu retention is attributed to a combination of the presence of the fluorine with some toxic activities against bacteria and decay and the interaction of anions fluorine and ionic Cu (II) in the aqueous treating solutions to form more soluble biological toxic hydrate of copper fluoride ((H₂O Cu (II) F2) in treated blocks compared to copper complexes less biological available in water-dispersible CuN-treated bocks.