Your search resulted in 148 documents. Displaying 25 entries per page.
Effect of fiber type and content on the natural durability of wood flour/high density polyethylene composites against rainbow fungus (Coriolus versicolor)
2007 - IRG/WP 07-40387
In order to evaluate the effect of fiber type and content on the natural durability of wood flour/high density polyethylene (HDPE) composites against Coriolus versicolor, samples containing 25% and 50% by weight of various natural fibers and HDPE were selected. Natural fibers included in the study were wood flour, rice hulls, hemp fibers and newsprint. Samples containing 25% and 50% natural fiber had 1% and 2% compatibilizer (Maleic anhydride polyethylene (MAPE), respectively. Physical and mechanical properties of all specimens including water absorption, flexural modulus, flexural strength, impact strength and hardness were determined prior to and after incubation with the fungus for 14 weeks at 25 0C and 75% relative humidity. Weight losses of the specimens were also determined after incubation. Results indicated that samples containing 50% natural fiber were more susceptible to fungal decay as compared with those with 25% fiber. Rice hulls proved to be the most vulnerable natural fibers as nearly all mechanical properties of rice hulls composites significantly declined after contamination by the fungus.
A Karimi, M Tajvidi, S Pourabbasi
Effect of Compatibilizer on the Natural Durability of Wood Flour/High Density Polyethylene Composites Against Rainbow Fungus (Coriolus versicolor)
2007 - IRG/WP 07-40388
To evaluate the effect of compatibilizer on the natural durability of wood flour/high density polyethylene composites against Coriolus versicolor, composites containing 25% and 50% by weight maple wood flour and 1% and 2% compatibilizer (Maleic anhydride polyethylene (MAPE)), respectively, were sampled. Identical specimens of the same composites without the compatibilizer were also prepared. Physical and mechanical properties of all specimens, including water absorption, flexural modulus, flexural strength, impact strength and hardness, were determined prior to and after incubation with the fungus for 14 weeks at 25? and 75% relative humidity. Weight losses of the specimens were also determined after incubation. Results indicated that the compatibilizer had significant effects on the natural durability of the studied composite formulations so that all mechanical properties were affected by the fungus to greater extents in the case of uncompatibilized specimens than the compatibilized ones. Weight loss of the uncompatibilized composites was also higher than that of compatibilized ones. Higher water absorption was observed in all cases after incubation. However, the increase in water absorption was considerably higher in the case of uncompatibilized specimens. POLYM. COMPOS., 28:273–277, 2007. © 2007 Society of Plastics Engineers.Considering little weight reduction of the composites, they are very durable material and their recyclability and biodegradability as compared with composites containing inorganic fibers such as glass fiber, these composites present a promising future in terms both mechanical performance and environmental concerns.
Sara Pourabbasi, A Karimi, D Parsapajouh, M Tajvidi, M Soleymani
Lignin blocking effects on weathering process of wood plastic composites
2010 - IRG/WP 10-40529
The weathering of wood–plastic composites (WPC) causes discoloration which affects their aesthetic aspects. It has been proved that these discolorations are due to lignin degradation. Effects of blocking the susceptible structure of lignin assessed by chemical treatment such as acetylation and methylation are reported in this study. Surface chemical change of wood plastic composite (WPC) formulations based on high density polyethylene (HDPE) were monitored by means of ATR FT-IR spectroscopy and colorimetry. According to the standard ASTM 2565, samples were placed in Atlas Xenon apparatus for 250 hrs and 2000 hrs. The results have shown that methylation and acetylation can photostabilize lignin in short period of times. ATR FT-IR spectra shown that, in long term, none of the treatments could protect lignin degradation, within wood flour. Methylation limited the depth of penetration of weathering and these samples have more lignin content compared to control samples.
P Darabi, A Naghi karimi, S Ahmade Mirshokraie, M-F Thévenon
Durability of a willow/plastic composite mat
2016 - IRG/WP 16-20592
Developing uses for wood wastes could enhance utilization of low value renewable materials while creating opportunities for rural development. Small diameter willow stems have little use in China, but they could be combined with high density polyethylene to create wood plastic composite mats for decorative applications. These mats could be used in exterior, above ground exposures, but would still require some level of resistance to decay and mold. The potential for using desert willow (Salix psammphila) from Inner Mongolia as the supporting material for plastic composite matting was evaluated in decay and mold tests. The resulting mats were highly susceptible to attack by decay fungi, and exhibited susceptibility to mold especially where the willow was exposed on the surface. The results suggest that these products have some potential for applications where they are more protected from moisture but would need supplemental treatment in wetter exposures.
Li Yan, Haiyan Duan, Beizhan Quan, J Cappellazzi, J J Morrell
Accidental mold/termite testing of high density fiberboard (HDF) treated with borates and N’N-naphthaloylhydroxylamine (NHA)
2003 - IRG/WP 03-10462
High density fibreboard (HDF) was made from beech and pine furnish (50:50) and treated with boric acid (0.1-3%), borax (0.1-3%) or N'-N-(1,8-naphthalyl) hydroxylamine (NHA) (0.1-1%) prior to gluing with urea formaldehyde (UF) resin in order to determine resistance to Eastern subterranean termites (Reticulitermes flavipes Kollar), the most economically important termite species in North America. HDF and southern yellow pine (SYP) sapwood specimens were tested in a modified no-choice soil-block test normally used for fungal decay tests for 5 weeks. Within the first week of incubation, all HDF specimens were heavily overgrown with a variety of mold fungi. This same contamination was not seen in regular SYP specimens tested under the same conditions. Mold contamination did not appear to inhibit termite attack in any measurable way. Weight loss in control HDF specimens was 28% after 5 weeks while weight loss in control SYP was 12% under similar test conditions. Selected treatments with boric acid, borax, didecyl dimethyl ammonium chloride (DDAC) and NHA reduced termite attack in HDF and SYP specimens below 5% weight loss. Synergy was not observed for boron containing compounds and NHA. We conclude that i) soil contact accelerates HDF mold contamination and termite damage in the absence of termidicides ii) HDF made with UF is more susceptible to moisture acquisition and mold contamination than SYP iii) NHA does not act as a mildewcide iv) 3% borates retard both mold and termite damage; and v) HDF is less durable, and requires more preservative to protect, than SYP.
S N Kartal, H H Burdsall Jr, F Green III
Social and economocal impact of an extension of service life resulting of an adequate preventive treatment. Application to wooden components used in urban areas with a high density of population
1993 - IRG/WP 93-50001-15
Le document évalue les problèmes rencontrés en zone urbaine pour le sauvetage des constructions: coordination de la lutte, délimination des chantieres et des périmètres d'investigation, nuisances causées par les interventions, risques pour la santé, risques pour l'environnement. Coûts. Comparaison socio-économique du traitement préventif et des interventions à posteriori. Cas particulier du détermitage.
A T De Lelis, G A C Lopez
Problems caused by termites in buildings in the State of Sao Paulo
1976 - IRG/WP 150
Termites are the main insects attacking buildings in the State of Sao Paulo - Brazil. Their attack occurs in wood and wooden materials as well as paper, textile, leather and so on.
M S Cavalcante
Improved equipment and technique for high pressure sap displacement impregnation of natural round wood
1972 - IRG/WP 309
Hitherto the main problem in the practical application of high pressure sap displacement impregnation (HPSD) has been in devising a satisfactory cap. Such a cap must be easily fitted to different size log ends to give a leak proof seal. The present contribution describes a new type of cap and sealing system designed to meet these requirements.
C G W Mason, F B Shorland
Effect of a penta emulsion on the service life of Douglas fir, heartwood posts
1978 - IRG/WP 3112
C S Walters
Changed susceptibility of the chemically and thermally degraded spruce wood to its attack by the dry rot fungus Serpula lacrymans
1999 - IRG/WP 99-10322
In buildings, some intentional or unintended situations can occur at which some wood products are exposed to aggressive chemicals and also to higher temperatures. Occasional activity of fungi on such pre-attacked wood products can be either higher or lower. This paper deals with changes in the susceptibility of spruce wood (Picea abies L. Karst.) to attack by the dry rot fungus Serpula lacrymans, in such situations, when the wood samples 8.5x8.5x120 mm3 (RxTxL) were first pre-treated with 1% water solutions of selected acids (H2SO4, CH3COOH), bases (NaOH, NH4OH) or oxidizing agent (H2O2), or they were also exposed to a higher temperature (190°C/3h). The activity of S. lacrymans was totally restricted only in one situation, if the wood was pre-treated with sulphuric acid and then exposed to 190°C. On the other hand, specimens pre-treated with ammonium hydroxide were more susceptible to bio-attack (in both situations: without or with high temperature pre-treatment effect) than sound ones.
The effects of density on vertical variation of permeability of Sitka spruce within tree
2000 - IRG/WP 00-40156
Tree improvement of Sitka spruce is a combination of silviculture and tree breeding aimed at producing higher quality products including increased growth rate and timber yield, and wood density. It is useful to know annual ring structure and density distribution when studying the quality of wood, grading it, or determining how the wood structure affects residual flow in softwoods. Since density is a factor under genetic control, the study in this article details the effects of density on longitudinal and radial permeability of Sitka spruce from base to apex. Comparison of overall means of both longitudinal and radial void volume filled (%) suggest that longitudinal permeabilities were almost the mirror image of those for the radial permeability along the tree trunk.
Implications for comparability of laboratory experiments revealed in studies on the variability in survival and wood consumption between colonies of Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae
1983 - IRG/WP 1196
(Summary of paper 1193) Groups of Coptotermes acinaciformis, originating from six colonies, three taken from each of two localities, 1500 km apart, in northern Australia (Townsville, Darwin) were kept at population densities of 0.005, 0.01 and 0.02 g termites/mL. Survival and wood consumption of the groups after 8 weeks followed a similar pattern in the colonies from both collection areas. Groups were least vigorous at the lowest population density; their performance reached a maximum at a population density of 0.01 g/mL. The subsequent decline in vigour was less marked as the highest population density was approached. However, the actual values for survival and wood consumption varied widely between colonies, irrespective of their origin. It is recommended that in all laboratory experiments which use survival and wood consumption as indicators of termite vigour, controls of a favourable as well as an unfavourable food type are included which would serve to monitor the vigour of the termites. Results from termite sources whose vigour falls below a certain threshold value would have to be treated with caution and could not be used in definative data, as e.g. in defining critical retentions of wood preservatives.
A standardised procedure for the treatment of timber with test chemicals
1986 - IRG/WP 2257
A procedure is described which allows the standardisation of sample handling and data manipulation during trials invastigating the treatability of timber with test chemicals. The use of computer software allows the data to be handled efficiently.
J Norton, A Zosars, L E Leightley
Natural resistance of twenty-six Guianese wood species against marine borers
1988 - IRG/WP 4144
This note is a contribution on the study of the natural resistance of some wood species from French Guiana, some of which could be found too in the neighbourhood. Here are presented the results after one year exposure in the marine environment.
L N Trong
Absorption of inorganic salts solutions. Retentions of inorganic salts. Fire retardants
1990 - IRG/WP 3625
The study aims evaluated the impregnation capacity using fire retardants on woods with differents densities. At the same time, impregnation with several fire retardant salts were carried out in order to obtain their absortion and retention in wood.
A Garcia, J Navarro
The Pilodyn instrument as a non-destructive tester of the shock resistance of wood
1978 - IRG/WP 2107
A new non-destructive shock resistance tester, the PILODYN, has been developed. The instrument measures the fracture surface area created by a constant amount of energy. It operates by shooting a blunt pin into wood by an exact amount of energy. The penetration depth is read on a scale. A wide field of application is open to a non-destructive shock resistance tester such as: 1) assessment of the residual strength of poles decaying from the outside; 2) laboratory evaluation of biodeteriorated wood; 3) the state of wood foundations and woody pilework; 4) degree of chemical decomposition of wood; 5) degree of thermal decomposition of wood; 6) measurement of the density (strength) of standing trees; 7) measurement of the density (strength) of sawn timber; 8) production control of wood based panel boards. A review of existing test results as well as new results are presented containing items 1, 6 and 7. An evaluation of the potential of the PILODYN is attempted.
Decay resistance of high performance biocomposites based on chemically modified fibres
1998 - IRG/WP 98-40120
Different partners within the framework of a European research project produced high performance biocomposites aiming at the utilisation of board materials as durable products both in dimensional and biological degrading circumstances. This paper summarises test data, which indicate the potential of board materials produced with modified fibre material. The chemical modifications applied cover a range of technologies, which were selected for scaling up experiments. Acetylation, as well as alternative methods like maleiation, phthalylation, succinylation, oxidation and silylation were investigated. Fibre source, density variation and the use of several types of glues were parameters of the total set-up. Basidiomycete testing was carried out using specific methodology for board materials elaborated in CEN standardisation committees.
V Rijckaert, J Van Acker, M Stevens
New developments in wood preservation
1974 - IRG/WP 335
Most of the developments in wood preservation in recent years have been stimulated by changing circumstances, particularly the increasing interest in reducing hazards and environmental, pollution but also the serious difficulties that are now being encountered in obtaining economic supplies of established preservatives. There is perhaps a danger that new controls to reduce pollution dangers may be too severe.
B A Richardson
Some relationship between physical characteristics and treatability of Bolivian woods
1987 - IRG/WP 3434
Using the available data on physical characteristics of 25 Bolivian woods, some relationships between porosity, specific gravity and treatability (hot and cold open tank process with 5% pentachlorophenol) were analysed. The aim of this report is to give information on technical characteristics of Bolivian hardwoods which have been studied in this country by Centro de Desarrollo Forestal and in Peru by Junta del Acuerdo de Cartagena.
A S Viscarra
Ancillary properties of vapor boron-treated composites
2001 - IRG/WP 01-40210
This paper discusses the water absorption, thickness swelling, and internal bond strength of North American composites treated using a vapor boron treatment process. For oriented strandboard, high boron loadings led to lower internal bond strength and lower thickness swelling. Water absorption results were variable but no deleterious effect of treatment was noted. For medium density fiberboard, the highest loadings led to reduced internal bond strength. Thickness swelling decreased with increasing boron level, but not significantly. As with OSB, water absorption results varied.
W A Jones, H M Barnes, R J Murphy
A summary of tests and practical experiences with the Pilodyn wood testing instrument
1980 - IRG/WP 282
This paper presents a summary of the reports, tests and practical experiences with the Pilodyn wood tester not only, however, concerning poles but also in other fields such as standing trees, sawn timber etc. The principle of the Pilodyn is a spring-loaded pin which is fired into the object and the depth to which the pin penetrates is correlated to physical and mechanical properties of the object.
Preservative treatment of Pinus elliottii
1987 - IRG/WP 3435
The treatment of Pinus elliottii with copper-chrome-arsenic preservative by four alternative seasoning and treatment methods is investigated. Steam conditioning followed by either alternating pressure method (APM) or 'Q' treatment resulted in inadequate preservative penetration. Air drying or high temperature drying followed by the Bethell process resulted in a high standard of treatment.
P Vinden, L Carter
Effects of the addition of polyethylene glycol to the CCA-C preservative treatment
1985 - IRG/WP 3337
A modification of the CCA-C wood preservative system for utility poles has been investigated to see if spur penetration into the poles is assisted during climbing. Addition of polyethylene glycol to the CCA system has been shown to accomplish this purpose. This paper addresses the effects of the addition of polyethylene glycol to other physical properties germane to utility poles.
W P Trumble, E E Messina
Methods for testing fumigant efficacies against termites
1986 - IRG/WP 1297
Methodologies for testing fumigants against termites are reviewed and factors needed to be taken under consideration for standardization listed. Toxicity should be defined by both direct exposure to the gas and under more practical "barrier" conditions which include test enclosures simulating abiotic surroundings of the termites, i.e. wood, nest material, etc. To observe latent effects, mortality should be recorded periodically after exposure until rates decrease to control levels. Fumigant efficacy should be reported as a function of concentration and exposure time, termed lethal accumulated dose (LAD).
N-Y Su, R H Scheffrahn
Exterior wood stains
1980 - IRG/WP 3135
Experience has shown that conventional paints cannot now be relied upon to provide a complete seal against water entry, that in practice water can often circumvent the film and that the paint, far from serving to keep water out will seal it in. Moreover present-day paints are often subject to localised and premature failure out of doors and consequently entail high maintenance costs. Problems of wood decay and premature paint failure reached a high level during the 1960s, and led to the acceptance of the need for the preservative treatment of softwood joinery and cladding. The question remains however, whether, in the light of changes in the quality of timber and how it is used, the traditional approach of attempting to seal the outer surface of the wood is still valid, or should be abandoned in favour of using different types of finish which are more permeable to moisture and prevent it accumulating in the timber. One of the reasons for the remarkable success of semi-transparent exterior wood stains is that they met the demand for finishes of increased water vapour permeability for timber which was susceptible to decay. They also possessed two other important attractions: they provided natural finishes for exterior timber which were without the technical problems of clear varnish; and their mode of breakdown by erosion reduced the preparation work in maintenance and hence the overall maintenance costs. These are valid commendations for stains and remain important factors encouraging their use. Stains offer the architect additional design freedom and, used effectively, can make a pleasing contribution to the appearance of modern buildings. They do reduce average moisture levels in the timber and are simple to maintain, though these advantages may be offset to some extent if more frequent maintenance is necessary and if the higher permeability creates problems from dimensional movement.
E R Miller