Showing papers in "China Wood Industry in 2002"

Preliminary Study on Microwave Modified Wood

Abstract: Canada Poplar (Populus canadensis) and Manchurian Ash (Fraxinus mandshurica) wood were modified by microwave heating for various treating times. They were then dried together with similar untreated wood under the same drying conditions. Experimental results were based on electron microscope scans as well as data collected on drying speed and shrinkage measurements from modified and unmodified wood. The results showed, 1) some pit membranes of the treated wood were destroyed and some tylose were redistributed, or separated out after the microwave modification process, 2) the modified wood revealed better properties than the unmodified wood, especially the hardwood. The treated wood was found to have lower density, a larger shrinkage ratio, a higher water absorbing characteristic and a faster drying speed.

Liquefaction of Wood and Its Applications in Polymer Materials

Abstract: Wood, as a solid natural polymer material, could be liquefied into solution reactive molecules which could be further developed into novel polymer materials such as adhesives, moldings, foams and fibers. These facts imply that completely new fields of utilization of wood have been opened. The advances of wood liquefaction in the past twenty years, involving the methods, mechanism and applications of the products, were reviewed in the paper.

The Effects of Wood Extraction on Mammal Growth

Abstract: The 4 common wood species, Pinus koraiensis, Abies nephrolepis, Fraxinus mandshurica and Betula platyphylla , growing in north part of China were selected and effects of the wood extraction component on mammal growth were analysed. Results indicated that some extraction from Pinus koraiensis and Betula platyphylla wood can play a medicine and health protection role. They have good regulating function to mammal growth.

Creep Behavior and Bending Properties of Poplar LVL in Different Assembly Types

Abstract: The effects of compression ratio, assembly type and reinforcement method on mechanical properties of Poplar laminated veneer lumber (LVL) were investigated Among all the factors, the compression ratio was the most effective Higher compression ratio resulted in higher modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength but less deflection related to creep LVL assembled using thinner veneer on the face and thicker veneer in the core layers, as well as LVL made by resin impregnated veneer showed better mechanical properties LVL with fiberglass reinforcement had less effective influence The creep behavior of LVL was similar to that of wood However, the instantaneous recovery of LVL specimens, measured after load removal, was less than the instantaneous deflection Some assembly types mentioned in this paper could benefit LVL by increasing MOR and MOE as well as modifying creep behavior

Properties Test on Fire Retardant Plywood

Abstract: Some Lauan( Shorea spp.)and Manchurian Ash( Fraxinus mandshuria ) plywood were treated with fire retardant CU 60 and their properties were also tested. Results showed that the fire retardant property of the treated plywood could reach fire retardant grade B 1;the adherence of paint film grade could reach level 2; the bond strength decreased less than 10% according to the demands of related standards.

Effect of Wood Powder Content on Properties of Wood Powder-Polypropylene Composites

Abstract: This article deals with the mechanical properties of wood powder polypropylene composite panels and the morphology of the esterification of the wood surface while varying the level of wood content. Compared with 100% PP boards, the mechanical property results for the composite boards, except for impact strength, were observably improved with all wood powder contents. On the other hand, the morphology characteristics of the composites showed that the esterification treatment of the wood surface could improve the interfacial adhesion and dispersion between the polypropylene and wood powder. The SEM observation revealed that there were inlay structures in the composites, which meant that there also had been a physical combination between the polypropylene and wood powder.

Quality Control on Wood-based Panel Overlaid with Paper Impregnated Melamine Resin

Abstract: In this article, the author discussed how to control the quality of the overlaid wood based panels with papers impregnated melamine resin during processing. It also analysed the causes of common production problems and some resolving measures.

Current Situation and Development Trend of Wood/Wood Composites Fire-retarding Technology

Abstract: The current status of fireretardant treated wood and wood composites, both domestic and imported, are reviewed in this paper. The types of fireretardant and their characteristics, as well as application, treating technology and testing methods for fireretardant products, are also presented. Finally, the development trends of fireretardant treated wood and wood composites are discussed.

Status of Wood Product Supply and Demand in China

Abstract: This paper reviews the current status of wood product supply and demand in China. It then discusses countermeasures to solve the various problems.

Technology of Acid-deresination for Pinus massoniana Boards

Abstract: A new kind of acidderesination agent was developed to treat Masson's Pine (Pinus massoniana) boards (500 mm×200 mm×55 mm ), a fast growing plantation species. The boards were treated under a low temperature and low wood to solution ratio. Compared with untreated board, the results showed that treated boards retained their original color. However, there was a small decrease in other physical and mechanical properties of boards. The treated wood is suitable as furnishing and furniture materials.

New Technology on Surface Compression of Plantation Softwood

Abstract: The plantation wood of Pinus taeda was compressed on the surface with a new improved treatment technology Results showed that with the increase of modified methane diisocyanate concentration, the increase of weight percent gain ( WPG ) and the decrease of thickness swelling and compressive deformation recovery efficiency were remarkably The modulus of rupture (MOR) and modulus of elasticity (MOE) properties of surface compressive wood were increasedby 439% and 301% compared with the control specimen respectively Surface compressed wood had much improved fire retardant effect, abrasion resistance and surface hardness

Application of Variation Coefficients Maxwell Body to Fit the Creep of MDF

Abstract: It was the multi unit combined spring and damp model that was widely used to study rheological properties of wood material, but its some constant coefficients were not easily solved In this paper, a concept of variation coefficient rheological model was put forward, which adopted two unit Maxwell body of variation coefficients to simulate the creep behavior of medium density fiberboard (MDF) Results showed that the model could be effectively used to fit the creep of the MDF, and easily to seek the rheological coefficients because of its fewer units of combination modulus of spring damper The author also indicated that the model could fit the creep of MDF on changing load with Boltzmann superposition principle

Review of NDE Technology as Applied to Wood Preservation

Abstract: Preserving old trees and ancient wood structures are important areas of wood preservation Non destructive evaluation (NDE) is a new technology being applied to this field This paper investigates the application of NDE technology into the evaluation of the safety of ancient wood structures as well as the determination of the health of old trees in China This paper discusses the major uses, common techniques and types of equipment used when using NDE technology in wood preservation applications

Method of On-line Detecting Wood Surface Defects by Laser

Abstract: This paper presentes an on line method for detecting crack and knot of planed lumber surface. The system is consisted of a laser sensor which provides scanning signal, a FFT analyser which records a curve and a personal computer which analyses and processes data from FFT analyser. The system could not only distinguish crack and knot of wood surface quickly and accurately, but also calculate size of each defect according to the data from record curve.

Properties of Medium Density Fiberboard of Rice-straw with UF Resin

Abstract: The feasibility of medium density fiberboard (MDF) manufactured from rice straw with urea formaldehyde (UF) resin was investigated and the effects of board density, resin consumption and water repellent on properties of the board were also studied. Results showed that the properties of rice straw MDF with UF resin could meet the requirement of GB/T 11718 1999 when the board density was 0.8 g/cm 3 and resin consumption equaled 17%. Thickness swelling of board was improved greatly when water repellent was added at 1.2%.

PF Poplar Flakeboard from Steam-injection-vacuum Pressing

Abstract: Phenol formaldehyde resin (PF) is used widely in water resistant wood based panel manufacturing in China, but its above 100 ℃ curing temperature and long pressing time result in low productivity. This study focused on Poplar flakeboards using aqueous phenol formaldehyde resin (PF) by steam injection vacuum pressing(SIVP) . Comparing the processing parameters and quality indexes of board by SIVP with that in conventional techniques, the results showed that by SIVP, the board pressing time could be shorten to 35% of that in conventional pressing; some physical and mechanical properties of the boards could be improved: the thickness swelling ( TS ) was decreased by 33%, the internal bond strength ( IB ) increased about 15%, formaldehyde emission of the board was reduced by 24%. But the bending property of board was reduced significantly. The board had higher core density with more uniform density profile.