scholarly journals Influence of natural surface ageing on bonding quality of thermally modified oak and beech wood

2019 ◽  
Vol 70 (3) ◽  
pp. 273-278
Author(s):  
Vjekoslav Živković ◽  
Gustav Gabrek ◽  
Goran Mihulja
Keyword(s):  
Contact Angle ◽  
Shear Strength ◽  
Wood Species ◽  
Contact Angles ◽  
Bonding Quality ◽  
Natural Surface ◽  
Lamination Process ◽  
Thermally Modified Wood ◽  
Modified Wood

This paper presents the influence of natural surface ageing in indoor conditions on bonding quality of thermally modified wood used in structural laminated products. Two unmodified and thermally modified wood species were used for the experiment: oak and beech. Samples were planed and glued with MUF adhesive 2 hours, 1, 2, 6, 10, and 18 days after planing. Properties of laminated beech and oak beams, namely shear strength, delamination and contact angle, were measured in order to detect 1) suitability of wood species for lamination process and 2) influence of extended storage time after planing on properties of laminated wood. Generally, both native and thermally modified beech exhibited better results of shear strength and delamination and had lower contact angles compared to oak and thermally modified oak. Results of the delamination test (total delamination) indicate time dependence of surface ageing. Both unmodified and thermally modified beech may be successfully laminated at least up to 2 days after planing, whereas neither oak nor thermally modified oak are suitable for lamination process due to excessive delamination. Results of delamination may be related to contact angle measurements. Shear strength of glue lines did not show any influence on natural surface ageing. However, whereas beech and thermally modified beech samples exhibited almost the same values of the shear strength regardless of the duration of surface ageing, there is an obvious difference in shear strength of oak and thermally modified oak samples.

scholarly journals Welding of thermally modified wood and thermal modification of the welded wood: Effects on the shear strength under climatic conditions

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3224-3234
Author(s):  
Mojgan Vaziri ◽  
Dick Sandberg
Keyword(s):  
Shear Strength ◽  
Welded Joints ◽  
Negative Influence ◽  
Climatic Conditions ◽  
Thermal Modification ◽  
Modes Of Failure ◽  
Computed Tomography Scanning ◽  
Thermally Modified Wood ◽  
Welding Pressure ◽  
Modified Wood

This work investigated how thermal modification affects the shear strength of welded joints under different climatic conditions. The order of the thermal modification, before or after the welding, was investigated for its effect on the shear strength of the welded wood. Two groups of thermally modified specimens were prepared in a laboratory kiln under controlled conditions, one thermally modified before welding and the other after welding of the specimens. The shear strength of the specimens were measured at four different moisture contents of 10%, 12%, 16%, and 18%, and the results for the two different approaches were compared. Moreover, observations of the X-ray computed tomography scanning and digital microscopy were used to study the density profile and the structural details of the welded joints. The results showed that thermal treatment of the wood either before or after welding had a negative influence on the shear strength, and the modes of failure of the joints in mechanical tests were in most cases brittle. In the weld interface of the wood modified before welding, a rigid material similar to charcoal was produced as a result of the further degradation of wood by welding pressure and frictional motion. Welding of wood before thermal modification, however, yielded thicker and more densified joints with less susceptibility to higher moisture variations than the joints obtained by welding the thermally modified wood.

scholarly journals Comparative analysis of inactivated wood surfaces

Holzforschung ◽  
2004 ◽  
Vol 58 (1) ◽  
pp. 22-31 ◽  
Author(s):  
M. Šernek ◽  
F. A. Kamke ◽  
W. G. Glasser
Keyword(s):  
Contact Angle ◽  
High Temperature ◽  
Wood Species ◽  
Sessile Drop ◽  
Surface Composition ◽  
Contact Angles ◽  
Southern Pine ◽  
Hydrogen Atoms ◽  
Yellow Poplar ◽  
Wood Surfaces

Abstract The surface inactivation of two wood species, yellow poplar (Liriodendron tulipifera) and southern pine (Pinus taeda), was studied following high temperature drying. Surface analysis involved X-ray photoelectron spectroscopy, sessile drop wettability and fracture mechanics of the adhesively-jointed surfaces. The results showed that wood drying at high temperature (i.e., >160 to 180 °C) caused modifications in surface composition. The oxygen to carbon ratio (O/C) decreased and the ratio of carbon atoms bonded to other carbon or to hydrogen atoms vis-à-vis carbons bonded to oxygen atoms (i.e., the C1/C2 ratio) increased with drying temperature. In addition, the contact angle increased with the temperature of exposure, but decreased with time. A dependence on wood species was evident: southern pine surfaces always exhibited higher contact angles than yellow poplar. Also, the rate of contact angle decline with time, dθ/dt, was found to vary with surface composition: this rate corresponded to O/C ratio-changes, especially in the case of southern pine. Southern pine was most susceptible to inactivation particularly when bonded with PF adhesive. Yellow poplar surfaces did not show significant inactivation when exposed to drying temperatures below ca. 180 °C. The results are explained by a relative enrichment of wood surfaces with non-polar substances, hydrophobic extractives and volatile organic compounds that 'become visually evident during the drying process at temperatures above ca. 160 °C. Little change was observed if drying temperatures remained below 150 °C.

scholarly journals Measurement of the degree of polarisation of thermally modified Scots pine using a Stokes imaging polarimeter

2020 ◽  
Vol 27 (2) ◽  
pp. 178-182
Author(s):  
Ilpo Niskanen ◽  
Jukka Räty ◽  
Hariyadi Soetedjo ◽  
Kenichi Hibino ◽  
Hiroshi Oohashi ◽  
...  
Keyword(s):  
Scots Pine ◽  
Treatment Time ◽  
Wood Products ◽  
Maximum Temperature ◽  
Reflected Light ◽  
Heat Treated ◽  
Polarised Light ◽  
Thermally Modified Wood ◽  
Modified Wood

AbstractThis study measured the polarised light reflected from the surface of thermally modified Scots pine (Pinus sylvestris L.) wood using a Stokes imaging polarimeter. The data were analysed using the Mueller matrix method. The Scots pine boards were heat treated in an oven at temperatures of 160 ºC, 200 ºC and 220 ºC, with a heat treatment time of 3 h at the maximum temperature. The results indicated that the chemical composition of the thermally modified wood underwent a permanent transformation, leading to a change in the degree of polarisation of the reflected light. The presented method provides useful information for inspecting the quality of thermally modified wood products.

scholarly journals Physical properties and bonding quality of laminated veneer lumber produced with veneers peeled from small-diameter rubberwood logs

2019 ◽  
Vol 6 (12) ◽  
pp. 191763 ◽  
Author(s):  
P. S. Khoo ◽  
K. L. Chin ◽  
P. S. H'ng ◽  
E. S. Bakar ◽  
C. L. Lee ◽  
...  
Keyword(s):  
Phenol Formaldehyde ◽  
Small Diameter ◽  
Lower Grade ◽  
Bonding Quality ◽  
Laminated Veneer Lumber ◽  
Short Rotation ◽  
Different Temperatures ◽  
Lamination Process ◽  
Lathe Check

The peeling of small-diameter rubberwood logs from the current short-rotation practices undoubtedly will produce lower grade veneers compared to the veneers from conventional planting rotation. Hence, this raises the question of the properties of the produced laminated veneer lumber (LVL) from veneers peeled from small-diameter rubberwood logs using the spindleless lathe technology. Different thicknesses of rubberwood veneers was peeled from rubberwood logs with diameter less than 20 cm using a spindleless lathe. Three-layer LVLs were prepared using phenol formaldehyde (PF) adhesive and hot pressed at different temperatures. During the peeling of veneer, lathe checks as deep as 30–60% of the veneer thickness are formed. Owing to deeper lathe check on 3 mm rubberwood veneer, higher pressing temperature significantly increased the gluebond shear strength of the PF-bonded LVL. In addition, lathe check frequency was also shown to influence the bond strength. The presence of higher lathe check frequency on 2 mm veneer increased the wettability, thus facilitating optimum penetration of adhesive for stronger bonding. These findings stress the importance of measuring and considering the lathe check depth and frequency during the lamination process to get a better understanding of bonding quality in veneer-based products.

scholarly journals The Influence of the Roll-Laminating Process on the Bonding Quality of Polymer-Coated Steel Interface

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 472
Author(s):  
Jiyang Liu ◽  
Qingdong Zhang ◽  
Boyang Zhang ◽  
Mingyang Yu
Keyword(s):  
Bonding Strength ◽  
Coated Steel ◽  
Interface Bonding ◽  
Relevant Research ◽  
Bonding Quality ◽  
Bonding Area ◽  
New Type ◽  
Lamination Process ◽  
Bonding Rate

Polymer-coated steel (PCS) is a new type of metal packaging material under development, which has better performance in saving resources, energy, and environmental protection. The lamination process has an important influence on the bonding quality of the PCS interface. PCS samples under different lamination temperatures and lamination speeds were prepared through experiments. A binding rate is defined to represent the real bonding area of the PCS interface. The micro-scratch tester and scanner are used to study the influence of the lamination process on the bonding rate and bonding strength of the PCS interface. It is proposed that the bonding rate and bonding strength of the PCS interface increases with the increase of lamination temperature and increases with the decrease of lamination speed. The PCS interface bonding rate and bonding strength are positively correlated. SEM and DSC experiments revealed the cause of bubbles on the PCS surface. It is proposed that controlling the uniformity of the TFS surface temperature can reduce the quality defects of PCS surface bubbles. Relevant research results bring guiding significance for the formation of enterprises.

scholarly journals Properties of some thermally modified wood species

2013 ◽  
Vol 43 ◽  
pp. 348-355 ◽  
Author(s):  
Balkis Fatomer A. Bakar ◽  
Salim Hiziroglu ◽  
Paridah Md Tahir
Keyword(s):  
Wood Species ◽  
Thermally Modified Wood ◽  
Modified Wood

scholarly journals Bonding quality of two lesser-used wood species Brachystegia spiciformis and Julbernardia globiflora from Mozambique

2021 ◽  
Vol 23 ◽  
Author(s):  
Narciso F Bila ◽  
Rosilani Trianoski ◽  
Setsuo Iwakiri ◽  
Andrade F. Egas ◽  
Alberto A. Manhiça ◽  
...  
Keyword(s):  
Wood Species ◽  
Bonding Quality ◽  
Brachystegia Spiciformis

scholarly journals PAPER STRAWS: AN INVESTIGATION INTO SURFACE MODIFICATION AND HYDROPHOBIZATION OF CELLULOSE

2020 ◽  
pp. 1-10
Author(s):  
Norbert Banyi ◽  
Jordan Hassett
Keyword(s):  
Contact Angle ◽  
Surface Modification ◽  
Water Droplet ◽  
Contact Angles ◽  
Water Droplets ◽  
Treatment Groups ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Silylation Reaction

In order to improve the quality of paper straws, experiments involving the hydrophobization of paper, in a silylation reaction with chloro(dimethyl)octadecylsilane using various solvents, were conducted. The ImageJ program was used to quantify hydrophobicity by calculating the contact angle between a water droplet and a small piece of paper, which were compared between treatment groups as well as with untreated paper and plastic straws. Samples were exposed to a variety of liquids in one-hour periods for a total of six hours. After each hour, contact angle measurements were taken. Results suggested that hydrophobicity declines with time due to leaching of silanol from the treated paper. Contact angles between water droplets and the treated paper remained larger than that of untreated paper straws throughout testing, indicating higher hydrophobicity. Furthermore, samples that were silylated using dioxane as a solvent were better able to maintain hydrophobicity than samples silylated using toluene as a solvent.

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