WOOD RESEARCH Volume 69, Number 3, 2024
HILAL ULAŞAN and CEVDET SÖĞÜTLÜ

THE EFFECT OF SUPPORT LAYER MATERIAL AND ADHESIVE TYPE ON COMPRESSIVE DYNAMIC BENDING AND SHEAR STRENGTH IN LAMINATED WOOD

In this study, strength properties of wood material reinforced with carbon fiber fabric, steel wire mesh and bamboo veneer were determined. Polyvinylacetate (PVAc) and polyurethane (PUR) glues (D4)were used for the lamellas obtained from Scotch pine (Pinus sylvestris L.) and eastern beech (Fagus orientalis L.). Compressive strength according to TS EN 408+A1; dynamic bending (shock) strength according toTS ISO 13061-10 and shear strength according to ASTM D 3110 were determined on 3 and 5-layers samples. According to the results, the highest compressive strength (62.8 N/mm2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue. The highest dynamic bending strength value (110.8 kJ/m2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue and the highest shear strength value (12.3 N/mm2) in 3-layered eastern beech samples reinforced with steel wire mesh and bonded with PUR glue

WOOD RESEARCH Volume 61, Number 5, 2016
Adam Krajewski, Paweł Kozakiewicz, and Piotr Witomski

Shear strength of Scots pine (Pinus sylvestris L.) from the historical buildings

Comparative research was conducted on shear strength parallel to grain of heartwood of Scots pine (Pinus sylvestris L.) from the 16-18th century from Central Poland and of modern wood. Tests were performed on 150 samples of aged wood from 13 construction elements of 4 historic buildings and on 100 samples from 10 modern constructional elements. Aged wood revealed a better technical quality. The difference of average shear strength parallel to grain values equaled 0.09 MPa and the translation of correlation line was about 0.35 MPa in favour of aged wood.

WOOD RESEARCH Volume 61, Number 2, 2016
Cosmin Spirchez, Aurel Lunguleasa, and Tatiana Griu (Dobrev)

Testing model for assessment of lignocellulose-based pellets

This paper aims to find a simple testing and assessment model applicable to lignocellulose-based pellets, for the purpose of making the appropriate selection from the market. It is analysed the main tests of pellets, as density, caloric value and shear strength, for three different types of pellets bought from the competitive market. Afterwards is detailed the method of operation for the shear strength due to its not so frequent use. Finally, based on the tested values and limits required by the existing standards, it is determined a simple method for assessing for pellets, pointing out the closeness of each tested value to the standard limits.

WOOD RESEARCH Volume 62, Number 5, 2017
Igor Čunderlík, Peter Vilkovsky, and Vladimír Račko

Shear strength and analysis of shear area on wood/bark interface on beech wood (Fagus sylvatica L.)

The structure of both cambium and the last-differentiated cells from cambium influence the adhesion of bark on wood. In the submitted paper, the bark/wood adhesion is evaluated by means of measuring the shear strength in longitudinal and tangential direction of the wood/bark interface on woody plant beech (Fagus sylvatica L.) during one year. The growing period and dormant period and moisture of the wood/bark interface proved to be important factors influencing the shear strength. The shear strength measured during the dormant period in the greenstate showed values approximately 100% higher than those measured during the growing period. Considering the 12%-moisture, the values of shear strength proved to be circa 300% higher in comparison to the green state. The shear area during the dormant period was led through the zone of the last-created sieve tubes of non-collapsed late phloem, whereas during the growing period the shear area passed through the cambium zone. The structure of shear areas is also significantly influenced by diverse structure of narrow and wide phloem rays.

WOOD RESEARCH Volume 62, Number 5, 2017
Rongrong Li, Wei Xu, Lu Fang, Pingxiang Cao, Xiaolei Guo, and Mats Ekevad

Short Note: Non-standard test method for glue line shear strength

The relevant standards for glueline shear strength testing were summarized and analyzed in this paper. Depending on these existing test standards, the resulting stress in glueline is not pure shear stress, but a combination of shear and normal stresses. In order to overcome this deficiency, a symmetrical structure was proposed for making samples. Some comparative testing was accomplished by using these symmetrical samples, the results showed that the normal stress could be avoided during testing. These results were also confirmed by finite element method (FEM), the simulation results showed that the shear stress in glueline was uniform.

WOOD RESEARCH Volume 63, Number 2, 2018
Lingling Huang, Huiyun Wang, Xiaolei Guo, Zhihua Jiang, Feng Xing, and Mats Ekevad

Study on continuous cold-pressing technology of engineered wood flooring with EPI adhesive

The effects of process parameters (adhesive spread, press time, and applied pressure) on the gluing performance of engineered wood flooring bonded with emulsion-polymer-isocyanate (EPI) adhesive were studied. The results showed (shear strength and aging test) that the major factors were adhesive spread and press time. The optimized parameters for best gluing performance of engineered wood flooring were 160 g. m-2, 14 s, and 60 s for adhesive spread, heat time, and press time, respectively, within certain ranges.

WOOD RESEARCH Volume 64, Number 5, 2019
Jun Zhang, Lihong Xiong, Xiaojian Zhou, Guanben Du, Jiangkun Liang, and Xuedong Xi

Development of mimosa tannin-based adhesive cross-linked by furfuryl alcohol-formaldehyde and epoxy resins

A furfuryl alcohol-formaldehyde resin was synthesized as a crosslinker in our laboratory to develop a mimosa tannin-based adhesive with good water resistance. 13C nuclear magnetic resonance and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy indicated that furfuryl alcohol reacted with formaldehyde under acidic conditions and that–CH (–OH) – groups to be the ones involved in the crosslinking of mimosa tannin-furfuryl alcoholformaldehyde adhesive (TFF). The wet shear strength of TFF-bonded plywood suggested that the cured TFF adhesive was better than mimosa tannin-furfuryl alcohol (TF) adhesive. The water resistance of TFF adhesive cross-linked with 9% epoxy resin was also higher than those of TFF and TF adhesives.