Abstract
This article deals with the effect of alternating lower (freezing) and higher (heating) temperatures on the static bending characteristics of glued Norway spruce (Picea abies (L.) H. Karst.) and European larch (Larix decidua Mill.) wood. Two types of wood, PUR (polyurethane), and EPI (emulsion polymer isocyanate), were used for the experiment. The thermal loading of glued wood was carried out at temperatures −15 °C/70 °C and −25 °C/70 °C. Static bending characteristics were determined on glued wood samples and compared with the reference samples. Freezing causes an increase in the bending properties of both glued spruce and larch wood. The highest in bending strength was obtained for EPI-glued larch wood subjected to −25 °C/70 °C loading temperature, which is by as much as 20% increase from the reference value. The maximum improvement in the modulus of elasticity was achieved for EPI-glued larch with around 11% increase, although the increased values of bending strength and modulus of elasticity were not significant. The different densities, anatomical structures, and properties of spruce and larch wood can induce varying results between the two wood species.
Highlights
Em is the modulus of elasticity (MOE) (MPa); l1 is the distance between the centres of the supports; b is the width of the test sample; t is the thickness of the test sample; F2 –F1 is the increment of load on the straight-line portion of the load-deflection curve (F1 shall be approximately 10% and F2 shall be approximately 40% of the maximum load) (N), and a2 –a1 is the increment of deflection at the mid-length of the test sample
A regression model with a coefficient of determination was used to determine the dependence of bending strength (MOR) and modulus of elasticity (MOE) on thermal loading for spruce and larch wood glued with individual adhesives
It can be deduced that freezing did not cause any significant change either in the density or moisture content of the wood
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The bonding strength of wood structure glued by 1C-PUR is high, and the behavior of the adhesive under load is comparatively ductile [18,19]. Wang et al [28,29,30] reported the tensile shear strength of Scots pinewood and bonded area with different adhesive systems exposed to different temperatures from 20 to −60 ◦ C. Forests 2022, 13, 364 thermal loading has not been studied widely for bending characteristics and different wood species This the impact impactof oftwo twolevels levelsofoffreezing freezing and heating temperatures the bending strength of glued specimens of larch and spruce species bonded with two on the bending strength of glued specimens of larch and spruce species bonded with two differentadhesive adhesivesystems: systems:1C-PUR.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
