Determining the impact of sensor orientation on moisture content measurements in eastern white pine

As buildings become more airtight and insulated, the movement and accumulation of moisture within building envelopes become paramount in determining its resiliency. Current methods for quantifying the moisture content (MC) of wood species involve the measurement of electrical resistance between two installed electrodes and the use of existing empirical correlations to evaluate the MC. However, these correlations do not adequately consider the impact of sensor orientation within wall assemblies. The objective of this paper is to determine the impact of MC readings within a wood sample due to sensor orientation. A total of 126 eastern white pine samples were tested with electrodes placed along the grain of the wood (longitudinal), across the grain of the wood (tangential), and in a diamond pattern, using six different fasteners as electrodes. The samples were placed in a controlled environmental chamber until steady state was achieved at approximately 18% MC. Electrical resistances of the samples were measured in both directions at temperatures ranging from -10°C to 40°C. It was found that the tangential-to-longitudinal resistance ratio is 1.1-1.35 depending on the electrode type.

In Polymerization of Environment Friendly Melamine-Urea-Glyoxal Resin in Rubber Wood for Improved Physical and Mechanical Properties

In the study, we report that a safe and simple way for upgrading inferior rubber wood through the combined modification of environment-friendly MUG resin was synthesized from glyoxal, melamine, urea, and other additives. MUG-treated wood samples were prepared with six different MUG resin concentrations (5, 15, 25, 35, 45, and 55 wt %) into the wood matrix and then heated and polymerized to form a solid and hydrophobic MUG resin in the wood scaffold, and the physico-mechanical properties were evaluated. As the MUG resin concentration increased, the weight percent gain and density increased, water uptake and leachability decreased, and the antiswelling efficiency increased at first and then decreased. MUG-treated wood sample can be prepared when the MUG resin concentration was set as 25%, and the physical properties of treated wood was optimum. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis showed that the MUG resin is widely distributed in the cell lumens and cell walls. With enhanced physico-mechanical properties, MUG-treated wood sample can be well used as a promising alternative to existing engineered wood products for structural applications.

Thermal conductivity of untreated and chemically treated poplar bark and wood

The thermal insulation properties of bark and wood of a poplar tree (Populus nigra × alba) were investigated using a guarded hot plate device (GHP) and a purpose-built miniature heat flow meter (Mini-HFM). To reduce their density and improve their performance as insulation material, bark and wood were chemically treated. The correlation between thermal conductivity and test temperature as well as between thermal conductivity and material moisture was investigated. By means of the treatment 44 and 34% of the mass of bark and wood, respectively, was removed and the equilibrium moisture content of the both materials decreased significantly. For untreated bark, a thermal conductivity of 0.071 Wm−1 K−1 and 0.140 Wm−1 K−1, respectively, were determined in transverse and axial direction. For wood, measurements showed comparably higher conductivities of 0.078 Wm−1 K−1 and 0.204 Wm−1 K−1 in transverse and axial direction. By reducing density, thermal conductivity of bark decreased up to 24%, whereas for wood reductions between 10 and 35% were found. It was shown that the self-constructed Mini-HFM is a useful and reliable instrument to determine the thermal conductivity on a small wood sample in the three main anatomical directions.

A Facile Preparation of Environmentally-Benign and Flame-Retardant Coating on Wood by Comprising Polysilicate and Boric Acid

For the sake of direct using on the built wooden buildings, a green flame resistance coating comprising sodium polysilicate (SPS) and boric acid was prepared. With weight gain of only 10 wt.%, the treated wood sample (SPS/B-wood) performed improved limiting oxygen index value of 40.3% and passed the V-0 rating in UL-94 test. Additionally, the total heat release, total smoke production and peak carbon monoxide production of SPS/B-wood sample were decreased by 24.5%, 36.0% and 59.4% respectively, compared with that of control wood sample. The residue of SPS/B-wood sample was increased to 54.0% from 18.4% of control wood sample at 800oC in the thermogravimetry analysis. The flame retardant mechanism was suggested that SPS and boric acid formed Si-O-B and Si-O-Si contained structures, isolating the heat and smoke transfer during wood combustion. Notably, NaOH, introduced by the SPS/B coating, catalyzed the lignin to form compact and high-quality char. To conclude, this low-cost and easily-operated coating has a promising future utilizing in the villages with dense wood buildings.

Installation of Test Setup and Measurement Procedures in Fir Wood Hydraulic Conductance Measurement

For a hydraulic conductor, through which liquid flows, hydraulic conductance (K, ml·s-1·MPa-1) is defined as the ratio of pressure difference at the inlet and outlet to the fluid amount passing through the hydraulic conductor in a unit time period. This property is one of the key functions of the wood, and is obtained by the flow rate (F – Flow, ml·s-1) along the wood sample divided by the pressure difference driving the flow (DP, MPa). This study aimed to establish a test setup to determine the hydraulic conductance values of Uludağ Fir (Abies bornmulleriana Mattf.). A test setup was established to measure the amount of water that flows in samples and pressure difference in characterized capillary tubes. In addition, calibration of the test apparatus is explained in detail. Fir wood samples taken from Yedigoller, which is affiliated to Kale Operation Chieftainship and Bolu Forest Regional Directorate, of 4 mm in diameter and 3 cm in length were prepared and hydraulic conductance measurements were performed, and the results are presented in this article. The installed test setup was used to obtain the following information about trees: operation of the hydraulic conduction system, the amount of needed water, seasonal effects and stress-related changes.

The Effect of Variables on Laboratory Termite Testing: Part 4—Test Block Species, Size, and Test Photoperiod

The objective of this study was to determine the impact on termite feeding of wood sample size and species and test photoperiod in standard tests. Native species (Reticulitermes flavipes) and introduced species (Coptotermes formosanus) were tested in an American Wood-Preservers' Association E1 standard laboratory test. For testing involving treated wood, southern yellow pine was determined to be preferable to spruce based on its treatability and availability. Test blocks of 25 by 25 by 6 mm were deemed adequate for testing, with large blocks presenting difficulty with retrieval of termites to determine mortality and smaller blocks being consumed too rapidly by the termites in the test. Photoperiod comparisons were not significantly different for R. flavipes; however, C. formosanus indicated a preference for 100 percent darkness. Therefore, the recommendation is to maintain tests using each species in a 100 percent dark environment.

Связь механических свойств анизотропных материалов с их теплофизическими характеристиками на примере древесины сосны

The paper discusses experimentally found relation between mechanical an thermal physical properties of anisotropic materials observed at the pine wood (Pínus sylvéstris L). Hardness and main components of temperature diffusivity tensor measured at the normal to the fibers, tangential and radial faces of the pine wood sample having various moisture content can be linked with linear relations. It renders possible to make express estimation of anisotropic materials mechanical properties typically requiring labor and material extensive destructive testing by means of measurement of its thermal properties using dynamic thermography.

Design of an Acoustic-Based Nondestructive Test (NDT) Instrument to Predict the Modulus of Elasticity of Wood

Modulus of elasticity (E) can predict the mechanical characteristics, as well as grade the quality of wood. The Destructive Test (DT) method is the more commonly used, where the wood sample is split up when being tested. This research used the NDT method based on the longitudinal stress wave method (LSWM) whilst utilizing handheld instruments. The calculated E-dynamic (Ed) from the NDT method was compared with the E-static (Es) from the DT method to validate the technique. Six different wood types were tested with ten samples of each kind. An average R-value of 0.898 was obtained, indicating a high correlation between the Ed values and Es values. The LSWM method requires reliable hardware and software to record the impulse response. It starts by hitting the wood with a hammer to create an impulse, finding the resonance frequency (f0), and later calculating the Ed. A more practical and easy-to-use handheld mobile instrument was developed using a Raspberry Pi-2 microcomputer as the signal processor, an LCD touchscreen, a USB soundcard, and a dynamic microphone that covers 0.1-5kHz and -64 ± 3dB. An internal telecommunication system is provided to support measurements conducted at lumber mills. The software includes band-pass filtering of the recorded spectrum where the f0 is depicted. A time-domain envelope fitting is then applied to the filtered spectrum to obtain the R2envelope. A low R2envelope value indicates an inadequate impulse response, and therefore, the test should be redone.

Enhancement of the physical and mechanical properties of wood using a novel organo-montmorillonite/hyperbranched polyacrylate emulsion

In this work, a novel waterborne hyperbranched polyacrylate (HBPA) dispersed organo-montmorillonite (OMMT) emulsion was synthesized and used for the treatment of wood in a vacuum environment in order to enhance the physical and mechanical properties of the wood. The sapwood of Cathay poplar (Populus cathayana Rehd.) and Radiata pine (Pinus radiata D.Don) were used as the samples for experimentation. The results showed that the physical and mechanical properties of the wood improved significantly due to the successful penetration of the OMMT and HBPA into the wood cell wall. From it was also observed that OMET completely exfoliated from the HBPA matrix and formed a hydrophobic film covering on the inside walls of the cell lumen. Further, it was observed that the poplar sample displayed better mechanical properties than the pine sample because the pine has a more compact structure when compared to poplar and contains rosin. Furthermore, it was also observed that the mechanical properties of the modified wood sample gradually improved with an increase in the concentration of the emulsion. However, excessive concentration (>4 wt%) did not lead to further improvement.