WOOD RESEARCH Volume 69, Number 4, 2024
JINGE XIE, HONGHAI LIU, YU XIE, and XIAOKAI ZHANG

INFLUENCE OF TEMPERATURE AND PRESSURE ON SUPERCRITICAL CO2 DEWATERING OF BAMBOO STRIPS

In this study, therepressure (15, 22.5, 30 MPa) and two temperature (45, 60°C) of ScCO2dewatering were tested on Moso bamboo (Phyllostachys edulis) strips. The aim was to research the effects of these conditions on the dewatering rate, moisture distribution, and shrinkage of bamboo. The results showed that: 1)The first cycle discharges the most water of all drying conditions. The most effective dewatering time consisted of a 15 min depressurization period and a 5 min discharge period. 2)The ScCO2 dewatering rate of bamboo strips decreased with decreasing MC, with a maximum decrease of 78%.The maximum and minimum dewatering rates were 37.04%/h and 4.41%/h, respectively. The dewatering rate was synergistically affected by temperature and pressure, which increased significantly with pressure at 45°C, but was minimized at 60°C at 22.5 MPa. 3)After dewatering, the moisture distribution in the bamboo strips shows a trend of higher moisture content(MC) in the middle and lower MC on both sides in the tangential and radial directions. 4)Most of the bamboo strips produced shrinkage after the 1st cycle of dewatering, and the overall shrinkage in the tangential direction was greater than that in the radial direction. The maximum tangential and radial shrinkage rations are 3.06% (22.5 MPa/45°C) and 0.94% (15 MPa/60°C), respectively.

WOOD RESEARCH Volume 69, Number 1, 2024
YEFRI CHAN, DWI ARIES HIMAWANTO, BUDI KRISTIAWAN, and INDRI YANINGSIH

SHORT NOTE. THERMAL CHARACTERISTICS OF SENGON WOOD DRYING USING INFRARED AND COMBINED INFRARED-HOT AIR METHODS

This research aimed to determine the thermal characteristics of sengon wood due to drying at temperature of 70, 80, and 90oC with air velocity of 1 and 3 m/s using infrared (IR) and combined infrared-hot air (IR-HA) method. The thermal characteristics analyzed included temperature distribution, reduction in moisture content, and drying rate. The results of drying wood samples using IR method showed that the fastest drying time was obtained at 90oC with air velocity of 1 m/s. However, for combined IR-HA method, the optimal condition was achieved at air velocity of 3 m/s. The largest drying rate attained using combined IR-HA method was 0.27 g/min, while the smallest was recorded at 0.094 g/min with IR method. These results showed that combined IR-HA method produced a more evenly distributed temperature and faster drying time compared to the IR method

WOOD RESEARCH Volume 62, Number 3, 2017
Ján Svoreň, Ľubomír Javorek, Mária Krajčovičová, Katarína Klobušiaková, Ivan Kubovský, and Richard Kminiak

The effect of the circular saw blade body structure on the concentric distribution of the temperature along the radius during the wood cutting process

The paper presents the experimental results of a research aimed at the distribution of the temperature on thecircular saw blade body. The temperature was measured at four distances from the centre of the circular saw blade body (60 mm, 70 mm, 80 mm, 90 mm) by means of an infrared thermometer. Three circular saw blades with the diameter of 350 mm and a variable adjustment of the body (without slots and coating, with slots and without the coating, with both slots and coating) were used for the longitudinal sawing of the spruce wood (Picea excelsa) with the thickness of h = 25 mm. Feed speed vf = 12 m•min-1 and cutting revolutions n = 4000 min-1 were constant. The measured temperature was in the range from 22°C to 30°C. The highest measured temperatures were recorded on the circular saw blade with the slots and coating.

WOOD RESEARCH Volume 63, Number 5, 2018
Hamza Cinar

Effects of temperature and thickness of wood based boards on formaldehyde emission

This study investigated the effects of board thicknesses and temperature on formaldehyde emission (FE) for different wood based boards, sampled from standard particleboard (PB) and medium density fiberboard (MDF). Test samples with the thicknesses of 8, 12, and 18 mm analyzed for formaldehyde emission at temperatures of 10, 20, 25, and 30°C and 65% relative moisture conent for 60, 120, and 180 minutes after production. The highest value of FE was found at 1.2922 ppm for PB and 0.3800 ppm for MDF of 18 mm, treated at the temperature of 30°C. The lowest emission was found to be 0.0611 ppm in the PB of 8 mm, and 0.0444 ppm for 18 mm MDF, treated at a temperature of 10°C. A significant increase for FE was detected in all board types at the temperatures of 20, 25, and 30°C. However, a significant decrease was also detected at 10°C for all types of boards. Accordingly, an increase from 101% to 1,192% and a decrease from 39% to 9% was observed for PBs. MDF samples yielded better results as an increase from 4% to 280% and a decrease from 55% to 31%. Regarding distance to E1 (0.10 ppm), all values were above the limits of E1 (≤ 0.10 ppm, EN 717-1), except samples treated at 10°C. In conclusion, the temperature and thickness of wood based boards significantly affect their formaldehyde emissions.

WOOD RESEARCH Volume 64, Number 6, 2019
Huajun Dong, Qifan Wang, Jun Shen, and Bin Zeng

Effects of temperature on volatile organic compounds and odor emissions of polyvinyl chloride laminated MDF

The objective of this study was to investigate odor active compounds of polyvinyl chloride (PVC) laminated medium density fiberboard (MDF) and explore the effect of temperature on total volatile organic compound (TVOC) and odor emissions. A micro thermal extractor was used based on the technology of gas chromatography–mass spectroscopy/olfactometry. The results showed that fruity, sweet, fragrant, and aromatic were the dominant odor impressions of PVC laminated MDF and were primarily concentrated in aromatics. Decoration treatment could effectively prevent the release of some odor compounds from MDF, yet these could add new odor substances. In the test period, the total odor intensity of MDF decreased more rapidly than that of PVC because of the characteristic of exposure. The TVOC from PVC increased when the temperature increased, and the effect was more significant early in the test period. Increasing temperature could accelerate the appearance of some odor active substances. The fastest release of odorant compounds occurred at 40°C. At higher temperature (60°C in this experiment), some substances could be enhanced, causing an increase in TVOC and odor. The temperature contrast between 40°C and 60°C contributed greatly to the release of alkanes, alcohols, esters, and ketones.

WOOD RESEARCH Volume 65, Number 6, 2020
Roman Fojtík, Lenka Kubíncová, Viktor Dubovský, and Kateřina Kozlová

Moisture at contacts of timber-concrete element

The subject of the article is to monitor the changes of moisture on the contact surface concrete and timber part of the composite timber-concrete beam. The moisture directly affects the properties of timber and causes its volume changes and degradation processes. These effects reduce of durability and load capacity of the structures. The beam was placed at the exterior. The observed contacts of the beam are often critical on real structures, as it is difficult to repair and maintenance in the case of increasing moisture or intrusion of dirt. The experiment was used to monitor and evaluate the dependence of changing moisture in contacts depending on ambient environmental conditions.