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Published By "Faculty Of Forestry, University Of Zagreb"

1847-1153, 0012-6772

2021 ◽  
Vol 72 (4) ◽  
pp. 411-416
Author(s):  
Gülşah Altunışık Bülbül ◽  
Ayhan Gençer

In this study, hand sheets were made from pulp produced by the Kraft method using avocado wood. The raw materials were supplied by a fruit orchard and consisted of avocado (Persea americana Mill.) trees that had completed their useful life and were cut during routine thinning maintenance. In order to determine the ideal cooking conditions in the production of pulp from avocado wood via the Kraft method, 16 cooks were carried out by varying the cooking time (T), active alkali (AA), and sulfidity (S) ratios. The general pulp properties, especially the screened pulp yield, pulp viscosity, and Kappa number, were evaluated. The pulp yield was taken as the primary basis in determining the cooking conditions. The ideal cooking conditions were also determined by considering some physical, mechanical, and optical properties of the paper. According to this study, the conditions found to be ideal in pulp production from avocado (Persea americana Mill.) wood via the Kraft method were: 18 % AA, 22 % S, and 75 min T.


2021 ◽  
Vol 72 (4) ◽  
pp. 337-346
Author(s):  
Rıfat Kurt ◽  
Erol İmren

This study aimed to separate the wood production in regions and provinces of Turkey into homogeneous groups based on similarities by using the country’s wood production figures for 2013 and 2018. Within this context, the hierarchical Ward’s and non-hierarchical K-means clustering methods were used comparatively. Clustering analyses of 2 to 6 in number were performed via both methods, and the same regions mostly fell into the same cluster groups, although in different cluster combinations. The results showed that some provinces with rich forest areas did not produce enough wood. It was observed that these provinces were in the same clusters with provinces having a low amount of forest areas and low wood production. Over the five-year period, very few provinces and regions differed in line with the previous development plans. The creation of a spatial database for wood raw material production using the findings obtained in this study will contribute to the development of operational inventory methods that can be included in long- and medium-term forestry plans.


2021 ◽  
Vol 72 (4) ◽  
pp. 389-401
Author(s):  
Mariana Sedliačiková ◽  
Martina Kánová ◽  
Josef Drábek

The study is focused on behavioural aspects in the financial decision-making process of wood-processing enterprises. The main aim was to map this topic and determine the key behavioural factors that lead management to make mistakes. Primary data on this issue were obtained from an empirical survey. The empirical survey was conducted through a questionnaire that contains questions focused on behavioural decision-making aspects. Using statistical methods, three key behavioural factors were determined. By selecting the given behavioural factors, it was established that love, hate, and sadness are the key factors that influence management behaviour and decision-making. In the real business environment, two managers working in a wood processing enterprise were chosen; they were willing to provide us with a review and opinion on the results of the survey. By analysing all the data, it has been concluded that, even though managers are trying to direct their behaviour and activities, they often do not notice the influence of these factors, and sometimes they are unable to make decisions. The managers should be able to direct their behaviour and activities, to provide self-control and take into consideration the fact that these factors are always present. Results determine the key and systematically occurring errors in the financial decision-making process, caused by the influence of the human factor. We have developed a model for activating the three key behavioural factors applied in the financial decision-making process as a tool that can help company managers not to make the wrong decisions.


2021 ◽  
Vol 72 (4) ◽  
pp. 365-372
Author(s):  
Ismaeil Zahedi Tajrishi ◽  
Asghar Tarmian ◽  
Reza Oladi ◽  
Miha Humar ◽  
Masoud Ahmadzadeh

One strategy for improving the treatability of refractory wood species is biological incising, and its efficiency depends on how the microorganisms modify the porous structure of the wood. Evaluation of the bioincised wood treatability on a micro-scale can thus help to better understand the treatability enhancing mechanisms. In the present study, the biodegradation pattern and micro-scale treatability of Loblolly pine (Pinus taeda L.) heartwood were determined after bioincising with the white-rot fungus Physisporinus vitreus (Pers.: Fr.) P. Karsten isolate 136 and bacterium Bacillus subtilis UTB22. Oven-dried specimens with dimensions of 50 mm × 25 mm × 15 mm (L × T × R) were incubated with the microorganisms at (23±2) °C and (65±5) % relative humidity for six weeks. The control and exposed wood blocks were then pressure treated by 1 % fluorescent dye (fluorescein)-containing water to study the treatability pattern under a fluorescence microscope. The longitudinal and tangential air permeability and compression strength parallel to the grain of the specimens were also determined at the end of the incubation period. Scanning electron microscopic (SEM) studies showed that degradation by B. subtilis UTB22 was limited to the pit membranes, but the cell walls were also degraded to some extent by P. vitreus. The fungus caused a higher mass loss compared to the bacterium, whereas the permeability enhancing ability of the bacterium was more pronounced. The fluorescent dye tracer also showed that higher treatability with more uniformity was obtained by B. subtilis UTB22. The improvement in treatability by both microorganisms was mainly due to the degradation of the earlywood tracheids.


2021 ◽  
Vol 72 (4) ◽  
pp. 327-336
Author(s):  
Bita Moezzipour ◽  
Sahab Hedjazi ◽  
Hossein Yousefi ◽  
Mohammad Ahmadi

The present research has primarily focused on the production of nanofibrillated lignocellulose (NFLC) instead of nanofibrillated cellulose (NFC), which could be produced with less energy and is expected to have similar uses as NFC, especially in the sectors where the transparency is not important. Furthermore, the effect of energy consumption needed for NFLC production and also the influence of pulping methods on the produced NFLC properties has been surveyed. Through mechanical refining and different passes in microfluidizer, the results showed the average diameter of NFLC declined from around 19000 nm to 36 nm. Soda-NFLC films had higher calliper and lower roughness, compared to those of MEA at given energy consumption in refiner and microfluidizer. For both kinds of pulps, the optimum level of energy consumption to reach the best tensile index of NFLC films was 258 kWh/t, with three passes through microfluidizer. More increase in the number of passes and pressure only resulted in increasing of energy consumption without any positive effect on improving the tensile index. The maximum tensile indices of NFLC films obtained from soda and MEA pulping processes were 113.5 and 119.86 N·m/g, respectively. The burst index of 8.5 kP·m2/g and the energy consumption of 458 kWh/t were obtained for five passes through microfluidizer. With the increase of the number of passes of soda and MEA samples through microfluidizer, the opacity decreased but transparency increased.


2021 ◽  
Vol 72 (4) ◽  
pp. 381-388
Author(s):  
Mirko Kariz ◽  
Manja Kitek Kuzman ◽  
Milan Šernek

The influence of artificial ageing on bonded heat-treated spruce lamellas was investigated. Heat-treated spruce lamellas with different degrees of thermal modification were bonded with PVAc and MUF and then exposed to 500 artificial weathering cycles, combined with rain, UV and IR radiation. The colour change of the exposed surface, weight change, delamination of the bonded joints and adhesive bond strength were measured. Artificial weathering caused cracking and delamination of the bonded joints and reduced the bond strength of both adhesives. The results show that delamination was higher for PVAc adhesive than MUF, but increased for both adhesives with the temperature of heat treatment of wood. The shear strength of bonds on the exposed side of the samples after the artificial weathering was lower than the average strength of the whole sample.


2021 ◽  
Vol 72 (4) ◽  
pp. 347-352
Author(s):  
Ahad Furugi ◽  
Fatih Yapici

Optimization of process conditions in oriented strand board (OSB) manufacturing is a very important issue for both reducing cost and improving the quality of panels. Taguchi experimental design technique was applied to determination and optimization of the most influential controlling parameters of OSB panels such as press condition (pressure-time-temperature) and the ratio of adhesive parameters on modulus of elasticity (MOE). The value of the MOE is one of the very important mechanical properties of OSB panels. For this purpose, several experiments were conducted according to Taguchi L27 orthogonal design. The signal-to-noise (S/N) and the analysis of variance (ANOVA) were used to find the optimum levels and to indicate the impact of the controlling parameters on MOE. A verification test was also performed to prove the effectiveness of Taguchi technique. Since the predicted and the measured values were very close to each other, it was concluded that the Taguchi method was very successful in the optimization of effective parameters in OSB’s manufacturing.


2021 ◽  
Vol 72 (4) ◽  
pp. 353-363
Author(s):  
Huseyin Pelit ◽  
Ali Alkan ◽  
Mesut Yalcin

In this study, the effect of impregnation with natural extracts on decay resistance and color change of pine and beech wood was analyzed. Flowers of Rhododendron luteum and Rhododendron ponticum plants were extracted according to the decoction method and aqueous solutions were prepared at different concentration levels (2 %, 4 % and 7 %). In addition, ferrous sulfate, copper sulfate and aluminum sulfate mordants were added to the solution to improve the properties of the extracts. Then the wood specimens were impregnated with the prepared solutions. The results indicated that the effect of plant species on the mass loss of specimens exposed to T. versicolor (white-rot fungus) was insignificant. Non-mordant extracts had a slight effect on the mass loss of the specimens. However, in pine and beech specimens impregnated with mordant-added (especially ferrous sulfate-added) extracts, mass loss was significantly reduced and resistance to fungal rot was almost completely achieved. The concentration level did not have a significant effect on the mass loss of specimens treated with mordant-added extracts. After impregnation, the L* value of all specimens (especially those treated with ferrous sulfate-added extracts) decreased and the specimens darkened. The a* and b* values increased in specimens treated with non-mordant and aluminum sulfate-added extracts and these specimens tend to have a red-yellow color. The a* value decreased and the b* value increased in wood specimens treated with copper sulfate-added extracts. The green-yellow color trend of these specimens increased. Both the a* and b* values of the specimens treated with ferrous sulfate-added extracts decreased and the green-blue color tendency increased in these specimens. The increase in the concentration level positively affected the determined color changes. The total color change (ΔE*) was higher in wood specimens (especially pine) treated with ferrous sulfate-added R. ponticum extracts.


2021 ◽  
Vol 72 (4) ◽  
pp. 403-410
Author(s):  
Slavica Petrović

Serbia is one of the few European countries that does not keep official statistics and does not have data on heating degree days. A heating degree day (HDD) represents a measure to quantify the energy needs for heating a building. In order to create a database, six meteorological stations in Serbia had been selected, for which the heating degree days were calculated for every year in the period 2010-2018. The months with the highest values of heating degree days were also determined for each year of the analyzed period. In addition to the annual level, heating degree days in the heating seasons over the analyzed period were calculated for the six selected stations, as well as the length and the average air temperature of each heating season. In Serbia, heating season officially lasts from October 15 to April 15. To determine the influence of the calculated annual heating degree days on fuelwood consumption in households in Serbia, over the period 2010-2018, multiple econometric models were formulated. The influence of the annual values of heating degree days on fuelwood consumption for household space heating in Slovenia and Croatia was analyzed, as well. The analysis of energy consumption in the households of the selected countries showed that wood fuels are mostly used for heating, primarily fuelwood. This is the reason why this type of fuel was selected for the research.


2021 ◽  
Vol 72 (4) ◽  
pp. 373-379
Author(s):  
Ljiljana Kozarić ◽  
Smilja Bursać ◽  
Martina Vojnić Purčar ◽  
Miroslav Bešević ◽  
Žikica Tekić

The aim of this paper is to present numerical investigations of dynamic characteristics and bending stiffness for cross laminated timber floor panels with and without service openings. Five-layer panels with the outer layers oriented in the longitudinal direction of the panel have been analyzed. In order to explore the full potential of this floor system using a limited number of measurements and structural tests, models based on the finite element method have been proposed, validated against experimental results and then used to investigate the effect of opening position in the floor on main structural performance parameters. The results showed that, when the need for additional service opening appears, a slight decrease of the main structural characteristics of the cross laminated timber floor panels is achievable with an adequate geometrical position of the opening in the floor.


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