Syzygium album is a critically endangered species, and the wood basic properties haven’t been reported. Therefore, this paper analyzes the wood from the anatomical characteristics, physical properties, and secondary components. The results showed that observed S. album wood of a 46-year-old tree is diffuse-porous to semi-diffuse-porous wood. The maximum vessel tangential diameter is 127.47 μm, which is found at the beginning of the earlywood. The wood rays are heteromorphic type I and II, and the multi-column part is mostly 3 cells wide. In physical properties, the air-dry density is classified as “heavy”, whereas its air-dry and full-dry differential dry shrinkage are “small” and “medium”, respectively. This indicates that the wood performs better when dried. The content of benzene-ethanol extract from S. album wood is 2.10%. The benzene-ethanol extracts were analyzed by GC-MS, and the main components are 2,6,11,15-tetramethylhexadecane (3.29%), eicosamethyl cyclodecasiloxane (10.02%), octadecamethyl cyclononasiloxane (7.43%), and tetracosamethyl cyclododeca- siloxane (3.60%), etc.
Four kinds of environmental anti-mildew agents (boric acid/borax, 3-iodo-2-propynyl-butyl-carbamate (IPBC), sodium tetrafluoroborate/didecyl dimethyl ammonium chloride (NaBF4/DDAC), tebuconazole) were used to treat bamboo with different concentrations respectively. The optimal concentration of each anti-mildew agent and the comparison of the anti-mildew capacity were evaluated with Aspergillus niger, Trichoderma viride and Penicillium citrinum, respectively. The results showed that the optimal anti-mildew agent concentrations of boric acid/borax (F1), IPBC (F2), NaBF4/DDAC (F3) and tebuconazole (F4) were 3.0%, 1.5%, 0.5% and 0.4%, respectively, and the average control efficacy of the three test molds was 73.15%, 92.03%, 88.43% and 98.67%, respectively. The order of anti-mildew capability of these four anti-mildew agents with their optimal concentrations was F4 > F2 > F3 > F1.
The purpose of this research is to determine the orthotropic material properties of the Norway spruce (Picea abies) and to develop a finite element modeling technique that, when applied to an individual specimen, can properly predict the outcome of the measurement results (i.e., deflection by a predefined loading) by simulation only. For the development of the finite element model of timber beams, their unique annual ring pattern is considered. The HSV color spectrum of picture of the end grain pattern is analyzed with a photo analytical algorithm in order to separate the phases, earlywood and latewood. The determined surface ratio of the phases is used to hypothesize that the volume and surface ratios are equal. For the description of wood as a material the rule of mixtures is used. The results of the compared measurements and FE models based on the introduced hypotheses show good agreement within the linear elastic limit.
The research was based on the analysis of the density, bending strength and modulus of elasticity of 100 oak lamellae generated as small-sized production waste. In this part of the study series, the test results were presented in detail and analysed, in particularly the density distribution. Correlations between some test results have been shown. The dynamic and static test results were also compared. Despite the poor quality lamellae, the average density of the sample set corresponds to literary values and the distribution of density is normal. Specimens with low density are unsuitable for further use. But the density alone cannot be used for classification. Between static and dynamic modulus of elasticity can be found a good relationship. The relationships between density and both static and dynamic modulus of elasticity of the specimens can be considered as good, too. The best correlation is in bending tests between the deflection of the specimens in the elastic range and the bending strength.
The aim of the research was to determine the changes in susceptibility of Scots pine (Pinus sylvestris L.) wood to feeding by subterranean termites Reticulitermes lucifugus var. santonensis conducted in accordance with the ASTM D 3345-08: 2009 The sapwood after modification in furfuryl alcohol at concentration 50% with the addition citric acid at concentration 1%, natural sapwood and heartwood experiment as a compulsory reference material were used for the tests. The blocks of Scots pine wood were used to create seasoned samples of 7% ± 1% moisture content. The blocks with dimensions of 25.4 x 25.4 x 6.4 mm were made from three trees. Each variant was represented by 5 blocks. All wood blocks were freeze-dried before starting the experiment in order to measure the dry weight. After 4 weeks of termite feeding visually rates of wood destruction were: 9 (light attack) for modified sapwood, 2.8 (heavy attack/failure) for natural sapwood and 8.2 (light attack/moderate attack) for natural heartwood. The loss of wood weight of blocks was: 0.01 g for modified sapwood, 0.071 g for natural sapwood and 0.21 g for natural heartwood. The mortality of the termites in the case of modified sapwood was complete. The termite mortality in natural sapwood has been classified as slight, and in natural heartwood as slight to complete.
This research aims to address the noise pollution by developing an acoustic absorber made of polylactic acid (PLA)/polyhydroxyalkanoates (PHA)-wood fibers (PLA/PHA-WF) by compression molding (CM) and additive manufacturing (AM). Physical, mechanical, thermal, water absorption, and biodegradation properties of the developed acoustic absorbers by CM and AM were characterized and compared. Upon providing an air gap, thin absorbers developed by AM exhibit an increased and narrow acoustic peak than the CM absorbers because of the Helmholtz resonance effect due to the decreased density and increased porosity in the AM absorber. The results also show that the mechanical and thermal properties of the absorbers developed by CM and AM were almost similar and absorber developed by AM shows an increased rate of water absorption and biodegradation compared to absorber developed by CM due to the presence of porosity in the AM structure.
Wood-based composites with different ratios of wood fiber (WF)/palm kernel shell (PKS) and polyurethane (PU) content have been prepared using the wet-process method. Samples of WF85/PKS15 and WF75/PKS25 were fabricated where each sample was applied with 20% and 70% of PU contents and its physical and mechanical properties had been studied. The physical results show that the samples with 70% of PU content were denser, had low porosity, low moisture content, and low water absorption. Surface morphology observation shows both series samples with high PU content tend to form tube-like shape with different diameter. In mechanical studies, generally, the sample with high PKS and PU possesses high flexural strength, flexural modulus, tensile strength, tensile modulus, and hardness. However, the increased of PKS content in the composite reduces the tensile strength for both samples with 20% and 70% of PU. The effects of the binder and palm kernel shell in the composite were also explained. Based on the Japanese Industrial Standard (JIS) A 5905 standard, the sample composites meet the requirement under medium density fiberboard (MDF) category and classified as board type 5 which suitable as furniture, house, and automotive interior design and construction materials.
The study investigated morphology and thermal properties of cellulose/poly furfural alcohol (PFA) composites prepared from maize stalk through acid mixtures. The cellulose nanocrystals (CNCs) were extracted from maize stalk via acid hydrolysis using mixtures of various acids. The prepared CNCs were encapsulated in a PFA matrix via in situ polymerization process using p-toluene sulfonic acid as catalyst. The properties of untreated maize stalk, cellulose and their nanocomposites were analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transmission infrared (FTIR) and thermogravimetric analysis (TGA). The crystallinity of maize stalk was generally increased after an acid hydrolysis dominated by H2SO4/HNO3 and H2SO4/HCl. The same trend was observed from TGA, except that H2SO4/H3PO4 and H2SO4/HClO4 dominated thermal stability trailed by H2SO4 hydrolysed CNC nanocomposite. The surface breakage of fibers observed in SEM images was depended on the strength of acids used to hydrolysed the CNC. There was also evidence of aggregation and cracked PFA surface with addition of acid hydrolysed CNCs, dependent on the acids strength. The H2SO4/HClO4 hydrolysed CNC/PFA displayed a fairly good dispersion of CNCs in the PFA matrix with no surface breakage.
To explore the propagation law of AE signal in wood, the propagation velocity of P-wave and S-wave and the energy attenuation law of different frequency components were studied By PLB (pencil-lead break) tests. Firstly, an improved time-difference-of-arrival (TDOA) method was designed to determine the arrive time. The propagation velocities of P-wave and S-wave were calculated. Then, the Young’s modulus was estimated by P-wave velocity. Finally, on the basis of eliminating the influence of standing wave, the energy attenuation models were obtained by numerical fitting and wavelet decomposition. The results showed that the improved TDOA algorithm can calculate the propagation velocity of P-wave and S-wave at the same time through one test, and the P-wave velocity can be used to estimate the Young’s modulus. P-wave propagated faster in soft wood, while S-wave propagated faster in hard wood. The higher the frequency of AE signal, the faster the energy attenuation.
This study examined the performance of beech and self-tapping screw composite dowel applied to non-extruded L-shaped member joints and carries out theoretical calculation and analysis of stiffness. The test results indicated that eleven specimens showed three failure modes. It was found that the composite dowel had different degrees of bending phenomenon. The failure modes were also proved by the finite element analysis. Since the spruce-pine-fir was in the middle of the L-shaped specimen set in this test, it can rotate around the geometric center composed of four composite dowels.
The objectives of the study, conducted in the National Park of Bou Hedma, were to examine: (1) the relative contributions of short-term canopy (STE) and long-term soil effects (LTE) of a shrub species in explaining differences in biomass, species diversity (richness) and species density of understory plants (i) between shrubs and open areas, (ii) between shrubs and removed shrubs; and (2) the role of grazing in driving changes in direction of short-term and long-term effects in shrub/understory species interactions.
We measured environmental conditions (soil nutrients and soil water) in plots that represented different neighborhood conditions (in open areas between shrubs, amongst intact shrubs and among removed shrubs), which were either fenced or exposed to grazing by large herbivores. We also studied understory species biomass, richness, density survival rate of a target species in plots represented different neighborhood conditions. Differences in species richness, density and biomass of understorey communities between shrub removed and open areas were mostly due to long-term soil effects whereas differences below shrubs and shrub removed were due to short-term effects in particular on soil water content.
Our study provides additional evidence that savannas shrubs have the potential to increase the diversity of arid systems at the landscape level. Additionally, grazing by large herbivores influenced negatively the dynamic of vegetation under arid bioclimate.
To study the effect of retention and drainage aids on the fast-growing eucalyptus bleached kraft pulp (EBKP) suspensions, different concentrations of cationic polyacrylamide (CPAM) and cationic starch were dosed with EBKP suspensions and their effects on rheological properties were studied. The shear yield stress (τy) of softwood bleached kraft pulp (SBKP) and poplar alkaline peroxide mechanical pulp (PAPMP) were compared and evaluated for their potential applications. The results show that in the steady-state shear condition, the τy of EBKP is proportional to the pulp mass concentration (Cm), corresponding to the exponential relation . SBKP had the highest τy values, followed by EBKP and PAPMP. Adding CPAM and cationic starch to EBKP suspensions at low to moderate doses increased the τy, but once the levels reached a certain point, the τy values began to deteriorate. This research is crucial to achieve optimally and stabilize the downstream manufacturing process in papermaking.
This work assessed how to remove lignin of palm oil empty fruit bunch (EFB) in environmentally friendly method and less energy. Moreover, delignification was strengthened with additional H2O2 to perform hydroxyl radical by microwave radiation in low NaOH solution of concentration up to 0.8 M, 10%. Setting on microwave, solution was heating up and cause delignification work more effective. Observation at black liquor showed that temperature was influence by microwave radiation duration while NaOH concentration affected total suspended solid increasing. Optimally treated EFB at 0,2 M NaOH with effective lignin removal and holocellulose increasing reached 27% and 26%, respectively. Unfortunately, at higher NaOH concentration, the decomposition penetrated EFB interior, holocellulose and made lignin percentage high again. Therefore, EFB yield got less at higher NaOH concentration because more EFB was sludgy and lost during washing. XRD analysis showed the increasing crystallinity by 2.2%, closer to -cellulose. SEM showed successful impurities removal from EFB surface and Ca, Nb, Si, and Mg detected by EDS.
The effect of antenna design modification, paper substrates and relative electrical permittivity of background materials on the reflection coefficient of UHF RFID antennas was studied. Simulation software was used to modify the design and calculate the reflection coefficient of the antennas. By modifying the coupling of the dipole with the induction loop of the antennas, a reduction of the simulated reflection coefficient was achieved compared to the commercial antenna. The positive effect of antenna modification was also confirmed by measuring the reflection coefficient of antennas printed on paper by thermal transfer printing, placed on extruded polystyrene and particle board. The reflection coefficient of the modified antennas was lower when placed on extruded polystyrene, whose relative electrical permittivity was lower than particle board. After installing the memory chip to the antennas printed on paper and paperboard, the identification, reading and recording range of passive UHF RFID tags were measured after they were placed on thicker paperboard, extruded polystyrene and particle board. The positive effect of antenna modification on improving the communication quality of passive UHF RFID tags placed on background materials with a relative electrical permittivity of 2.4 to 6.7 was confirmed.
The addition of green tea leaves fractions < 0.315 mm as a filler to urea-formaldehyde resin to reduction of emission of formaldehyde from three-layer birch plywood was investigated. Moreover, other properties such as bonding quality and water resistance of plywood were investigated. It was found that green tea had an ability to absorb formaldehyde. This phenomenon was caused by phenolic compounds contained in green tea leaves. The addition of green tea in the amount of 20% and 25% resulted in a decrease in formaldehyde emission from plywood comparing to the reference sample. The bonding quality test showed that the addition of tea leaves as a filler did not affect the strength properties of the tested bond lines.