Utjecaj prirodnog izlaganja vremenskim utjecajima na svojstva kompozita od drvnog brašna i recikliranog polipropilena

In this study, the effect of natural weathering on the physical and mechanical properties of wood plastic composites (WPC) made from virgin and recycled polypropylene (PP) was studied. To prepare the recycled PP, virgin PP was thermo-mechanically degraded by extrusion under controlled conditions in a single-screw extruder at a router speed of 60 rpm and temperature of 190 °C. PP (virgin and recycled), wood flour, compatibilizer, and UV absorbent were physically blended, and the samples were manufactured by a twin-screw extruder. The samples were exposed to natural weathering for 270 days. The surface characteristics of the samples were investigated before and after weathering. According to the results, the composites from recycled PP exhibited a higher weathering resistancethan those from virgin PP. The use of a UV absorber improved the flexural strength and modulus of the composites, but it could not significantly prevent the flexural properties loss and discoloration of the composites after weathering.U ovom je istraživanju proučavan utjecaj prirodnog izlaganja vremenskim utjecajima na fizička i mehanička svojstva drvno-plastičnih kompozita (WPC) izrađenih od čistoga i recikliranog polipropilena (PP). U postupku pripreme recikliranog polipropilena čisti je polipropilen termomehanički razgrađen ekstruzijom s jednim pužem u konstantnim uvjetima i pri brzini vrtnje od 60 okr./min te pri temperaturi od 190 °C. Pomiješani su čisti i reciklirani polipropilen, drvno brašno, kompatibilizator i UV apsorber, a uzorci su proizvedeni ekstruderom s dva puža. Uzorci su bili 270 dana prirodno izloženi vremenskim utjecajima. Svojstva površine uzoraka ispitana su prije i nakon izlaganja tim utjecajima. Iz rezultata je vidljivo da su kompoziti od recikliranog polipropilena pokazali veću otpornost na vremenske utjecaje nego kompoziti od čistog polipropilena. Upotreba UV apsorbera poboljšala je čvrstoću na savijanje i modul elastičnosti kompozita, ali nije značajno spriječila slabljenje svojstava savijanja i promjenu boje kompozita nakon izlaganja vremenskim utjecajima

Effects of oleothermal treatment and polydimethylsiloxane (PDMS) coating on natural weathering of beech and fir woods

Effects of natural weathering on oleothermally treated wood and coated with an organic silicone compound were studied. Slats of beech and fir woods were cut in sizes of 20×10×1 cm. The slats were treated by soybean oil at 230˚C for 1 h. Then, the half of the untreated and oleothermally treated slats were coated with polydimethylsiloxane (PDMS) and the rest of them were considered as control. All slats were hanged in 45˚ angle at the southwest (SW) direction for 90 days. They were analyzed for color changes, roughness, and contact angle properties at 30-day intervals. Results showed that the oleothermal treatment of wood reduced discoloration of fir samples against natural weathering; however,the reducing effect was lower in the Beech samples. This treatment also reduced the surface roughness of the fir samples during weathering while it increased the surface roughness of beech. Wettability of the samples in both species, before and after weathering, was reduced by the oleothermal treatment. Results also revealed that coating of the wood surface with PDMS does not prevent the discoloration and surface roughness against weathering. Nevertheless, the coating could considerably decrease the hydrophilicity of the woods even after weathering

Influence of combined hygro-thermo-mechanical treatment on technical characteristics of poplar wood

Combined hygro-thermo-mechanical technique was adopted and used for densification of poplar wood instead of sole treatment. This technique is combination of two techniques of hygrothermal treatment and densification of wood. For treatment, poplar wood blocks were initially treated hygrothermally at temperatures of 130, 150 and 170°C for holding time of 20, 40 minutes. Afterwards, the densification process was carried out under a hot press (temperature 160°C for 20 minutes). For densification compression set was adjusted for 40 and 60 percent based on the initial thickness (radial direction) of the blocks. The densified and non-densified wood blocks were tested for physical and mechanical properties as density, water absorption, thickness swelling, springback, bending strength, modulus of elasticity as well as shear strength parallel to grain. Results revealed that wood properties were enhanced due to the combined hygro-thermo-mechanical -treatment. According to the results, wood density was increased due to the combined hygro-thermo-mechanical -treatment significantly. The treatment improved the dimensional stability of the densified samples. It was also found that the combined hygro-thermo-mechanical -treatment could significantly improve mechanical properties and also reduce the springback in the densified poplar wood

Influence of hydrothermal treatment on the dimensional stability of beech wood

Hydrothermal treatment of wood material products with many interesting properties such as enhanced dimensional stability, lower equilibrium moisture content and increased biological durability. The effects of hydrothermal treatment on dimensional stability, oven dry density and water absorption of beech wood (Fagus Orientalis) naturally grown, has been studied in present research that extremely used in Iran. Hydrothermal applied to the wood samples (2.5Cm?2.5Cm?2.5Cm) in three different temperatures (150 oC, 160 oC, 170 oC) and four different durations (1h, 3h, 5h and 7h) in reactor. Then, the samples and their controls were immersed in water at 25 oC, 65% relative humidity for various periods. Volumetric swelling percentage and rate of the water absorption values of the samples and their controls were measured at a period of 24 hour in 8 steps on basis of oven dried dimension. The obtained data were analyzed using Microsoft Office (EXCEL 2003). The data analysis indicated that best anti-swelling efficiency value was achieved at 170 oC (treating temperature) within 1 hour (treating time) and 8 steps of soaking - dried measurement by hydrothermal treatment. Consequences for anti-swelling efficiency, decreasing of samples specific gravity, water absorption and water repellency effectiveness values obtained 27.95%, 8.49%, 56.41% and 20.20% respectively. Therefore, hydrothermal treatment showed a little decreasing at 150 oC to 170oC in specific gravity of treatment samples because maximum lessening of specific gravity obtained 8.02% in the highest condition of treatmentDimensional stability after final soaking

A specific case in the classification of woods by FTIR and chemometric: discrimination of Fagales from Malpighiales

Fourier transform infrared (FTIR) spectroscopic data was used to classify wood samples from nine species within the Fagales and Malpighiales using a range of multivariate statistical methods. Taxonomic classification of the family Fagaceae and Betulaceae from Angiosperm Phylogenetic System Classification (APG II System) was successfully performed using supervised pattern recognition techniques. A methodology for wood sample discrimination was developed using both sapwood and heartwood samples. Ten and eight biomarkers emerged from the dataset to discriminate order and family, respectively. In the species studied FTIR in combination with multivariate analysis highlighted significant chemical differences in hemicelluloses, cellulose and guaiacyl (lignin) and shows promise as a suitable approach for wood sample classification

Anti-angiogenesis properties of Crocus pallasii subsp. haussknechtii, a popular ethnic food

Abstract Background and objectives: Angiogenesis is essential for tumor survival. Inhibiting angiogenesis could be a mechanism for hindering tumor development. Numerous studies have now been focused on agiogenesis inhibitors and many of such studies have targeted plant materials. In the present study, Crocus pallasii subsp. haussknechtii has been evaluated for anti-angiogenesis properties. Methods: Anti-angiogenesis activity of the plant extracts and fractions has been investigated through wound healing assay in HUV-EC-C cells. The cytotoxic activity has also been evaluated by MTT assay. Results: The methanol extract and the methanol fraction of the corm along with the chloroform fraction of the aerial parts demonstrated to be cytotoxic to HUV-EC-C cells with IC 50 values of 27.2, 74.1 and 60.0 μg/mL, respectively while the chloroform fraction of the corm showed the most considerable anti-angiogenesis property among the samples in wound healing assay. Conclusion: Regarding the results of the present study, Crocus pallasii subsp. haussknechtii is suggested for further studies in cancer research evaluations

Monitoring the cell wall characteristics of degraded beech wood by white-rot fungi: Anatomical, chemical, and photochemical study

Meticulous chemical analysis of decaying xylem and linking it to corresponding anatomical modification at the cellular level can improve our understanding of the decay process. The aim of this study was to monitor the histological, chemical, photochemical, and progression of wood degradation by two white-rot fungi at different intervals. Oriental beech wood (Fagus orientalis) blocks were exposed to Pleurotus ostreatus and Trametes versicolor to investigate the degradation capabilities of these two fungi. Light microscopy was used to study the decay patterns in wood. Decayed wood samples were also analyzed to determine lignin, cellulose and sugar contents and also evaluated at two week intervals by FT-IR spectroscopy to study chemical alterations. According to chemical analyses lignin is the most degraded polymer followed by cellulose and hemicelluloses for both white rot fungi. However, both test fungi tended to consume lignin more than cellulose. FT-IR spectra changes for  lignin and carbohydrates in beech wood supported chemical alteration and indicated that both fungi decay wood in a simultaneous pattern.&nbsp

Application of chemometric analysis to infrared spectroscopy for the identification of wood origin

Chemical characteristics of wood are used in this study for plant taxonomy classification based on the current Angiosperm Phylogeny Group classification (APG III System) for the division, class and subclass of woody plants. Infrared spectra contain information about the molecular structure and intermolecular interactions among the components in wood but the understanding of this information requires multivariate techniques for the analysis of highly dense datasets. This article is written with the purposes of specifying the chemical differences among taxonomic groups, and predicting the taxa of unknown samples with a mathematical model. Principal component analysis, t-test, stepwise discriminant analysis and linear discriminant analysis, were some of the chosen multivariate techniques. A procedure to determine the division, class, subclass and order of unknown samples was built with promising implications for future applications of Fourier Transform Infrared spectroscopy in wood taxonomy classification