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In this study, the effect of the amount of maleic anhydride grafted polypropylene (PP-g-MA) (0–10 by weight %) compatibilizer on the thermal and mechanical properties of polypropylene/post-consumer ...poly (ethylene terephthalate) (PP/rPET) (70/30 by weight %) blends are investigated by means of melt blending method. Post-consumer PET bottle waste was recycled by means of bottle-to-bottle recycling method. The interactions between the polymers of the blends and PP-g-MA were investigated by means of Fourier transform infrared spectrometer (FTIR). The scanning electron microscope (SEM) results showed that the interfacial interactions of the polymers of studied blends improved with the increasing amount of PP-g-MA. The effect of the amount of PP-g-MA on the mechanical properties of the blends were investigated by means of tensile and flexural tests. It was obtained from mechanical tests that the tensile strength, tensile modulus, flexural strength and flexural modulus increased while elongation at break decreased with the increasing amount of PP-g-MA. The best mechanical performances were obtained by compatibilized PP/rPET blends with a tensile modulus value of 1795 MPa and flexural modulus value of 2515 MPa. The effect of the amount of PP-g-MA on the thermal properties of the blends were investigated by means of differential scanning calorimeter (DSC) and heat deflection temperature (HDT) tests. It was observed that the crystallization temperature (T
c
) and HDT of the blends increased with the increasing amount of PP-g-MA.
The processing of wood-based panels such as plywood, particleboard and fiberboard, which are widely used in the furniture industry, with CNC (Computer Numerical Control) milling machines has been ...increasing recently. Even though CNC milling machines have many advantages for furniture producers, it is difficult to set process parameters to obtain the desired surface quality of the material. Therefore, it is necessary to determine the most suitable of these parameters for the surface quality of each wood-based panel. This study aimed to determine the effects of processing parameters on the surface quality of plywood, particleboard and medium density fiberboard (MDF) panels processed in CNC milling machines. Furthermore, the average surface roughness values of these panels were compared after CNC processing. Three spindle rotational frequencies (10.000, 14.000 and 18.000 rpm), three feed rates (5, 7, and 9 m/min) and two cutting tool diameters (2 and 5 mm) were selected as CNC processing parameters. To determine the surface quality of wood-based panels, the surface roughness measurements were performed according to DIN 4768 standard and three surface roughness parameters (Ra, Rmax and Rz) were determined. According to the results of this study, it can be concluded that the surface roughness values of wood-based panels decreased with increasing spindle rotational frequency and feed rate, while they increased with increasing cutting tool diameter. Among the wood-based panels used in this study, the lowest average roughness values were obtained for plywood samples.
Za obradu ploča na bazi drva kao što su furnirske ploče, iverice i vlaknatice, koje imaju široku primjenu u industriji namještaja, u posljednje se vrijeme sve češće primjenjuju CNC (Computer Numerical Control) glodalice. Iako CNC glodalice imaju mnoge prednosti za proizvođače namještaja, teško je odrediti parametre procesa za postizanje željene kvalitete površine obrađivanog materijala. Stoga je potrebno odrediti najprikladnije parametre obrade za svaku vrstu ploče na bazi drva. Cilj ovog istraživanja bio je utvrditi utjecaj parametara obrade CNC glodalicama na kvalitetu površine furnirske ploče, iverice i ploče vlaknatice srednje gustoće (MDF ploče). Nadalje, uspoređene su srednje vrijednosti hrapavosti površine tih ploča nakon CNC obrade. Kao parametri CNC obrade odabrane su tri frekvencije vrtnje vretena (10 000, 14 000 i 18 000 okr./min), tri posmične brzine (5, 7 i 9 m/min) te dva promjera reznog alata (2 i 5 mm). Za određivanje kvalitete površine ploča na bazi drva provedena su mjerenja hrapavosti površine prema normi DIN 4768, a hrapavost je iskazana trima parametrima hrapavosti površine (Ra, Rmax i Rz). Prema rezultatima ovog istraživanja može se zaključiti da su se vrijednosti hrapavosti površine ploča na bazi drva smanjivale s povećanjem frekvencije vrtnje vretena i posmične brzine, dok su se povećavale s povećanjem promjera reznog alata. Među pločama na bazi drva na kojima je provedeno ovo istraživanje najniže srednje vrijednosti hrapavosti dobivene su za uzorke furnirske ploče.
Wooden buildings are intensely preferred especially in earthquake regions due to their many advantages such as lightness, durability, environmental friendliness, insulation and aesthetics. Shear ...walls provide the lateral resistance needed for light-frame wood structures to withstand earthquake loads. When sheathed with wooden structural panels such as plywood, shear walls can be strong, stiff, and ductile. This study focuses on the effects of production factors (wood species, thickness of panels) of plywood and fibre direction of sheathing material on the racking performance of the shear wall. The displacement at ultimate load decreased with increasing the thickness of plywood panels. It was also concluded that the black pine plywood panels were the best sheathing materials for the shear walls among wood species in terms of ductility. Scots pine plywood panels are the best sheathing materials for the shear walls among wood species in terms of load carrying capacity. Moreover, it was found that the wall formed perpendicular to fibre direction of sheathing materials could carry more load than the wall formed parallel to fibre direction.
U potresnim su područjima osobito zastupljene drvene građevine zbog njihovih brojnih prednosti kao što su lakoća, trajnost, ekološka prihvatljivost, izolacija i estetika. Posmični zidovi osiguravaju bočnu otpornost kako bi lagane drvene konstrukcije izdržale potresna opterećenja. Kada su obloženi drvenim strukturnim pločama kao što je furnirska ploča, posmični zidovi mogu biti jaki, kruti i duktilni. Ovo je istraživanje fokusirano na učinke proizvodnih čimbenika furnirske ploče (vrstu drva, debljinu ploče) te na smjer vlakanaca materijala za oblaganje na svojstva posmičnog zida. Pokazalo se da se s povećanjem debljine furnirske ploče smanjuje pomak pri krajnjem opterećenju. Također je zaključeno da su sa stajališta duktilnosti furnirske ploče od drva crnog bora bolji izbor za oblaganje posmičnih zidova nego furnirske ploče od ostalih istraživanih vrsta drva. Sa stajališta nosivosti, za oblaganje posmičnih zidova najboljima su se pokazale furnirske ploče od drva bijelog bora. Osim toga, utvrđeno je da zid formiran okomito na smjer vlakanaca materijala za oblaganje može nositi veće opterećenje nego zid formiran paralelno sa smjerom vlakanaca materijala za oblaganje.
This study investigated the effects of different fire retardant chemicals on surface and thermal properties of veneer sheets. Beech (Fagus orientalis), alder (Alnus glutinosa), poplar (Populus ...deltoides) and scots pine (Pinus sylvestris) were chosen as wood species and zinc borate, borax, monoammonium phosphate and ammonium sulfate were chosen as fire retardant chemicals. The samples were impregnated by using the immersion method. Some surface properties such as colour measurements and surface roughness of the veneer sheets were conducted according to CIE L*a*b* system. Some thermal properties such as thermal conductivity of the veneer sheets were conducted according to standard and weight loss after combustion was determined by thermogravimetric analysis (TGA). Conforming to the results from the study, it was found that fire retardant chemicals increased the thermal conductivity and surface roughness of veneer sheets. Also, TGA experiments showed that all of the fire retardant chemicals decreased the loss in weights.
Polypropylene (PP)/postconsumer recycled poly(ethylene terephthalate) (rPET) blend has gained much attention as an environmentally friendly and economical material in various industrial applications. ...The aim of this study is to improve the properties of PP/rPET blend with talc, glass fiber, and carbon fiber mixture to be included by twin-screw extrusion followed by injection molding. Maleic anhydride grafted polypropylene (PP-
g
-MA) and chain extender (Joncryl ADR 4368) were used as the coupling agent. The effects of various coupling agents were evaluated in terms of the mechanical, morphological, electrical, and thermal properties of the PP/rPET hybrid composites. The mechanical properties of the composites were characterized by tensile and Charpy impact tests. Scanning electron microscopy (SEM) was used to assess the fracture surface morphology and the dispersion of the filler. The thermal properties of the composites were characterized using differential scanning calorimeter (DSC), heat deflection temperature (HDT), and Vicat softening temperature (VST) tests. The results showed that the composites morphology was dramatically affected by the addition of coupling agent. Tensile and impact strength increased in the presence of coupling agent of the composite due to the improved interaction at the interface of polymers. HDT and VST of the composite were increased significantly in the presence of PP-
g
-MA.
Graphical abstract
Moisture content (MC) is one of the most important factors that can affect many physical and mechanical properties of wood and veneers. MC strongly affects the final strength and durability of ...joints, development of surface checks in the wood and dimensional stability of the bonded assembly. In this study, plywood panels made from Alnus glutinosa (alder), Fagus orientalis (beech) and Picea orientalis (spruce) wood veneers were treated with ammonium acetate, borax and boric acid by using dipping method to test for their equilibrium moisture content (EMC). Borax and boric acid solutions were used for fire-retardancy, and ammonium acetate for reducing formaldehyde emission. Two different veneer drying temperatures (20ºC and 180ºC) were used to reveal the effects of veneer drying at high temperature on the hygroscopicity of plywood panels. EMC values of alder, beech and spruce panels decreased significantly with veneer drying at high temperature. Picea orientalis (spruce) plywood panels had the highest EMC values and followed by Alnus glutinosa (alder) and Fagus orientalis (beech) panels. EMC values of plywood panels increased significantly for both drying temperatures after ammonium acetate, borax and boric acid treatments.
Bezoar is described as a swallowed, extraneous, and indigestible mass located in the gastrointestinal system; it accounts for 0.4-4.0% of all cases of mechanical intestinal obstruction. Intestinal ...obstruction is the most frequent complication of bezoar formation. Apart from intestinal obstructions, bezoars may also exhibit clinical symptoms such as abdominal pain, nausea, vomiting, weight loss, upper gastrointestinal bleeding, and gastric perforation. However, a considerable number of cases tend to be asymptomatic. Of note, its clinical symptoms cannot be differentiated easily from intestinal obstructions caused by other factors. As such, preoperative CT examination can provide invaluable information about the level of obstruction, etiology, and the existence of additional pathology and thereby help plan the type of surgical procedure required. If prompt diagnosis and timely treatment are not carried out, the condition may lead to significant morbidity and mortality.
The aim of this paper was the deduction of a new stage-discharge relationship for a contracted weir, having a crest length less than the channel width, by using the Malcherek’s outflow theory. The ...average outflow velocity over the rectangular contracted weir was expressed in terms of the head over weir, the momentum correction coefficient and the ratio between the crest length and the channel width. This theoretically deduced stage-discharge formula was calibrated by measurements carried out for values of the ratio between the crest length and the channel width ranging from 0.3125 to 0.9375. In particular, a relationship to estimate the momentum correction coefficient for contracted weirs was deduced. The analysis showed that the proposed stage-discharge relationship is characterised by an excellent performance and allows to measure discharge values characterised by errors which are, for 96.0% of the measured values, less than or equal to ±5%.
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