Ekološki prihvatljiva uslojena drvonitna građa od lisnih osi palme datulje: analiza mehaničkih svojstava Taguchi metodom pripreme istraživanja

This study was performed to use date palm rachis, as a low value bio-waste, in the manufacture of a high value added eco-friendly structural composite lumber. Taguchi design of experiments was applied to analyse the effect of raw material and product parameters on the mechanical properties of laminated strand lumber from date palm rachis. The results indicate that the composite exhibits similar or superior strength properties compared to solid lumber and engineered products from wood or other lignocellulosic material for building sector. Taguchi design of experiments was assessed as a powerful and cost effective technique to obtain optimal levels for maximizing the mechanical properties of the environmentally-friendly composite. Maximum values for the mechanical properties of date palm rachis-based LSL were obtained from a combination of 20 mm product thickness, 10 % resin content, 4mm strand thickness, and 850 kg/m3 product density. Product thickness with an 81.3 % contribution and strand thickness with an 80 % contribution have the highest effects on the flatwise stiffness and compression strength perpendicular to grain, respectively.Ovo je istraživanje provedeno na konstrukcijskoj kompozitnoj građi proizvedenoj od lisnih osi palme datulje. Te su lisne osi odabrane kao biootpad male vrijednosti da bi se dobila građa visoke dodane vrijednosti. Taguchi metoda pripreme istraživanja primijenjena je kako bi se analizirao utjecaj sirovine i svojstava proizvoda na mehanička svojstva uslojene drvonitne građe (LSL) od lisnih osi palme datulje. Rezultati pokazuju da kompoziti imaju sličnu ili bolju čvrstoću nego masivno drvo i građevinski proizvodi od drva ili od ostalih lignoceluloznih materijala. Taguchi metoda pripreme istraživanja ocijenjena je kao pouzdana i isplativa tehnika za dobivanje optimalnih mehaničkih svojstava ekološki prihvatljivih kompozita. Najveće vrijednosti mehaničkih svojstava LSL-a od lisnih osi palme datulje dobivene su za proizvod debljine 20 mm, sa sadržajem smole od 10 %, debljine vlakana 4 mm i gustoće 850 kg/m3. Najveći utjecaj na krtost plohe i čvrstoću na tlak imaju debljina proizvoda, s 81,3 %, i debljina vlakana, s 80 % utjecaja

Kinetika konvektivnog sušenja tankog sloja iverja drva topole (Populus Deltoides)

Drying of poplar wood (Populus Deltoides) particles was carried out at different drying conditions using a laboratory convective thin layer dryer. Drying curves were plotted and in order to analyze the drying behavior, the curves were fi tted to different semi-theoretical drying kinetics models. The effective moisture diffusivity was also determined from the integrated Fick’s second law equation and correlated with temperature using an Arrhenius- type model to calculate activation energy of diffusion. The results showed that Midilli et al. model was found to satisfactorily describe the drying characteristics of poplar wood particles dried at all temperatures and air flow velocities. In general, the drying rate increases with increasing air temperature and air fl ow velocity. A short constant drying rate period was observed and drying frequently took place at falling rate period in all cases. The effective moisture diffusivity of poplar wood particles increased from 1.01E-10 to 2.53E-10 m2·s-1 as the drying air temperature increased from 65 to 85 °C. The activation energy of diffusion for 1 m·s-1 and 1.5 m·s-1 air flow velocities were calculated as 27.8 kJ·mol-1 and 50.8 kJ·mol-1, respectively.Pri različitim uvjetima sušenja provedeno je sušenje iverja drva topole (Populus deltoides) uporabom konvektivne sušionice za tanki sloj iverja. Iscrtane su krivulje sušenja, a da bi se analizirao proces sušenja, krivulje su prilagođene različitim teorijskim kinetičkim modelima sušenja. Određena je i efektivna difuznost vode u drvu prema Fickovu drugom zakonu te je primjenom Arrheniusova modela za izračun aktivacijske energije difuzije korelirana s temperaturom. Rezultati su pokazali da model Midillija i suradnika zadovoljavajuće opisuje obilježja sušenja iverja drva topole pri svim temperaturama i brzinama strujanja zraka. U načelu, brzina sušenja povećava se s povećanjem temperature zraka i brzine strujanja zraka. Zabilježeno je kratko razdoblje konstantne brzine sušenja, a sušenje se najčešće postiže u razdoblju pada brzine sušenja. Efektivna difuzivnost vode u iverju drva topole povećana je s 1,01E-10 na 2,53E-10 m2·s-1 s povećanjem temperature zraka sa 65 na 85 °C. Izračunana je aktivacijska energija difuzije za 1 m·s-1 i 1,5 m·s-1 brzine strujanja zraka i iznosi 27,8 kJ·mol-1 i 50,8 kJ·mol-1

Assessment of physical, mechanical, and biological properties of bamboo plastic composite made with polylactic acid

The effects of different mixing, bamboo mesh size and heat treatment on the physical and mechanical properties and biodegradability of a polylactic acid (PLA) composite were determined. The results indicated that this composite exhibited high strength in all mechanical properties examined, except hardness using the pure polymer (PLA). The mesh size of the bamboo flour and heat treatment had considerable effects on all tests expect the decay resistance. The water absorbance and thickness swelling of the PLA composite was reduced to nearly zero after 3000 hours immersion in water. Moreover, the fungal decay test results demonstrated that PLA was highly resistant to both Basidiomycetes and Ascomycetes fungi. The brown rot fungi, however, produced an extensive mass loss in the composite composed of different levels of bamboo flour

Oksidativna aktivacija površine vlakanaca u proizvodnji MDF ploča

This study presents the investigation of the effects of oxidant type (nitric acid and potassium dichromate), oxidant content (three different levels as 2, 4, and 6 percent) and urea- formaldehyde (UF) resin percentage (two levels as 5 and 7 percent) on mechanical and physical properties of interior grade medium density fiberboard made from bagasse fibers. Some panel properties were studied, such as modulus of rupture (MOR) and modulus of elasticity (MOE) in bending, compression-shear strength (C.S sth.), water absorption (WA) and thickness swelling (TS) after 2- and 24-hour immersion in cold water. In addition, the results indicated the best values for WA and TS after 2- and 24-hour immersion, and C.S. sth. was discerned at 7 percent UF resin content, together with 6 percent nitric acid. Furthermore, the greatest values for MOR and MOE were related to 7 percent UF resin content together with 4 percent nitric acid.U studiji je istražen utjecaj vrste oksidansa (dušične kiseline i kalijeva dikromata), sadržaja oksidansa (2, 4 i 6 %) i postotnog udjela urea-formaldehidne smole (UF) (5 i 7 %) na mehanička i fizička svojstva ploča vlaknatica srednje gustoće, proizvedenih od bagasse vlakana. Analizirana su ova svojstva ploča: modul loma (MOR) i modul elastičnosti (MOE) pri savijanju, tlačno-smicajna čvrstoća (C.S sth.) te upijanje vode (WA) i debljinsko bubrenje (TS) nakon 2 i 24 sata potapanja u hladnoj vodi. Rezultati su pokazali najbolje vrijednosti za WA i TS nakon 2 i 24 sata potapanja, te za C.S sth. pri 7 %-tnom sadržaju UF smole i pri 6 % dušične kiseline. Nadalje, najveće vrijednosti za MOR i MOE zabilježene su pri 7 %-tnom sadržaju UF smole i pri 4 % dušične kiseline

The importance of biogenic carbon storage in the greenhouse gas footprint of medium density fiberboard from poplar wood and bagasse

Carbon storage in long-lived bio-based products is typically ignored or accounted for in a simplistic way in greenhouse gas (GHG) footprint calculations. We quantified the GHG footprint of medium density fiberboard (MDF) in Iran from poplar wood and bagasse, a by-product from sugarcane production. Inventory data was collected from sugarcane and poplar wood plantations and MDF factories in Iran during 2017–2019 to calculate cradle-to-grave footprints for 1 ​m3 of MDF. We quantify the effect of carbon storage, which depends on the crop rotation time and the economic lifetime of the product, with shorter rotation times and longer storage periods leading to lower footprints. Cradle-to-grave GHG footprints of poplar and bagasse-based MDF without accounting for biogenic carbon storage are 6.8·102 ​kg CO2-eq/m3 and 8.5·102 ​kg CO2-eq/m3, respectively. Footprints are higher for bagasse-based MDF than for poplar-based MDF because of a higher electricity use, higher resin use and larger transport distances in Iran. Taking into account carbon storage periods of 10–60 years decreases the footprints to 345–655 ​kg CO2-eq/m3 for poplar-based MDF and 292–771 ​kg CO2-eq/m3 for bagasse-based MDF. These results emphasize the importance of appropriately accounting for biogenic carbon storage in GHG footprint calculations of long-lived bio based products

Assessment of physical, mechanical, and biological properties of bamboo plastic composite made with polylactic acid

The effects of different mixing, bamboo mesh size and heat treatment on the physical and mechanical properties and biodegradability of a polylactic acid (PLA) composite were determined. The results indicated that this composite exhibited high strength in all mechanical properties examined, except hardness using the pure polymer (PLA). The mesh size of the bamboo flour and heat treatment had considerable effects on all tests expect the decay resistance. The water absorbance and thickness swelling of the PLA composite was reduced to nearly zero after 3000 hours immersion in water. Moreover, the fungal decay test results demonstrated that PLA was highly resistant to both Basidiomycetes and Ascomycetes fungi. The brown rot fungi, however, produced an extensive mass loss in the composite composed of different levels of bamboo flour

Investigation on Phoenix dactylifera/Calotropis procera Fibre-Reinforced Epoxy Hybrid Composites

This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin hybrid composites with different structures, manufactured using midrib long fibres of date palm (Phoenix dactylifera L.) and Calotropis procera fibres. The two types of fibres were formed into flat sheets, without adding other chemicals or resins, and employed as reinforcing layers in the structure of the multi-layered laminate composites. Three-layer and five-layer epoxy-reinforced laminates were manufactured from the sheets of date-palm fibres and Calotropis sheets bonded with laminar epoxy resin. Water resistance investigation and mechanical testing under tensile, bending and impact loads were conducted in the research in order to evaluate and compare the performance of the resulting composites. Emphasis was put on the effect of various factors, such as the type of reinforcement material and the number of plies in the laminate on the mechanical behavior of the composites. The interpretation of those results was supported by the stereo-microscopic investigation of the adhesion between the layers of the composites, and the vertical density profile (VDP), which showed the repartition of the density on the composite thickness depending on the layer material. The results of the mechanical performance of the composites showed lower values of tensile strength, tensile modulus of elasticity and impact resistance and an increase of water absorption (WA) and thickness swelling (TS) for the five-layer composites compared to the three-layer composites. Contrarily, the addition of Calotropis fibres improved the flexural strength and the flexural modulus of elasticity. The alkali treatment of the Calotropis fibres improved the mechanical performance of the composites compared to the ones made with untreated fibres, because of an apparent increase in cellulose content and free hydroxyl groups revealed by FTIR spectra