39 research outputs found
Metode ekstrakcije brnistre ili žuke (Spartium Junceum L.)
Effects of different extraction methods of the Spanish Broom shoots were measured and compared with the purpose of obtaining composite material. The content of cellulose, lignin, pentosan and ash in the Spanish Broom fibers was determined. SEM analyses were performed.Mjereni su i usporeÄeni uÄinci razliÄitih postupaka maceracije izbojaka brnistre, radi upotrebe prirodnih vlakana u procesu dobivanja kompozitnih materijala. UsporeÄeni su FTIR spektri nekih prirodnih vlakana, kao i FTIR spektri vlakana dobivenih razliÄitim postupcima maceracije. U vlaknima brnistre odreÄen je sadržaj celuloze, lignina, pentosana i pepela. Obavljene su SEM analize izbojka brnistre
Utjecaj modifikacije karbamid-formaldehidne smole s utekuÄenim drvom na svojstva ploÄa iverica
In the group of wood composite materials from fragmented wood, āvaluelessā biomass and residues are converted to valuable material. The problem of application of other necessary synthetic chemical components, particularly adhesives, which are essential non-wooden components in wood composite production (mainly oil derivatives), has been the subject of many scientific researches that gave positive results. Further to the above, many researches are focused on wood liquefaction and liquefied wood (LW) application as potential adhesives, related to gluing solid particles with liquid wood. Based on previous studies, maximum attention was given to LW applications in modification of phenol-formaldehyde (PF) resins, polyurethanes, saturated and unsaturated polyesters, isocyanates and epoxy resins, and their further application in novel material types. It is evident that because of their āinferiorā properties, researches on urea-formaldehyde (UF) resins failed, as well as researches on preparations of UF base adhesives modified with LW. Therefore, the subject of this study was to research the influence of specific experimental parameters on liquefied wood compatibility with UF resins, its influence on polymer structure and adhesion-cohesion properties of modified UF adhesives, and particleboard physical mechanical properties and formaldehyde emission. The results showed that in all cases of UF resin replacement with LW, there was a significant reduction of formaldehyde emission in particleboards, which is one of the aims of this study. Furthermore, it was shown that LW does not show any polymer or adhesion properties, and in this regard laboratory synthesis was conducted of designed liquefied wood-formaldehyde (LWF) resin and LW was synthesized with formalin. With the LWF resin modification of particleboards, results showed increased mechanical properties and free formaldehyde emission as a direct influence of added formalin. To reduce the increased free formaldehyde emission, LWF resin was synthesized analogously to the production of PF resin novolak type, and prepared based on the percentage of lignin content (because of polyphenol properties) in investigated wood species (black poplar), which was applied in further researches.U drvnim kompozitnim materijalima od usitnjenog drva ābezvrijednaā se biomasa i ostaci nakon uporabe pretvaraju u vrijedan materijal. Problem primjene ostalih nužnih sintetiÄkih kemijskih komponenata, osobito ljepila koja su esencijalne nedrvne komponente u proizvodnji drvnih kompozita (uglavnom naftni derivati), veÄ je odavno predmetom znanstvenih istraživanja koja daju pozitivne rezultate. Vezano za navedenu problematiku, brojna su istraživanja usmjerena na utekuÄenje drva i primjenu utekuÄenog drva kao ljepila, odnosno na lijepljenje krutih drvnih Äestica tekuÄim drvom. Na temelju dosadaÅ”njih istraživanja, najviÅ”e je pozornosti pridano primjeni utekuÄenog drva u modifikaciji fenol-formaldehidnih (FF) smola, poliuretana, zasiÄenih i nezasiÄenih poliestera, izocijanata i epoksidnih smola te njihovoj daljnjoj primjeni u novim vrstama materijala. Evidentno je da su zbog njihovih āloÅ”ijihā svojstava, istraživanja karbamid-formaldehidnih (KF) smola modificiranih utekuÄenim drvom izostala. Stoga je predmet istraživanja ovog rada utjecaj eksperimentalnih parametara na kompatibilnost utekuÄenog drva s KF smolama, utjecaj na polimernu strukturu i adhezijsko-kohezijska svojstva modificiranih KF ljepila te na fizikalno-mehaniÄka svojstva i emisiju formaldehida ploÄa iverica. Rezultati su pokazali da je u svim primjerima zamjene KF smole UD-om znatno smanjena emisija formaldehida u ploÄama ivericama, Å”to je i jedan od ciljeva ovog rada. Nadalje, pokazalo se da UD ne pokazuje polimerna ni vezivna svojstva, te je u tom smislu provedena laboratorijska sinteza projektirane utekuÄeno drvo-formaldehidne (UDF) smole, odnosno UD je sintetiziran formalinom. Modifikacijom ploÄa iverica UDF smolom, rezultati su pokazali poveÄana mehaniÄka svojstva i emisiju slobodnog formaldehida kao izravan utjecaj dodanog formalina. Da bi se smanjila poveÄana emisija slobodnog formaldehida, UDF smola sintetizirana je analogno proizvodnji FF smola novolaÄnog tipa, te je pripravljena na temelju postotka sadržaja lignina (zbog polifenolnih svojstava) u istraživanoj vrsti drva (topolovini), te je upotrijebljena u daljnjim istraživanjima
Proces peletiranja biomase - pregled literature
A review paper was designed as a lab-scale start-up guideline for general pelletizing process and technologies for biomass feedstock. The main body consists of summarized published research on the topic of all main parts of the biomass pelletizing process and technology, including machinery and their parts, optimal feedstock conditions as well as pellet forming processes and principles. This paper is more focused on the specific parameters necessary to obtain optimal pelletizing process that results in desired pellet quality, and less on feedstock preparation, final product post-treatment (e.g. cooling), handling (storage, transportation) or exact quality specifications. A summary of the suggested feedstock, technological and other parameters for the purpose of easier lab-scale start-up of biomass pellets production, which is based on the cited literature throughout this paper, is given in the last section.Pregledni rad pripremljen je kao laboratorijski priruÄni materijal za osnovne procese i tehnologije peletiranja biomase. U njemu su sistematizirane spoznaje iz dostupnih izvora literature o temi glavnih dijelova procesa i tehnologije peletiranja biomase, ukljuÄujuÄi strojeve i njihove pripadajuÄe dijelove, optimalne ulazne parametre sirovine, kao i naÄela i procese izrade peleta. Ovaj je priruÄni materijal viÅ”e usmjeren na specifiÄne parametre nužne za optimalan proces peletiranja radi dobivanja peleta željene kvalitete, a manje na pripremu sirovine, tretiranje proizvedenog peleta (npr. hlaÄenje), rukovanje peletima (skladiÅ”tenje, transport) ili na odreÄena kvalitativna svojstva peleta. Sažetak preporuÄenih tehnoloÅ”kih parametara i ulaznih parametara sirovine, koji se temelji na informacijama iz navedene i citirane literature, nalazi se na kraju ovoga preglednog rada
Influence of plywood grain direction on sandwich panel bending properties
U radu je istraživan utjecaj varijacije kuta vlakanaca u furnirskoj ploÄi na savojna svojstva sendviÄ-ploÄe te na naprezanja u pojedinim slojevima. Eksperimentalne sendviÄ-ploÄe (tnom= 29 mm) izraÄene su od dvije troslojne furnirske ploÄe i krute PVC srednjice izmeÄu njih. Kutovi vlakanaca vanjskih slojeva furnirskih ploÄa kretali su se u rasponu od 0 do 90Ā° kontinuirano rastuÄi po 15Ā°. Ukupno je izraÄeno sedam modela sendviÄ-ploÄa. Savojna svojstva sendviÄ ploÄe odreÄena su metodom s tri uporiÅ”ne toÄke, a naprezanja u njihovim pojedinim slojevima dobivena su uporabom raÄunalnoga simulacijskog programa, tj. metodom konaÄnih elemenata. Simulacijski modeli kreirani su prema jednakim uvjetima optereÄenja kao i pri empirijskom mjerenju savojnih svojstava eksperimentalne sendviÄ-ploÄe. Rezultati istraživanja pokazuju da varijacija kuta vlakanaca ima velik utjecaj na promjenu savojnih svojstava sendviÄ-ploÄe, kao i na veliÄinu naprezanja u pojedinim njezinim slojevima. Rezultati takoÄer upuÄuju na važnost analiziranja naprezanja u svakom sloju furnirske ploÄe, radi izbjegavanja koncentracije naprezanja u pojedinim slojevima, s ciljem optimizacije strukturne konstrukcije sendviÄ-ploÄe. Takve vrste analize naprezanja ne obuhvaÄaju se standardiziranim empirijskim metodama odreÄivanja savojnih svojstava sendviÄ- ploÄe.This paper investigates the influence of plywood grain direction on bending properties of a sandwich panel, as well as on stress distribution in each layer. Experimental sandwich panels (tnom= 29 mm) were made of two three-ply plywood panels and a rigid PVC core between them. Grain directions of plywood panels were
between 0Ā° and 90Ā°, continuously raised by 15Ā°. Seven models of sandwich panels were made. Bending properties of a sandwich panel was determined by three point bending method and stress in each layer was determined by using finite element method. Simulation models were developed with equal load conditions as applied during empirical measurement of bending properties of the sandwich panel. The research results show that grain direction has a great influence on bending properties of the sandwich panel, as well as on stress values in each layer. Results also indicate the importance of analyzing stress in each layer of plywood for the purpose of avoiding stress concentration in respective layers and for optimizing structural construction of the sandwich panel. Such stress analyses are not covered by standardized empirical methods for determining bending properties of sandwich panels
Basic Materials for Manufacturing Wood-Plastic Composites
U ovom radu sumirana su i sistematizirana dosadaÅ”nja istraživanja svojstava osnovnih materijala za proizvodnju drvno-plastiÄnih kompozita (engl. Wood-plastic composites ā WPC). Analizirana su svojstva drvnih i polimernih materijala, te njihov utjecaj na preradivost, te fi zikalna i mehaniÄka svojstva kompozita u uvjetima uporabe. WPC ima vrlo dobra svojstva u razliÄitim uvjetima uporabe, te se pokazao kao jedno od rjeÅ”enja problema prikladnog zbrinjavanja sve veÄe koliÄine organskog i plastiÄnog ostatka. SpecifiÄnosti pojedinih vrsta osnovnih drvnih i plastiÄnih materijala, moguÄnosti njihove modifikacije i razne kombinacije omoguÄuju izradu razliÄitih tipova kompozita, a time i oblikovanje krajnjih proizvoda toÄno odreÄenih svojstava. Udio sintetiÄkih polimera i dodataka za poboljÅ”anje strukture kompozita ne Äini ih u potpunosti ekoloÅ”ki prihvatljivim materijalima, no WPC materijale potrebno je unapreÄivati i, opÄenito, Å”iriti njihovu uporabu.This paper summarizes and systemizes research results of the characteristics of the basic materials for manufacturing wood-plastic composites (WPC). The properties of wood and polymer materials are discussed as well as their impact on processing, physical and mechanical properties and composite properties under conditions of use. WPCs have very good properties in different conditions of use, and they proved to be one of the solutions for proper disposal of ever increasing quantities of organic and plastic residues. Specific features of certain types of the basic organic and plastic materials, the possibility of their modifi cation and combination of materials, enable the production of different types of composites, and also of forming final products of specific characteristics. Due to the presence of synthetic polymers and additives for structural improvement of composites, these materials are not completely environmentally friendly, but efforts should be taken to improve the WPCs and generally to increase their use
Basic Materials for Manufacturing Wood-Plastic Composites
U ovom radu sumirana su i sistematizirana dosadaÅ”nja istraživanja svojstava osnovnih materijala za proizvodnju drvno-plastiÄnih kompozita (engl. Wood-plastic composites ā WPC). Analizirana su svojstva drvnih i polimernih materijala, te njihov utjecaj na preradivost, te fi zikalna i mehaniÄka svojstva kompozita u uvjetima uporabe. WPC ima vrlo dobra svojstva u razliÄitim uvjetima uporabe, te se pokazao kao jedno od rjeÅ”enja problema prikladnog zbrinjavanja sve veÄe koliÄine organskog i plastiÄnog ostatka. SpecifiÄnosti pojedinih vrsta osnovnih drvnih i plastiÄnih materijala, moguÄnosti njihove modifikacije i razne kombinacije omoguÄuju izradu razliÄitih tipova kompozita, a time i oblikovanje krajnjih proizvoda toÄno odreÄenih svojstava. Udio sintetiÄkih polimera i dodataka za poboljÅ”anje strukture kompozita ne Äini ih u potpunosti ekoloÅ”ki prihvatljivim materijalima, no WPC materijale potrebno je unapreÄivati i, opÄenito, Å”iriti njihovu uporabu.This paper summarizes and systemizes research results of the characteristics of the basic materials for manufacturing wood-plastic composites (WPC). The properties of wood and polymer materials are discussed as well as their impact on processing, physical and mechanical properties and composite properties under conditions of use. WPCs have very good properties in different conditions of use, and they proved to be one of the solutions for proper disposal of ever increasing quantities of organic and plastic residues. Specific features of certain types of the basic organic and plastic materials, the possibility of their modifi cation and combination of materials, enable the production of different types of composites, and also of forming final products of specific characteristics. Due to the presence of synthetic polymers and additives for structural improvement of composites, these materials are not completely environmentally friendly, but efforts should be taken to improve the WPCs and generally to increase their use
Basic Materials for Manufacturing Wood-Plastic Composites
U ovom radu sumirana su i sistematizirana dosadaÅ”nja istraživanja svojstava osnovnih materijala za proizvodnju drvno-plastiÄnih kompozita (engl. Wood-plastic composites ā WPC). Analizirana su svojstva drvnih i polimernih materijala, te njihov utjecaj na preradivost, te fi zikalna i mehaniÄka svojstva kompozita u uvjetima uporabe. WPC ima vrlo dobra svojstva u razliÄitim uvjetima uporabe, te se pokazao kao jedno od rjeÅ”enja problema prikladnog zbrinjavanja sve veÄe koliÄine organskog i plastiÄnog ostatka. SpecifiÄnosti pojedinih vrsta osnovnih drvnih i plastiÄnih materijala, moguÄnosti njihove modifikacije i razne kombinacije omoguÄuju izradu razliÄitih tipova kompozita, a time i oblikovanje krajnjih proizvoda toÄno odreÄenih svojstava. Udio sintetiÄkih polimera i dodataka za poboljÅ”anje strukture kompozita ne Äini ih u potpunosti ekoloÅ”ki prihvatljivim materijalima, no WPC materijale potrebno je unapreÄivati i, opÄenito, Å”iriti njihovu uporabu.This paper summarizes and systemizes research results of the characteristics of the basic materials for manufacturing wood-plastic composites (WPC). The properties of wood and polymer materials are discussed as well as their impact on processing, physical and mechanical properties and composite properties under conditions of use. WPCs have very good properties in different conditions of use, and they proved to be one of the solutions for proper disposal of ever increasing quantities of organic and plastic residues. Specific features of certain types of the basic organic and plastic materials, the possibility of their modifi cation and combination of materials, enable the production of different types of composites, and also of forming final products of specific characteristics. Due to the presence of synthetic polymers and additives for structural improvement of composites, these materials are not completely environmentally friendly, but efforts should be taken to improve the WPCs and generally to increase their use