Academic literature on the topic 'Biokompozity'

Polilaktidna kiselina (PLA) i bakterijska nanoceluloza (BNC) zbog svoje biorazgradljivosti, biokompatibilnosti i netoksičnosti imaju velik potencijal za primjenu u biomedicini. Cilj ovog rada bio je pripraviti i ispitati biokompozit PLA/BNC. Istražen je utjecaj BNC-a na morfološku strukturu, kemijski sastav, toplinska svojstva, toplinsku postojanost i hidrofobnost PLA te zasijavanje i rast stanica biokompozita PLA/BNC primjenom pretražnog elektronskog mikroskopa (SEM), infracrvene spektroskopije (FTIR), diferencijalne pretražne kalorimetrije (DSC) i termogravimetrijske analize (TGA) te određivanjem kontaktnog kuta i metodom MTT. Dodatkom BNC-a u PLA dolazi do pomaka staklišta (<i>T</i><sub>g</sub>) prema nižim temperaturama, što ukazuje na veću pokretljivost amorfne faze PLA te porasta stupnja kristalnosti zbog nukleacijskog učinka celuloze. Početak toplinske razgradnje pomaknut je na niže temperature u odnosu na čisti PLA, što ukazuje na smanjenje toplinske postojanosti PLA dodatkom BNC-a. Biokompozit PLA/BNC pokazuje poroznu, vlaknastu strukturu. Test zasijavanja stanica pokazao je da je biokompozit PLA/BNC pogodan za prihvaćanje i rast humanih stanica, pa je prema tome potencijalno primjenjiv u regenerativnoj medicini i tkivnom inženjerstvu.

Polietilen niske gustoće (LDPE) sintetski je nerazgradljiv polimer koji se najčešće upotrebljava kao ambalažni materijal za pakiranje hrane, međutim njegova nerazgradljivost ima loš utjecaj na okoliš. Razvoj i uporaba biorazgradljivih polimernih materijala ili plastike kao ambalažnog materijala za pakiranje hrane danas je u značajnom porastu. Biopolimeri predstavljaju jednu od najznačajnijih alternativa za razvoj ekološki prihvatljive ambalaže u prehrambenoj industriji zbog njihove biorazgradljivosti. Cilj ovoga rada bio je pripremiti biokompozite na osnovi linearnog polietilena niske gustoće (LDPE), rižinih ljuskica (RLJ) i punila mikro titanijeva dioksida (mTiO2) kako bi se dobili biorazgradljivi biokompoziti s antibakterijskim učinkom, pogodni za primjenu kao ambalažni materijali u prehrambenoj industriji. Biokompoziti su pripremljeni umješavanjem u laboratorijskoj Brabender gnjetilici. Ispitan je utjecaj različitog masenog udjela mTiO2 (w = 0,5, 1,0, 1,5 i 2,0 %) na inhibiciju bakterijske kulture Escherichia coli, Pseudomonas aeruginosa i Bacillus subtilis. Rezultati pokazuju da je mTiO2 inhibirao rast bakterijske kulture Escherichia coli, Pseudomonas aeruginosa i Bacillus subtilis kod masenog udjela mTiO2 od 1,5 i 2,0 % (broj stanica bakterijskih kultura se smanjivao). Rezultati TGA i DSC mjerenja pokazuju prisutnost mTiO2 u biokompozitima.

Latgales lielākais dabas resurss ir meži, jo 40% no tās teritorijas aizņem mežu zemes. Lai gan mežu resursi ir atjaunojams resurss, izturēties pret šo resursu nedrīkst nesaimnieciski, jo meži neatjaunojas tik ātri kā lauksaimniecības kultūraugi, tie ir nozīmīga ekosistēma bioloģiskās daudzveidības saglabāšanai un absorbē būtisku daudzumu CO2. Latgalē, tāpat kā citur Latvijā, vērojama tendence lielu daļu apaļkoksnes eksportēt, nevis izmantot uz vietas produktu ar augstu pievienoto vērtību radīšanai un lielāka ekonomiskā un sociālā labuma gūšanai un ražošanai. Meža nozares kopējais ieguldījums pievienotajā vērtībā valstī ir tikai 5,9%, neraugoties uz to, ka tās īpatsvars IKP (faktiskajās cenās) ir apmēram 62%. Latgalē ir visi priekšnosacījumi, lai meža biomasu izmantotu kā inovatīvu produktu, kas: • nes pēc iespējas lielāku sociālo un ekonomisko labumu valstiskā līmenī,• rada ekodizaina principiem atbilstošu produktu, • ļauj ievērot ilgtspējības principus un racionālu dabas resursu izmantošanu. Šobrīd meža biomasu daudzviet izmanto kurināmā (malkas un šķeldas) ražošanai, kas ir produkts ar zemu pievienoto vērtību. No meža biomasas iespējams iegūt ne tikai klasiskos koksnes produktus (piemēram, būvmateriālus, mēbeles, sadzīves priekšmetus) un kurināmo, bet pat pārtikas izejvielas (piemēram, glikozi, cieti, ksilānu), zivju un dzīvnieku barību, tekstilizstrādājumus un plašu klāstu ķīmisko savienojumu. Tikai no koku mizas iespējams iegūt vairāk nekā 150 vērtīgu ķīmisko savienojumu. Īpaša vērība meža resursu ilgtspējīgai izmantošanai pievērsta tieši pēdējo gadu laikā sakarā ar bioekonomikas idejas un principu aktualizāciju. Šobrīd tiek izstrādāta Latvijas Bioekonomikas stratēģija. Rīgas Tehniskās universitātes Vides aizsardzības un siltuma sistēmu institūtā, noslēdzot līgumu ar AS „Latvijas Valsts meži“, pabeigts meža resursu izmantošanas pētījums. Izpētes mērķis bija izvērtēt valsts iespējas izmantot meža biomasu inovatīvu produktu ar augstu pievienoto vērtību ražošanai un noteikt, kuriem produktiem ir augstākais komercializācijas potenciāls Latvijā. No meža biomasas atlasīti 44 produkti, par kuriem bija pieejama pietiekama informācija, lai analīze būtu pilnvērtīga. Inovatīvie produkti tika sagrupēti un vērtēti pa šādām nozarēm: pārtikas rūpniecība, enerģētikas sektors, tekstilrūpniecība, biokompozīti un biomateriāli un citas nozares. Latgales plānošanas reģionā ir savas kokapstrādes uzņēmējdarbības tradīcijas, tomēr vienlaikus pastāv augsts bezdarba līmenis un liels pašnodarbināto īpatsvars, kas liecina, ka trūkst darba devēju. Latgales Speciālās ekonomiskās zonas likums un infrastruktūras atbalsta mehānismi, loģistikas priekšrocības iezīmē Latgales perspektīvas inovatīvas, uz eksportu orientētas bioekonomikas attīstībai. Pētījums tapis Valsts pētījumu programmā „LATENERGI“.

Dizertační práce se zabývala syntézou a studiem kompozitních materiálů pro potenciální lékařské využití. Teoretická část je zaměřena na biomateriály, zejména na kompozity složené z polyvinylalkoholu a hydroxyapatitu(PVA/HA). Byly připraveny kompozitní membrány složené z polyvinylalkoholu s různým hmotnostním zastoupením hydroxyapatitu - 0%, 10%, 20%, 30%, 40% a 50%. Hydroxyapatit (HA) byl připraven srážecí metodou z hydrogenfosforečnanu amonného a tetrahydrátu dusičnanu vápenatého ve vodném alkalickém prostředí. Vzniklá suspenze se smísila s roztokem polyvinylalkoholu, který byl připraven rozpuštěním ve vodě o teplotě 85° C. Jednotlivé směsi byly odlity do formy a sušeny po dobu 7 dní při teplotě 30 ° C, vzniklé 0,5 mm tenké membrány byly analyzovány ATR-FTIR spektroskopií k identifikaci funkčních skupin v kompozitu, dále byla provedena XRD analýza. Zkouška tahem a TGA měření byly realizovány k určení vlivu HA na mechanické vlastnosti, respektive změnu tepelné odolnosti kompozitů ve srovnání s čistým PVA. Byla provedena zkouška bioaktivity v simulovaném krevním roztoku (SBF) po dobu 2h, 7 a 28 dnů. SEM byla použita k charakterizaci povrchové mikrostruktury biocompositních membrán před a po ponoření do SBF. Na povrchu testovaných membrán vznikla vrstva apatitu, která je charakteristická pro bioaktivní materiály. Bylo zjištěno, že s rostoucím množstvím HA částic docházelo ke vzniku aglomerátů v kompozitu, které vznikly mimo jiné jako důsledek růstu krystalů HA během sušení membrán. Bioaktivita rostla s delším působením SBF na vzorky.

Goal of this diploma thesis was to describe mechanical properties of epoxy resins containing organical fibers and to experimentally evaluate the effect of the fiber length with various concentrations on final mechanical property of composit material. First part of the diploma thesis is dedicated to literature review which describes general properties of fiber composites, materials which they are made of, and mechanical trials. In chapter called Methodics, materials used for experimental research are described. Process of sample preparation and mechanical trials, which were used for the test, are also described there. Last part of the diploma thesis is dedicated to evaluation of results of executed mechanical trials on composites with fiber support of various lengths and concentrations

The aim of this Master’s thesis is to investigate the preparation and structure of nanofibres of inorganic and organic biomaterials. Nanofibres of polycaprolactone, chitosane and their composites with hydroxyapatite particle were prepared by centrifugal force spinning process, which uses centrifugal forces for nanofibres spinning. Designed nanofibres can be used in bone tissue engineering. Experimental activity has started with synthesis of hydroxyapatite nanoparticles and preparation of polymer solutions and composite suspensions at different concentrations. The solutions and the suspensions were characterized by density and viscosity which were changed in dependence on temperature and polymer concentration. The solutions and the suspensions were spun at varying speeds and using two different sizes of collectors. The dependence of spinneret head revolution speed, size of collectors and polymer concentration on nanofibres diameter was studied. Biological activity of polycaprolactone and hydroxyapatite/polycaprolactone nanofibres was tested by means of SBF.

Theoretical part of master's thesis is focused on chemical treatments of natural fibers and their use as reinforcement material in polymer composites. Flax fibers were treated with two different silane coupling agents to improve their adhesion with polymer matrix. Nature of treatment was studied by using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Composites based on both treated and untreated flax fibers were prepared by pultrusion.technique. Mechanical properties and water absorption of prepared composites were evaluated.

Effective biocatalysts for the processes of the esterification of free fatty acids with methanol and technical-grade glycerol were selected and optimal conditions of biocatalysis were established. Principle technological design of free fatty acids esterification with methanol and technical-grade glycerol was developed, which can be applied by biofuel producers and other interested enterprises. The formulations of liquid fuel emulsions containing technical-grade glycerol were developed and principle technological design for the production of these emulsions was suggested. Optimal composition of biofilms containing technical-grade glycerol and deoiled rapeseed cake was determined, on the basis of which the industrial scale production of biodegradable composites can be implemented.
Vykdant tyrimus, parinkti efektyvūs biokatalizatoriai ir nustatytos optimalios laisvųjų riebalų rūgščių esterinimo metanoliu ir techniniu gliceroliu taikant biotechnologinį metodą sąlygos. Sukurtos principinės laisvųjų riebalų rūgščių esterinimo metanoliu ir techniniu gliceroliu technologijos, kurias galėtų diegti biodyzelino gamybos ar kitos suinteresuotos įmonės. Sukurta skystojo kuro emulsijų, į kurių sudėtį įeina techninis glicerolis receptūra, parengta principinė technologija šių emulsijų gamybai. Nustatyta optimali bioskaidžių plėvelių, sudarytų iš techninio glicerolio ir nuriebalintų rapsų išspaudų, formavimo mišinio sudėtis, kuria remiantis biologiškai skalių kompozitų gamyba gali būti diegiama pramonėje.

Истраживање у оквиру докторске дисертације обухвата анализу могућности производње и примене биокомпозитних термоизолационих плоча заснованих на нуспроизводима пољопривредне производње и мицелијума гљиве буковаче као везивног средства. Циљеви истраживања су развој методе за производњу биокомпозитних термоизолационих материјала и утврђивање морфолошких, физичко-хемијских, механичких и хигротермичких својстава биокомпозита. У складу са резултатима истраживања и закључцима да је могуће произвести и користити биокомпозитни термоизолациони материјал заснован на биомаси и мицелијуму гљива изведена је анализа енергетске ефикасности и животног циклуса материјала. Резултати истраживања представљају значајну полазну основу за производњу и даље унапређење биокомпозитних термоизолационих материјала у грађевинарству, са позитивном оценом мицелијума гљива као везивног средства.
Istraživanje u okviru doktorske disertacije obuhvata analizu mogućnosti proizvodnje i primene biokompozitnih termoizolacionih ploča zasnovanih na nusproizvodima poljoprivredne proizvodnje i micelijuma gljive bukovače kao vezivnog sredstva. Ciljevi istraživanja su razvoj metode za proizvodnju biokompozitnih termoizolacionih materijala i utvrđivanje morfoloških, fizičko-hemijskih, mehaničkih i higrotermičkih svojstava biokompozita. U skladu sa rezultatima istraživanja i zaključcima da je moguće proizvesti i koristiti biokompozitni termoizolacioni materijal zasnovan na biomasi i micelijumu gljiva izvedena je analiza energetske efikasnosti i životnog ciklusa materijala. Rezultati istraživanja predstavljaju značajnu polaznu osnovu za proizvodnju i dalje unapređenje biokompozitnih termoizolacionih materijala u građevinarstvu, sa pozitivnom ocenom micelijuma gljiva kao vezivnog sredstva.
Research in the thesis is focused on development and utilisation ofbiocomposite thermal insulation panels based on agricultural biomass andoyster mushroom mycelium as a binding agent. The goals of the research aredevelopment of production method of biocomposite thermal insulation panelsand determination of morphological, physical-chemical, mechanical andhygrothermal properties of the biocomposite. Energy efficiency and life cycleassessment were conducted in accordance with the research results andconclusions that it is possible to manufacture and use the biocompositethermal insulation panels based on biomass and mushroom mycelium. Theresearch results represent significant starting point for manufacturing andfurther improvement of biocomposite thermal insulation panels used in civilengineering and confirm the use of mycelium as a binding agent.

The main goal of the dissertation is to suggest several types of bio-based composites, notably particleboards, made from alternative materials (bio-waste, waste, plants´ residues) as an alternative to the currently produced wooden particleboards. The thesis provides a review and synthesis of the state-of-the-art literature. In the first part the literature is summarized and basic economical and ecological aspects of wood replacements for particleboards by using alternative materials are discussed. Further, mechanical properties data of suggested alternative particleboards are compiled, to give state-of-art insights in alternative particleboards developments. In the state-of-art, the compiled literature data are analysed through Ashby plots and give suggestions on what particleboards properties should be optimized. This evauationhave also proved that particleboards made from plants stalks, wood prunings and other wastes eg. waste tea leaves, peanut hulls, walnut shells could be economically viable alternative for the industry. The second part of this dissertation is concerned with designing and developing particleboards from the alternative resources available in Central Europe: (1) In total, 16 types of particleboards were produced from stalks coming from cup plants, Miscanthus, sunflower and topinambour. These particleboards are specified by standard mechanical tests and the effects of resin content and resin type were studied. Also chemical analysis were performed to determine the cellulose, hemicellulose and lignin contents. Structure of the Miscanthus particleboard were characterized by scanning electron microscopy (SEM). (2) Particleboards were also made and evaluated with different wastes. Particleboard made from BSG (Brewer´s spent grain) were characterized by their mechanical properties, chemical comosition and microscopic structure (SEM). Further, polyethylene terephtalate (PET) waste was added to wooden particleboards. Here, in addition to mechanical properties also microscopic structure and bond failures were analysed using SEM, with air-plasma treated PET particles studied by chemiluminescence and x-ray photoelectron spectroscopy (XPS) for their altered surface chemistry. The final section presents eight particleboard types made from recovered painted wood, as reclaimed from window frames. The effect of painted particles on the physical and mechanical properties were evaluated. With respect to possible applications the most important finding is that all particleboards from plants stalks fulfilled minimal requirements of class P1 in EN 312, which is for general purposes in dry conditions. Furthermore, a three-layer particleboard with spruce surface layers, and a core-layer made from cup-plant would provide a regular appearance of the panel surfaces. Particleboards having 10 % BSG also fulfilled the P1 requirements of EN 312. The particle-particle bonding was found to be a weak point in a entire internal bonding systém. To improve internal bonding experiments with plasma-treated beech wood particles bonded by PVAc was performed. Results have shown a significant improvment of internal bonding due to the plasma treatment. Consequently, the identical plasma treatment was applied to PET particles, which were mixed with wood in the particleboards. Bonding was here improved as well, with the IB higher compared to the untreated control. It was shown that plasma treatment has potential to compensate for declined IB of particleboards using alternative sources. In final part of this thesis, particleboards from reclaimed wood from painted window frames were produced. Results have shown that particleboards using painted-reclaimed wood as well as cleaned reclaimed wood deliver a performance comparable with regular wooden particleboards, as well as reduced thickness swelling.

The theoretical part of this doctoral thesis provides a comprehensive overview on the topic of preparation and subsequent utilization of magnetic derivatives of biological materials for xenobiotic separation from water. Main attention is paid to magnetic modification of waste materials and by-products originating from agricultural and food industry, which represent widely available and low-cost materials, and also to magnetic modification of microbial cells. In addition to the description of magnetic particle preparation and individual developed techniques of magnetic modification, a brief characterization of selected pollutants and a detailed table overview on utilization of magnetically responsive biomaterials for biosorption of organic dyes, heavy metals, pharmaceutical and personal care products together with ubiquitous industrial endocrine disruptors and also of crude oil derivatives is presented. Experimental part of this thesis is focused on the preparation and optimization of new types of magnetic materials. Emphasis is placed on the employment of simple, fast and simultaneously low-cost magnetic modification techniques (e.g., postmagnetization using microwave-synthesized magnetic iron oxides or one-step modification by magnetic fluids). Selected plant materials (barley and rye straw) were chemically modified to significantly (up to five-times) increase the maximum adsorption capacities for tested dyes. All prepared biomaterials exhibited a great magnetic response and simultaneously relatively high adsorption capacity for selected xenobiotics under experimental conditions used. Factors substantially affecting adsorption process, such as pH, initial concentration, incubation time or temperature were also studied. Adsorption equilibrium data were assessed using Langmuir, Freundlich or Sips isotherm models. Experimental data from time dependence study were analyzed by chosen kinetic models, namely the pseudo-first-order and pseudo-second-order ones and by intraparticle diffusion model. Thermodynamic parameters (Gibbs free energy, enthalpy and entropy) describing the nature of adsorption were also included in study.