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Posouzení využitelnosti vybraných listnatých dřev pro výrobu kompozitu na bázi dřeva
Kašpařík, Matěj
The bachelor thesis deals with the issue of the possibility of replacing spruce wood in the production of OSB with hornbeam and birch wood. The purpose of the thesis is to compare selected physical and mechanical properties of OSB made of these woods with standardized properties of OSB. In the first part, the origin, characteristics and current use of OSB are presented. The second part deals with the material and methodology of all the tests performed. The following properties of the boards were investigated: moisture content, flexural strength and elastic limit, density profile, swelling, delamination and shear strength of the glued joint. In the third part of the paper, the results of the tests and their comparison with the standard requirements for OSB are presented, followed by a summary and discussion.
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Posouzení využitelnosti vybraných listnatých dřev pro výrobu kompozitu na bázi dřeva
Mišičák, Patrik
The bachelor thesis deals with the assessment of the usability of alder and aspen wood for the production of wood-based composite, specifically the production of OSB. It uses the experimental analysis carried out to evaluate the applicability for sheating materials of timber frame structures. First section reviews particleboard with a focus on OSB. It summarises the importance, use and production of OSB panels and focuses on alternative raw material types for the production of wood-based composites. Describes the various technological processes involved in the production of OSB. The second part focuses on the individual production operations and shows the measurement procedures carried out. It also illustrates the determined data and the statistical methods applied to them. Based on the statistically processed data of selected physical and mechanical properties of the manufactured boards, it compares and evaluates the determined values with the requirements specified in standard ČSN EN 300, corresponding to the given application.
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Vliv tepelné a chemické modifikace na sorpční, difuzní a hygroexpazní vlastnosti dřeva
Imramovský, Pavel
This thesis dealed with the influence of heat and chemical modification on sorption, diffusion and hygroexpansion properties of wood. To this aim, a thermal modification of European beechwood was carried out at temperatures (180 °C, 200 °C, 220 °C) in the special modified chamber of Katres. Furthermore, chemical modification was required on individual samples using acetic acid anhydride. The individual samples had to be sliced in radial and tangential directions using microtoma. A dynamic vapour sorption (DVS) device was used to determine the sorption and diffuse properties of all these beech slices as well as the reference unmodified sample. In addition, dynamic swelling was determined for all groups studied in radial and tangential directions. In order to determine the rate of swelling, sample sizes were measured using a scaler in specified directions before and after the 24-hour period in the water. The results indicated that both heat- and chemically-treated beechwood scored better against moisture than reference untreated samples. The diffusion coefficient in the radial direction was also higher than in the tangential direction, which corresponds to the professional literature. The results indicate that heat- and chemically-treated beechwood resisted better moisture than the reference untreated samples. Within swelling, direction plays a large role, as measurements in the tangential direction are nearly twice as high as the radial. The possibilities of using modified wood in construction as well as from the perspective of the researched characteristic were considered. The statistics were performed in the ANOVA program.
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Characterization of Mechanical Properties of semi-IPN Hydrogels Based on Poly(vinylalcohol)
Přibyl, Jiří ; Pekař, Miloslav (referee) ; Kalina, Michal (advisor)
This diploma thesis deals with the issue of mechanical properties of semi-IPN hydrogels based on poly(vinylacohol). The prepared poly(vinylalcohol) hydrogels were modified by the addition of sodium alginate, dextran, DEAE-dextran, chitosan, and poly(ethyleneglycol). The mechanical properties were studied by various methods, such as the oscillatory amplitude rheological test, dynamic mechanical analysis, swelling experiments and drying characteristics. Microcalorimetry was used to study the interactions between poly(vinylalcohol) and biopolymers in solution using the ITC method and the morphology of prepared hydrogels was visualized using cryo-SEM. The main concept for semi-IPN hydrogels is that there is minimal influence on the mechanical properties but leads to the modification of the binding sites present in the hydrogel structure, which has a high potential in transport properties. From the experimental results, the effects of each biopolymer on the mechanical properties were determined. The obtained results showed that the additions of biopolymers do not have a significant impact on the mechanical properties of PVAl hydrogels, but in the case of swelling experiments, there is a significant influence of the number of freezing/thawing cycles, ionic strength of the environment, and the used biopolymer.
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Innovative wood-based materials
Buriánek, Vlastimil ; Brožovský, Jiří (referee) ; Vaněrek, Jan (advisor)
This bachelor’s thesis deals with the issue of optimizing the modification process for plywood boards. Optimization consists mainly in evaluating different densification methods with different parameters of plasticization and stabilization. Psychical parameters (bulk density, swelling, water absorption) and strength parameters (bending strength, modulus of elasticity) of modified plates were chosen for the evaluation parameters. The practical part involved the verification of two thickening treatments on birch plywood.
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Structural and transport properties of hybrid hydrogels with application utilization
Zhurauliova, Darya ; Pekař, Miloslav (referee) ; Smilek, Jiří (advisor)
The presented diploma thesis deals with the preparation and subsequent characterization of structural and transport properties of hybrid hydrogels based on polyvinyl alcohol and sodium alginate concerning their application potential. The thesis aims to study the current state of the solved issue on the topic of characterization of structural and transport (release) properties of hybrid hydrogels about their use in various branches of human activity and also based on literature research to propose and optimize a suitable preparation procedure and to carry out a series of experiments for their characterization. With regard to the literature research, suitable polymers capable of gelation, such as polyvinyl alcohol (PVA) and natural polysaccharide – sodium alginate, were selected for the preparation of hydrogels. The preparation of this hybrid network involved the physical cross-linking of PVA by freezing and thawing and ionic cross-linking of sodium alginate with calcium ions. By combining these polymers, viscoelastic, swelling and transport properties were determined by using physicochemical methods. Rheological measurements were performed to study the mechanical properties - specifically oscillation and amplitude tests. The structural properties of hydrogels (or xerogels) were determined, by scanning electron microscopy. The transport (release) properties of gel systems were determined by diffusion experiments with the UV-VIS spectrometry detection method, in which an organic dye (methylene blue) was used as a model probe. Another aim of this diploma thesis is to modify the internal structure of hybrid hydrogels with suitable reagents, ie., lecithin. The presence of lecithin in the hybrid hydrogel three-dimensional network serves as a model of the phospholipid bilayer, forming the cell membrane or occurring in tissues, and thus has a significant effect on rheological and transport properties. Physicochemical methods also determined the mechanical, swelling and transport properties of hybrid hydrogels with the addition of lecithin. The conclusion of this work is a summary of measured data to provide a comprehensive overview of this issue. The results suggest that the presence of sodium alginate in the PVA structure reduces the mechanical properties, although the presence of lecithin increases the strength of the hybrid hydrogels. However, by comparing all measurement results, it is possible to determine that sodium alginate, resp. lecithin affects the properties and structure of the hydrogel, which makes it possible to correct the properties of hybrid gel systems according to the required applications.
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Influence of formulation factors on the characteristics of terbinafine loaded nanoparticles.
Barák, Vlastimil ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
CHARLES UNIVERSITY FACULTY OF PHARMACY IN HRADEC KRÁLOVÉ DEPARTMENT OF PHARMACEUTICAL TECHNOLOGY Author: Vlastimil Barák Title of Diploma thesis The influence of formulation factors on the characteristics of terbinafine loaded nanoparticles Supervisor: PharmDr. Eva Šnejdrová, Ph.D. Consultant: Mgr. Juraj Martiška The diploma thesis is focused on biodegradable polymer nanoparticles loaded by terbinafine based on the copolymer of glycolic and lactic acid branched on polyacrylic acid. The nanoprecipitation method was employed, and the influence of formulation factors on nanoparticle characteristics was studied. The following formulation factors were the concentration of the polymer, the amount of terbinafine, and the concentration of surfactant. Nanoparticles of 120 nm to 300 nm were obtained depending on the preparation conditions. The nanoparticle polydispersity was in all cases from 0.080 to 0.230. The prepared nanoparticles were stable, as evidenced by zeta potential values above 38 mV. A positive zeta potential is desirable for dermal and mucosal adhesion in the topical and ocular application of nanoparticles with terbinafine. The amount of polymer used to form nanoparticles has the greatest effect on particle size. With increasing polyester concentration in the internal phase, the size of the...
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Terbinafine-loaded biodegradable polymeric systems for topical administration
Pokorná, Tereza ; Šnejdrová, Eva (advisor) ; Dittrich, Milan (referee)
CHARLES UNIVERSITY FACULTY OF PHARMACY IN HRADEC KRÁLOVÉ DEPARTMENT OF PHARMACEUTICAL TECHNOLOGY Author: Tereza Pokorná Title of Diploma thesis Terbinafine-loaded biodegradable polymeric systems for topical administration Supervisor: PharmDr. Eva Šnejdrová, Ph.D. In the diploma thesis the released properties of solid dispersions with terbinafine, based on polyesters of D,L-lactic acid and glycol acid, branched with pentaerythritol and tripentaerythritol are studied. The theoretical part deals with solid dispersions, their classification and methods of preparation, methods of drug dissolution testing, properties, effect, use of terbinafine and preparations containing terbinafine. In the experimental part, solid dispersions were prepared by the melting method. The drug was incorporated into the polyester in the form of a hydrochloride or a base in a concentration of 10 % or 20 %. Some systems were plasticized with 30% triethyl citrate. Thin layers were formulated from solid dispersions, and drug dissolution tests were performed on phosphate buffer pH 7.4 at 37 řC. Assay of terbinafine released was performed spectrophotometrically at 223 nm and ultra-high performance liquid chromatography. Based on the results of this diploma thesis, it can be clearly stated that the suitable carrier of terbinafine...
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