Národní úložiště šedé literatury Nalezeno 2 záznamů.  Hledání trvalo 0.00 vteřin. 
Shear strength of the fiber-reinforced polymer composite
Jurko, Michal ; Knob, Antonín (oponent) ; Čech, Vladimír (vedoucí práce)
The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.
The study of sulfate depletion in cement binders
Jurko, Michal ; Švec, Jiří (oponent) ; Novotný, Radoslav (vedoucí práce)
This bachelor thesis deals with the study of sulfate depletion in cement binders. Basic knowledge about cement binders is summarised at the beginning of the theoretical part. The theoretical part goes on to describe the hydration of Portland cement (PC) and to briefly describe the influence of different types of milling on PC particle size. In the experimental part, PC fractions of various average particle sizes were prepared on a planetary ball mill for wet conditions. On the prepared cement, their hydration was studied using isothermal calorimetry; especially sulfate depletion, portlandite precipitation, heat flow rate and induction period interval. n the thesis were also used analyzes for autogenous shrinkage, XRD and STA. The input raw materials are cement CEM I 42,5 R (grey, Českomoravský cement, a.s. – Mokrá, Czech Republic) and sulfate-resistant cement CEM I 52,5 R (white, Aalborg Portland, a.s. – Aalborg, Denmark). On the basis of the results analysis, a proposal was made to correct the presence of sulfate ions by adding gypsum in these cements. In the case of CEM I 52,5 R the correction is recommended and in the case of CEM I 42,5 R the correction is necessary.

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