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Structural and morphological characterization of polyamide buckles
Kubíčková, Eva ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
The work deals with structrural and morphological characterization of polyamide buckles used to fasten webbins. The buckles were produced in five different years, a few of those produced in 2000 and 2004 were broken. The aime is to determine the type of polyamide and the cause of fracture of the buckles during using. The buckles were characterized in terms of structure and composition by Fourier-transform infrared spectroscopy in a mode of attenuated total reflaction, differential scanning calorimetry, thermogravimetry and X-ray diffraction. The buckles were made of polyamide 12. The broken buckles showed higher melting point, lower thermal stability and, in addition to modification it also contains modification, which is more fragile and probably represents the cause of fracture.
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Growth of metastable fcc Fe thin films on Cu/Si(100) substrates
Horký, Michal ; Cháb, Vladimír (referee) ; Urbánek, Michal (advisor)
This diploma thesis deals with the preparation of epitaxially grown metastable paramagnetic Fe films alloyed by Ni on Cu/Si(100) substrates at RT. Molecular beam epitaxy of Cu(100) buffer layer was performed on H-Si(100) native SiO2 free samples treated by etching in HF or thermal treatment. The epitaxially grown Cu layers with thickness ranging from 50 up to 130 nm serves as suitable substrate for the deposition of 44-ML-thick paramagnetic Fe78Ni22. The film growth was taking place in CO atmosphere and as well as Ni it led to paramagnetic film stabilization. The structural and magnetic ion-beam-induced transformation of desired Fe-Ni structure was performed and propeties of irradiated films were characterized afterwards by MOKE. Then some specific patterns on Si(100) by e-beam litography were fabricated and they served as suitable matrix for Cu(100) buffer layer and paramagnetic Fe. Prepared Si(100), globally and locally deposited metal films were examined by LEED, XPS, AFM, AES, SEM a STM. The recorded results showed the possibility of paramagnetic films preparation on H-Si(100) where it was possible to make ferromagnetic patterns on paramagnetic background by irradiation of specific ion dose.
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Growth of metastable fcc Fe thin films on Cu/Si(100) substrates
Horký, Michal ; Cháb, Vladimír (referee) ; Urbánek, Michal (advisor)
This diploma thesis deals with the preparation of epitaxially grown metastable paramagnetic Fe films alloyed by Ni on Cu/Si(100) substrates at RT. Molecular beam epitaxy of Cu(100) buffer layer was performed on H-Si(100) native SiO2 free samples treated by etching in HF or thermal treatment. The epitaxially grown Cu layers with thickness ranging from 50 up to 130 nm serves as suitable substrate for the deposition of 44-ML-thick paramagnetic Fe78Ni22. The film growth was taking place in CO atmosphere and as well as Ni it led to paramagnetic film stabilization. The structural and magnetic ion-beam-induced transformation of desired Fe-Ni structure was performed and propeties of irradiated films were characterized afterwards by MOKE. Then some specific patterns on Si(100) by e-beam litography were fabricated and they served as suitable matrix for Cu(100) buffer layer and paramagnetic Fe. Prepared Si(100), globally and locally deposited metal films were examined by LEED, XPS, AFM, AES, SEM a STM. The recorded results showed the possibility of paramagnetic films preparation on H-Si(100) where it was possible to make ferromagnetic patterns on paramagnetic background by irradiation of specific ion dose.
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Structural and morphological characterization of polyamide buckles
Kubíčková, Eva ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
The work deals with structrural and morphological characterization of polyamide buckles used to fasten webbins. The buckles were produced in five different years, a few of those produced in 2000 and 2004 were broken. The aime is to determine the type of polyamide and the cause of fracture of the buckles during using. The buckles were characterized in terms of structure and composition by Fourier-transform infrared spectroscopy in a mode of attenuated total reflaction, differential scanning calorimetry, thermogravimetry and X-ray diffraction. The buckles were made of polyamide 12. The broken buckles showed higher melting point, lower thermal stability and, in addition to modification it also contains modification, which is more fragile and probably represents the cause of fracture.
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CHARACTERIZATION OF METALLOCENE-MADE POLYPROPYLENE WITH NARROW DISTRIBUTION OF MOLECULAR WEIGHT
Fojtlová, Lucie ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Metallocene based polypropylene (mPP) with very narrow distribution of molecular weight was peroxide-degraded to materials of four different molecular weights including the original mPP labeled MET1–MET3 and MET0, respectively. Double bonds formed after peroxide-degradation was proved on material surfaces by FTIR-ATR (attenuated total reflection of Fourier-transformed infrared spectroscopy). The decreasing molecular weight led to gradual decrease of the tensile strength, tensile modulus as well as the strain and to the decrease of the temperature of thermal decomposition. Confocal laser scanning microscopy (CLSM) of chemically etched surfaces of MET0–MET3 revealed supramolecular structure of commonly occurred structure (radical spherulites) but also supramolecular structure of form (sheaf-like structure). The latter was proved by XRD together with the fact that the content of form decreases with decreasing molecular weight. The mentioned structure differences were not visible on DSC curves because the amount of structure was small and melting temperature, temperature of crystallization and the degree of crystallinity remained the same for all four types of mPP. The structure of the original materials was also characterized after isothermal crystallization performed on differential scanning calorimetry (DSC) and under polarizing optical microscope (POM). The first was performed at 120–126 °C and the latter at 130 °C (Tic). The materials obtained on DSC always contained the structure and its amount increased with increasing Tic whereas higher content of form was always in MET0 with respect to MET3. The structure was proved by XRD and also by DSC heating run followed immediately after the isothermal process. The latter revealed two endotherms belonging to melting of and forms. The presence of form was on the surfaces proved by CLSM. The formation of structure was in-situ observed on POM and the amount of it decreased with decreasing molecular weight. The spherulite growth rate increased with decreasing molecular weight whereas the rate of crystalline portion expressed as half-time of crystallization decreased with decreasing molecular weight.
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