|
|
Study of conditions influence on the rate of crack propagation in HDPE
Patzelt, Petr ; Kučera, Jaroslav (referee) ; Petrůj, Jaroslav (advisor)
Theoretical part of the thesis is aimed on the summary of material and testing parameters that influence SCG process and also the duration of FNCT test. The experimental part deals with the comparison of time to crack between two used surfactants – 2% Arkopal N110 and 10% sodium dodecylbenzenesulfonate. The temperature during the experiments was 80 °C. The acceleration of the process influenced by solution of sodium dodcelbenzenesulfonate was many times higher against solution of Arkopal. There were tested several HDPE and PP specimens to prove this phenomenon. HDPE specimens used – VB85, VL 20N, PL 10 that were made in UNIPETROL RPA and some other competitive materials were used. PP specimens were developed in labs of Polymer Institute Brno. In additional, another experimental part focuses on evolving the math definition of curves measured within FNCT tests and it is still in progress.
|
|
| |
|
|
Study of Relation between HDPE Internal Structure and Its Cut Growth Resistance SCG (Slow Crack Growth)
Chladil, Martin ; Žídek, Jan (referee) ; Petrůj, Jaroslav (advisor)
This thesis deals with the relation between structure and resistance to failure by the mechanism of slow crack growth (SCG) in HDPE. In the theoretical part there are summarized previously acquired knowledge about the production of PE and about the relation between structure and resistance to failure by the SCG mechanism. In the experimental part, three samples of HDPE with the same melt index MI and the same content of copolymer 1- hexene were synthesized by using three chromium catalysts commonly used for polymerization in industry. There samples were analyzed by GPC-IR-MALS and TREF in order to determine the distribution of side chain branches. The results were discussed with respect to the time to failure FNCT.
|
|
|
Temperature and Time Influence on Crystalline and Amorphous Phase Content in Polypropylene
Vilč, Ladislav ; Petrůj, Jaroslav (referee) ; Čermák,, Roman (referee) ; Kratochvíla, Jan (advisor)
is is a study of the relationship between structure, mechanical properties and relaxing behavior of the polypropylene. The structure was evaluated by the quantity the solid phase content (SPC). This was defined as mathematical result of free induction decay (FID) signal from pulsed 1H-NMR. The solid phase content is a quite new structural parameter representing the quantity for description of semi-crystalline polymers. Whereas pulsed 1H-NMR is non-destructive, accurate and repeatable, it becomes a unique tool for a description of mechanical, structural, physical-mechanical changes of polypropylene within the time and temperature. Particularly, this method registers the small changes in the time-dependant shipments during secondary crystallization with small structure changes.
|
|
|
Waste Recycling Possibilities of Rigid PU Foams from the Production of KingSpan CZ
Figalla, Silvestr ; Kučera, František (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the bachelor thesis evaluates methods and trends of recycling polyurethane materials with the emphasis on rigid polyurethane foams used as thermo isolation building material. The experimental part is focused on glycerol process verification as an alcoholization agent in the regenerative process of polyol, together with perspective microwave heating of reaction mixture. The final part of the work suggests further steps in the development of above mentioned process with the aim of its transforming into technical practice.
|
|
|
The Study of Polyolefins Photochloration
Kučera, Vladimír ; Tocháček, Jiří (referee) ; Petrůj, Jaroslav (advisor)
This Master´s thesis deals with heterogeneous photochlorination of polyolefins and especially with the photochlorination of polypropylene itself. In the theoretical part the available information about properties, manufactory and application of chlorinated polyolefins, specifically polyethylene and polypropylene, is provided. The basic principles of the photochemistry are described, which are further applied to the issue of photochemistry chain reactions and photochemical halogenations, mainly photochlorinations. The practical part includes design and realization of few types of equipment for the heterogeneous photochlorination of polypropylene done at low temperatures (to 50° C) by gaseous chlorine in bulk or chlorine suspended in suspension of PP in CCl4. Series of chlorination was accomplished, which was varied in the type of PP, in the way of dosage Cl2 and in the period of high pressure mercury lamp irradiation (1–90 minutes). The chlorine content in prepared samples was determined by the gravimetry with ATR-FTIR spectroscopy, as well as by the Shöniger combustion method. Their accuracies were than compared. The chlorine content dependence on the period of chlorination and on the porosity of initial PP was established.
|
|
|
Imidation of cyclic anhydrides and modified polyolefins
Šimonek, Michal ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The main focus of the presented bachelor’s thesis is on the reaction pathway that leads to the formation of cyclic imides and utilizing imidation as a way to modify polyolefins. The theoretical part serves as a summary of relevant information concerning the formation of imides, functionalization of polyolefins via radical-induced grafting, and exploitation of reactions between anhydride-modified polyolefins and various amines. The specificity of amic acid formation was tested via reactions of succinic acid and ammonia in different molar ratios. Suitability of succinamic acid and its ammonium salt to give succinimide was evaluated. Similarly, N-substituted succinamic acid and succinimide were prepared from commercial amine, Elastamine RE1-2007, and succinic acid. Imide modified polyolefins were prepared firstly by a reaction in a solution of toluene, secondly in the melt in Brabender laboratory kneader at 60 and 120 rpm respectively, reaction temperature of 190 °C and reaction time of 16 minutes. The presence of expected groups in all samples was determined by FT-IR spectrometry. Modified polyolefins from the reaction in a solution were analysed by DSC and TGA to determine suitable reaction temperature for experiments in the melt. Kneader torque traces were examined to characterize mixing during reactions in the melt state.
|
|
|
Functionalization of polyolefins by grafting
Paulenka, Igor ; Petruš, Josef (referee) ; Petrůj, Jaroslav (advisor)
The theoretical part of the diploma thesis is focused on the funcionalization of polyolefins in order to accelerate their degradation and to increase their carbon content from renewable resources with focus on hydroxyacids. The experimental part is focused on preparing samples and studying the properties of the polypropylene and polyethylene blends with the polylactide with different contents of the initiator and the maleic anhydride. Samples were evaluated by determining the degree of conversion maleic anhydride, differential scanning calorimetry, infrared spectroscopy, melt flow index and mechanical properties.
|
|
|
The Study of Ethyllactate Synthesis from Lactic Acide Salts
Hlavatá, Daniela ; Figalla, Silvestr (referee) ; Petrůj, Jaroslav (advisor)
This diploma thesis deals with senthesis of lactic acid ethyl ester from slats of lactic acid. The literature review has been processed in the theoretical part of the diploma thesis. It is focused on manufacturing technologies of lactic acid esters, mainly on ethyl lactate by conventional and non-conventional ways of producing. Also the literature review involves producing of lactic acid and slats of lactic acid by fermentation because subsequently is possible produce ethyl lactate from that two substances. The laboratory apparatus for preparation of ethyl lactate and methyl lactate has been designed, realized and verificated function of it in the experimental part. There were carried out laboratory experimnets for production ethyl lactate and methyl lactate in this apparaturs.
|
|
|
Direct Synthesis of High-Molecular Polymers of Lactic Acid
Mikulík, David ; Kupka, Vojtěch (referee) ; Petrůj, Jaroslav (advisor)
This master thesis deals with the direct synthesis of polymers from lactic acid. The theoretical part focuses on both natural and synthetic ways of production the lactic acid monomer, their advantages and properties. Furthermore, the theoretical part focuses on the synthesis of poly(lactic acid) (PLA) from lactide, and direct polycondensation from lactic acid discussing about influences of catalysts, co-catalysts as well as chain extenders. The experimental part focuses on the synthesis of PLA polymers and co-polymers wherein investigates suitable catalysts, reaction medium for azeotropic dehydration and co-catalyst influence on products. Thermal and analytical analysis of PLA polymers are mentioned at the end of the experimental part.
|
guest ::
RSS feed.