Une mousse de PA66 peut être obtenue à partir de granulés de PA66 expansibles en utilisant un procédé de transformation classique des polymères. Les granulés expansibles de PA66 sont préparés par extrusion bi-vis corotative en mélangeant le PA66 et un agent moussant spécifique au PA66 qui contient des fonctions isocyanate bloquées. Le moussage a lieu dans une seconde étape (extrusion ou moulage par injection) à une température supérieure à la température de préparation des granulés expansibles et suffisamment élevée pour libérer les fonctions isocyanate. Une fois libérées, les fonctions isocyanate réagissent avec les groupements terminaux acide carboxylique du PA66 (modification de la masse molaire du PA66) et l'eau présente dans le milieu réactionnel ce qui génère du CO2. L’objectif de cette thèse était de montrer comment contrôler la morphologie des mousses par le contrôle de la cinétique de réaction chimique, de la rhéologie et des paramètres d’injection. Nous avons montré qu’une augmentation du taux d’agent moussant, de la température ou du temps de séjour entraîne une augmentation de la quantité de CO2 générée. De plus, le comportement rhéologique du système PA66m/CO2 dissous, est une fonction complexe de l’état d’avancement des réactions c'est-à-dire de la quantité de CO2 générée et de la modification de la structure du PA66 (augmentation de la masse molaire): il peut être plus visqueux ou moins visqueux que le PA66 standard. Enfin, des tests de moussage en moulage par injection ont été réalisés: des mousses homogènes dont les tailles de bulles étaient de l’ordre de quelques centaines de microns et les taux de moussage compris entre 10 et 50% ont été obtenues. / PA66 foam can be obtained from expandable PA66 pellet using classical polymer processing process. The expandable PA66 pellets are prepared by mixing PA66 and a specific foaming agent which contains blocked isocyanate (NCO) moieties in twin screw extrusion. Foaming takes place in a second step (extrusion or injection molding) at a temperature higher than the temperature for the preparation of expandable beads and high enough to release the isocyanate moieties. Once released, the isocyanate moieties react with the carboxylic acid end groups of PA66 (modification of the molecular weight of PA66) and water contained in the reaction medium, which generates CO2. The aim of this PhD thesis was to be able to control the morphology of the foam by controlling the chemical reaction kinetics, rheology and injection molding parameters. We have shown that an increase of foaming agent content, temperature or residence time leads to an increase of CO2 release. In addition, the rheological behavior of the system PA66m/CO2 dissolved, is a complex function of foaming reactions progress which means, the amount of CO2 generated and the modification of PA66 structure (increase molar mass): it may be more or less viscous than standard PA66. Finally, trials of foaming by injection molding were performed: homogeneous foams with bubble sizes of the order of a few hundred microns and foaming rate between 10 and 50% were obtained.

This thesis presents the study of nanocomposites based on immiscible polymer blend of polycarbonate and acrylonitrile-butadiene-styrene (PC/ABS) filled with multi-walled carbon nanotubes (MWCNT). The aim is to achieve an improvement of mechanical properties and electrical conductivity of the nanocomposites. In an initial stage, a twin-screw extruder was used to obtain nanocomposites by melt compounding. Three methods of carbon nanotubes addition were studied: direct addition, dilution from a masterbatch and feeding of MWCNT suspension in ethanol. For each method, the influence of nanofiller content and processing parameters on morphology and final properties of the nanocomposite was analyzed. Furthermore, the influence of two types of carbon nanotubes modifications was studied: covalent modification by surface-oxidation (MWCNT-COOH) and non-covalent modification by an addition of surfactant promoting the nanofiller-matrix interactions. A good dispersion of the MWCNT was obtained for masterbatch dilution and suspension feeding. Both methods showed preferential localization of carbon nanotubes in polycarbonate phase (PC). Samples processed by masterbatch dilution showed the 30 % increase of rigidity and a decrease of ductility of PC/ABS for 0.5 wt. % MWCNT. Electrical conductivity was influenced by processing temperature and carbon nanotubes type. The percolation threshold value was 2.0 wt. % for pristine MWCNT and 1.5 wt. % for modified MWCNT-COOH. Better balance of mechanical properties and electrical conductivity was achieved in the samples obtained by the masterbatch route. These properties were studied in a subsequent phase, when the extruded nanocomposite was injection molded in order to obtain a defined geometry. / Wegrzyn, M. (2014). Nanocomposites of Multiphase Polymer Blend Reinforced with Carbon Nanotubes: Processing and Characterization [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36869 / TESIS

This diploma theses raises the issue of internal tension in two-component outer lense, which are made by injection of polycarbonate. The theses gives a more detail view on treatment of the lenses in heating ovens. Heating ovens have been used for decreasing the internal tension in lenses. The subject of the experiment is to determine the influences of the adjustable parameters of the heating oven. The Experiment will be taken by DoE method. The influence of the adjustable parameters is researched and compared among the two types of outer lense with different type of design.

This diploma thesis submits a proposal of technology design manufacturing threaded plastic ends. In the first part it deals with literary studies of plastics and plastic injection molding. In the second part is the design of an injection form for the specified component. Part of the practical part is also the right choice of material and the injection mold, which was designed based on the calculations of technological parameters. In the conclusion of this thesis is technical economic evaluation.

The meaning of the diploma thesis is to create a new mold plunger for injection mold using a suitable method according to the original mold plunger. The final mold part should meet the required surface parameters. The work is focused on the analysis of the original mold plunger and the experimental verification of suitable methods of production of the equivalent mold plunger.

The aim of the thesis is to determine change of mechanical properties of three types of damp polymeric materials (polyamides) depending on the water content inside material. Before testing, specimens of all three types of materials were placed inside the air conditioning chambers until equilibrium (conditioned) state was reached when the specimens received the maximum possible amount of water from the environment. A total of three conditioning levels were set, representing besides the standard level of conditioning both extreme states like state when the material was fully dried and the state where the material content the largest possible amount of water. With the increasing content of water bound in material, there is a characteristic change in the mechanical properties of the material, such as a decrease in strength and modulus of elasticity and an increase in toughness and ductility. To examine material properties change, tensile and Charpy impact tests were performed, Charpy impact tests were performed for both specimens with and without a notch. Besides changes in mechanical properties, the rate of water absorption was also observed depending on the materials and its filling.

The project elaborated design of optimization venting of molds exhibiting bubbles or low quality weld lines. Based on a literature study of the injection mold venting, the use of vacuum venting, namely the VACUUMJET system of the Spanish CUMSA manufacturer, has been proposed. The experiments proved the elimination of bubbles in the part and the marked improvement of visual quality of the weld lines. The effect on the closing force was not confirmed. The use of the system is more economical for larger batches production, or when high quality parts are required that allow price increasing.

The paper target is design of a conceptual solution of a two-component light-guide with the use of available materials, commonly used for the production of headlamp components, emphasizing the simplicity of the whole solution. The result will be in production of a prototype and the subsequent testing of its functional parameters using standard equipment for the measurement of photometric quantities.

The automotive thermostat currently contributes significantly to the potential to reduce the output of the exhaust gases. The heart of the modern thermostat is the ball valve assembly which also deals with this master‘s thesis. First of all the principles of the quality of the automotive thermostat are described with the choice of further deeper examined properties. The manufacturing process of a ball element and PTFE sealing ring is described. Subsequently the problem of increased production of nonconforming products in production is studied focusing on the surface texture of teflon ring and shape analysis of the ball element. Finally a recommendation for practice with regard to the reduction of additional costs associated with poorly manufactured part is created and further action on this issue is recommended.

The aim of this thesis is design of technology project for plastic manufacturing. The theoretical part is focused on the characteristics of plastics and plastics production, especially for injection molding of thermoplastics. In the practical part are presented the calculations needed to choice of the injection molding machines and the capacity calculations to determine consumption of granulate and productivity of injection molding machines. Part of this thesis is a list of optimal machinery, including the required peripherals and handling devices complying with the current requirements of a modern plastic manufacturing. The result of this thesis is an economic evaluation of investment costs of machinery for small and medium-sized plastic manufacturing.