20.500.12556/RUL-139412 Vpliv hitrosti ohlajanja na reološke, termične in morfološke lastnosti polietilenov nizke oziroma visoke gostote The effect of cooling rate on rheological, thermal and morphological properties of low- and high-density polyethylene Izdelke iz polimernih materialov izdelujemo z različnimi tehnološkimi procesi, kot so brizganje, ekstrudiranje, termoformiranje in pihanje. Končne lastnosti izdelka, proizvedenega iz delno kristaliničnih polimerov, so v veliki meri odvisne od notranje strukture, ki se formira med predelovalnim procesom. Nanjo vplivamo s številnimi parametri. Eden pomembnejših je hitrost, s katero oblikovan izdelek shladimo. V eksperimentalnem delu magistrske naloge smo raziskovali, kako hitrost ohlajanja vpliva na reološke, termične in morfološke lastnosti polietilena nizke gostote (LDPE) in polietilena visoke gostote (HDPE). Za izbrana materiala smo s pomočjo diferenčne dinamične kalorimetrije (DSC) določili vpliv različnih hitrosti ohlajanja na temperature faznih sprememb in izračunali delež kristalne strukture za posamezno hitrost ohlajanja. Pri enakih temperaturnih pogojih smo izvedli reološke meritve, ki so nam pomagale razumeti vpliv hitrosti temperaturnih sprememb na reološke lastnosti. Z optičnim polarizacijskim mikroskopom pa smo opazovali, kako se pri tem spreminja morfologija materialov. Plastic products are prepared by various technological processes, such as injection moulding, extrusion, thermoforming and blowing. Final properties of the semi-crystalline polymer product largely depend on the internal structure formed during the manufacturing process. The formation of the internal crystalline structure depends on various parameters. One of the most important ones is the cooling rate. In the experimental part of the master's thesis, the research was focused on the effect of cooling rate on the rheological, thermal and morphological properties of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Differential scanning calorimetry (DSC) was used to determine the influence of different cooling rates on phase transitions temperatures. Moreover, for each cooling rate, the percentage of the crystal structure – degree of crystallinity was calculated. Rheological measurements were performed at the same temperature conditions and the results were used to understand the impact of the rate of temperature changes on rheological properties. Finally, the changes in morphology were followed by using an optical polarizing microscope. LDPE HDPE diferencialna dinamična kalorimetrija (DSC) reologija kristaliničnost viskoznost morfologija LDPE HDPE differential scanning calorimetry (DSC) rheology crystallinity viscosity morphology true false false [P. Tomšič] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2022-09-02 08:30:30 2022-09-02 08:30:33 2023-11-14 12:48:15 0000-00-00 00:00:00 2022 0 Ljubljana 0 XX, [70] str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 536.54:678.675(043.2) 243985 120246019 17445.pdf 17445.pdf 1 6860E559C5F1805DE6DB6BD66B2DA02F 9a2b0ff30d1db386242c81c0c3d5d6a1a4cea8bf30df3f429f310edd6abb205d b535e1be-2a88-11ed-92af-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=159973 Fakulteta za strojništvo 0 0 0