20.500.12556/RUL-119354 Tokovne lastnosti kompozitov polipropilena z različnimi koncentracijami feritnih delcev - primerjava eksperimentalnih vrednosti s teoretičnimi modeli Flow properties of polypropylene composites with different concentrations of ferrite particles - the comparison of experimental values with theoretical models Polimerni kompoziti z magnetnimi delci so mešanice, sestavljene iz termoplastov z dodanimi aditivi in različnimi prahovi z magnetnimi lastnostmi. Uporabljajo se za izdelavo vezanih magnetov, pri čemer polimer deluje kot vezivo, ki povezuje magnetne delce v želeno obliko. Zaradi zagotavljanja čim boljših magnetnih lastnosti, se pri tovrstnih materialih teži k čim večjemu deležu magnetnega prahu. Z večanjem deleža polnitve viskoznost narašča, kvalitetno brizganje taline postaja vedno težje, ohlajeni končni izdelki postajajo vse bolj krhki. V tem delu smo analizirali viskoznost visokopolnjenega polipropilena z različnimi deleži prahu stroncijevega ferita. Iz literature smo izbrali različne modele za napovedovanje strižno odvisne viskoznosti v odvisnosti od deleža trdnih delcev. Primerjali smo eksperimentalno dobljene vrednosti z izračuni ter izbrali model, ki najbolje opisuje obravnavane materiale. Ugotovili smo, da viskoznost narašča s povečevanjem deleža ferita. Meja prvega newtonskega območja viskoznosti se pri tem pomika k nižjim strižnim hitrostim. Odstopanja modelov od meritev so zelo odvisna od strižne hitrosti, pri kateri so bile meritve izvedene. Pri strižni hitrosti 1,06 1/s viskoznost najbolje napove Krieger-Doughtery-jev model in pri 10,6 1/s Chong-ov model. Polymer composites with magnetic particles are mixtures composed of thermoplastics with added additives and various powders with magnetic properties. They are used to make bonded magnets, with the polymer acting as a binder that binds the magnetic particles together in the desired shape. In order to ensure the best possible magnetic properties, the aim is to maximize the proportion of magnetic powder in such materials. As the content of filler increases, the viscosity increases, quality melt injection molding becomes more and more challenging and cooled finished products become increasingly brittle. In this work, we analyzed the viscosity of highly filled polypropylene with different proportions of strontium ferrite powder. From the literature, we selected different models for predicting shear-dependent viscosity, depending on the proportion of solid particles. We also compared the experimentally obtained values with calculations and chose the model that best describes the discussed materials. We found that the viscosity increases with increasing ferrite content. The limit of the first Newtonian viscosity range moves to lower shear rates. The deviations of the models from the measurements are highly dependent on the shear rate at which the measurements were made. At shear rate 1,06 1/s, the viscosity is best predicted by the Krieger Doughtery model and at 10,6 1/s by the Chong model. tokovne lastnosti strižno upadanje viskoznosti stroncijev ferit polipropilen tokovni modeli flow properties shear thinning strontium ferrite polypropylene flow models true false false [F. Štrubelj] Slovenski jezik Angleški jezik Zaključna naloga 2020-09-08 08:32:47 2020-09-08 08:32:50 2023-11-16 08:20:52 0000-00-00 00:00:00 2020 0 Ljubljana 0 XII, 26 f. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 532.13:678.742.3:549.73(043.2) 223725 28838915 6016.pdf 6016.pdf 1 377282D504E54A49D9CF6978489AC43E c5f73598005e636c4d509236f57405015a4c9433a97a7a304849ac9b95c0d232 cde470c8-a1b9-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=134056 Fakulteta za strojništvo 0 0 0