20.500.12556/RUL-122421 Vpliv sestave urea-formaldehidnega lepila na njegove reološke in dielektrične lastnosti med procesom utrjevanja magistrska naloga Effect of composition of urea-formaldehyde adhesive on its rheological and dielectric properties during curig process M. Sc. thesis Proučevali smo vpliv sestave urea-formaldehidne lepilne mešanice na reološke in dielektrične lastnosti med utrjevanjem. Vzorci lepila so se med seboj razlikovali v molarnem razmerju med ureo in formaldehidom; eden od vzorcev pa je vseboval dodatek melamina. Lepilne mešanice so bile že predhodno pripravljene, pred poskusom jim je bilo treba dodati le še katalizator. Testiranja smo izvajali z reometrom ARES-G2, ki je bil povezan z računalnikom in LCR-metrom. Tako nam je bilo omogočeno, da smo hkrati spremljali reološke in dielektrične lastnosti lepila med procesom utrjevanja. Pripravljeno lepilno mešanico smo nanesli na aluminijaste diske, jih približali na želeno razdaljo in sprožili meritev. Temperatura segrevanja večine vzorcev je bila od 30 °C do 85 °C. Iz podatkov meritev smo za posamezne vzorce izračunali stopnjo utrjenosti. Ugotovili smo, da molarno razmerje med ureo in formaldehidom vpliva na reološke in dielektrične lastnosti, prav tako kot dodatek melamina ali moke. Pri večjih količinah dodanega katalizatorja smo beležili višje vrednosti obeh komponent strižnega modula in prevodnosti, same reakcije utrjevanja pa so potekale hitreje. Opazili smo korelacijo med rezultati obeh metod in sicer na osnovi tipičnih točk konverzije lepila, kot sta točka želiranja in zamreženja. Ugotovili smo tudi precejšno podobnost med izračuni stopnje utrjenosti iz elastičnega strižnega modula in prevodnosti, zlasti pri večjem dodatku katalizatorja. Effect of urea-formaldehyde adhesive composition on rheological and dielectric properties during curing was examined. The main difference among adhesive samples was different molar ratio between urea and formaldehyde. One sample also contained melamine. Adhesive mixtures were pre-prepared, we just added a catalyst before testing. Tests were made using rheometre ARES-G2, connected to a computer and LCR metre. In this way we gained ability to analyze rheological and dielectric properties together during curing. A sample of a prepared adhesive mixture was applied on aluminium discs. Then we approached discs on a required distance and launched measurement. The heating temperature was set from 30 °C to 85 °C for most of the samples. From the test data, the degree of curing was calculated for each sample. We found out that the molar ratio between urea and formaldehyde affected rheological and dielectric properties, just as an addition of melamine and flour. When the quantity of the catalyst was higher, higher values for both components of shear modulus and conductivity were recorded, and also the curing reaction was faster. On the basis of typical points of adhesive conversion, as gel and vitrification points, a correlation between the results of both methods was detected..Significant similarity among the results of degree of curing calculated out of storage modulus and conductivity was discovered as well. dielektrične lastnosti prevodnost reologija strižni modul urea-formaldehidno lepilo utrjevanje dielectric properties conductivity rheology shear modulus urea-formaldehyde adhesive curing true false false [B. Cilenšek] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2020-12-10 11:27:12 2020-12-10 11:27:22 2022-09-02 04:03:14 0000-00-00 00:00:00 2013 0 Ljubljana 2013 Ljubljana XII, 50 f. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*824.843 2169481 MAG_Cilensek_Boris_2013.pdf MAG_Cilensek_Boris_2013.pdf 1 7BEDB7D0E5CA41B00EB85E22104D0351 e0db52421a059accc75ee2aa21f0e173b4948787139b53a1c06bc7a3532beade 1a234658-a1bb-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=137606 Biotehniška fakulteta 0 0 0