Utjecaj lužine na površinska svojstva aluminijevog oksida

Gojo, Katarina (2010) Utjecaj lužine na površinska svojstva aluminijevog oksida. Diploma work - Pre-Bologna programme. Grafički fakultet. [Mentor: Mahović Poljaček, Sanja].

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Abstract

Zavisno o koncentraciji razvijača određivani su parametri površinske hrapavosti, kontaktni kut, te slobodna površinska energija (SPE) na Al2O3 kao materijalu slobodnih površina tiskovnih formi za ofsetni tisak. Kao razvijač upotrijebljena je vodena otopina NaOH različitih koncentracija, a kao standardi za mjerenje kontaktnog kuta i SPE korišteni su dijodmetan, glicerol i voda. Djelovanjem NaOH na površinu Al2O3 dolazi do njegovog otapanja, te tako, na određeni način i do poliranja površine što pokazuju izmjereni parametri hrapavosti. Smanjenje Rp i Rv vrijednosti ukazuje na promjenu hrapavosti površine. Prevlaka anodnog sloja je manje hrapava, a time se smanjuje broj aktivnih točaka za adsorpciju molekula otopine za vlaženje. Zavisno o upotrijebljenom standardu kontaktni kut na slobodnim površinama se u početku smanjuje povećanjem vremena razvijanja, da bi kasnije dolazilo do njegovog povećanja. Produljenje vremena kemijskog djelovanja otopine NaOH svih ispitivanih koncentracija najprije uzrokuje neznatno povećanje slobodne površinske energije, a kasnije njeno smanjenje. Udio disperzne faze slobodne površinske energije kod svih uzoraka gotovo je nepromijenjen neovisno o vremenskom intervalu izlaganja djelovanju otopini razvijača, dok polarna faza pokazuje slično ponašanje, odnosno, raste do postizanja maksimalne vrijednosti, nakon čega se smanjuje.

Item Type:	Diploma work - Pre-Bologna programme
Mentor name:	Mahović Poljaček, Sanja
Defence date:	30 September 2010
Abstract in english:	Parameters of surface roughness, contact angle and surface free energy (SFE) on Al2O3 as a material wich is used as the non-image areas for the offset tehnique has been determined depending on the concetration of the developing solution. Different concentration of NaOH water solution has been used as the developing solution, and diiodomethane, glycerol and water were used as standars for measuring the contact angle and surface free energy. NaOH solution has caused the dissolution of Al2O3 surfaces during the developing process. By dissolution of Al2O3 peaks of the nonprinting elements the platous has been formed and could be dectected by measuring the surface roughness parameters. Decreasing of Rp and Rv values have indicated the changes in surface roughness. The anode layer had lower vaues of roughness which caused the reducing of the number of acticve points for the adsorption of fountain solution. Depending on the used standard, contact angle values on the non-image areas initially have been decreased with increasing of development time, but with certain increase in later stages. Longer development in all concentrations of NaOH has caused a slight increasing of SFE in the first stages with certain decrease in the later stages. The disperse components of SFE on all observed samples of plates has been unchanged regardless of the developing duration. Similar results have been detected with the polar components where the values have been increased in the first stage followed by decreasing in the other stages.
Uncontrolled Keywords:	kontaktni kut, površinska hrapavost, slobodna površinska energija, tiskovna forma
Keywords in english:	contact angle, surface free energy, printing plate, surface roughness
Subjects:	TECHNICAL SCIENCES > Graphic Technology
Institution:	Grafički fakultet
City:	Zagreb
Number of Pages:	46
Callnumber:	mah 2009 goj
Inventory number:	D855
Status:	Unpublished
Date Deposited:	15 Nov 2013 21:38
Last Modified:	06 May 2014 11:48
URI:	http://eprints.grf.unizg.hr/id/eprint/832

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