Browsing by Author "Retulainen, Elias"
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Item CTMP-kuidun kemiallisen koostumuksen ja eräiden kuivakemikaalien vaikutus kuituverkoston lujuuteen(1991) Nurminen, Ilkka; Retulainen, Elias; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Sjöström, EeroItem Dewatering of foam-laid and water-laid structures and the formed web properties(SPRINGER, 2020-02-01) Lehmonen, Jani; Retulainen, Elias; Paltakari, Jouni; Kinnunen-Raudaskoski, Karita; Koponen, Antti; Department of Bioproducts and Biosystems; Paper Converting and Packaging; VTT Technical Research Centre of Finland; Paptic LtdThe use of aqueous foams as a carrier fluid for pulp fibers instead of water has re-emerged in the paper and board industry in recent years. In foam forming, a surfactant is needed to reduce the surface tension of the carrier liquid and to create foam as a process fluid and flowing medium. This presents the following questions: (1) How do the water forming and foam forming processes differ? (2) How do the obtained wet/dry fibre sheets differ after forming and after wet pressing? (3) Which differences in the process behavior and sheet properties are due to the surfactant, and which are due to the presence of air bubbles in the flowing medium? The answers to these questions were sought by using an experimental academic approach and by applying a special dynamic vacuum assisted sheet former. Although foams are much more viscous than water, dewatering times were found to be approximately equal in water and foam forming at higher vacuum levels. The hydrodynamic resistance of sheet was approximately constant during water forming, while in foam forming resistance was initially even smaller than in water forming but it increased with time, being substantially higher at the end of the forming process. In certain cases, surfactant alone was found to have a similar, albeit often lower, effect on the sheet properties of foam. Surfactant improved sheet dryness (both after forming and wet pressing), lowered density, and lowered strength properties also in water forming. Foam, on the other hand, had a crucial effect particularly on certain structural properties such as formation and porosity. The difference between water and foam-laid sheets typically reduced in line with higher wet pressing pressure. This suggests that the role of surface tension and foam bubbles in controlling interfiber contact is overridden by wet pressing pressure. Thus applying foam as a carrier fluid has characteristic effects both on the papermaking process and the end product properties. The main features of foam forming can be explained by the chemical effects caused by the surfactant, and the structural effects caused by the foam bubbles. Graphic abstractItem The effect of chemical additives on the strength, stiffness and elongation potential of paper(AB SVENSK PAPPERSTIDNING, 2017) Strand, Anders; Khakalo, Alexey; Kouko, Jarmo; Oksanen, Antti; Ketola, Annika; Salminen, Kristian; Rojas, Orlando; Retulainen, Elias; Sundberg, Anna; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Åbo Akademi University; VTT Technical Research Centre of FinlandThe effects of wet-end additions of cationic starches and/or carboxymethyl cellulose (CMC) on paper properties was determined by papermaking trials. The aim of this study was to mitigate the distinctive decrease in strength and stiffness due to unrestrained drying by addition of wet-end additives, while maintaining the extraordinarily high stretch potential of papers after unrestrained drying. Addition of the different polysaccharides increased the tensile index and density of the paper. The largest incgtreases in tensile index and stiffness were seen when combining cationic starches with CMC. With certain combinations of cationic starch and CMC, it was possible to increase the tensile index and stiffness of the paper, while maintaining the high elongation at break after unrestrained drying. To complement the results from the papermaking trials, adsorption of cationic starches and CMC onto cellulose nanofibril model surfaces was studied by QCM-D and SPR techniques. The additives adsorbed onto cellulose surfaces as soft gels, containing a large amount of coupled water. Adsorption of soft and malleable polysaccharide layers in the fiber-fiber joints enhanced the paper properties significantly on a macroscopic level. The softest and most swollen polysaccharide layers resulted in the largest increases in tensile index and stiffness of paperItem The effect of cylinder surface contamination to separation work(2008) Linja-aho, Aaro; Retulainen, Elias; Puunjalostustekniikan laitos; Teknillinen korkeakoulu; Helsinki University of Technology; Laine, JanneDiplomityön tavoitteena oli löytää irrotustyötä ja likaantumista vähentäviä tekijöitä paperikoneen ajettavuuden parantamiseksi. Kokeet tehtiin laboratoriomittakaavassa mallintaen alkukuivatusosan olosuhteita. Tutkimusta tehtiin VTT:n adheesiolaitteella ja TKK:n pinta-analyysimenetelmillä, kuten Raman-spektroskopialla, kontaktikulmamittauksilla ja ESCA:lla. Kirjallisuusosan perusteella adheesio ja likaantumisilmiöt ovat monimutkaisia kokonaisuuksia, joiden tutkiminen vaatii monien muuttujien vakioimista. Tärkeimpiä vaikuttavia tekijöitä ovat vuorovaikuttavat pinnat ominaisuuksineen ja nämä pinnat yhteen liimaava väliaine. Myös olosuhteet kuten lämpötila ja irrotusnopeus, vaikuttavat. Kirjallisuusosan perusteella hydrofobinen pintamateriaali on irrotusominaisuuksiltaan parempaa kuin hydrofiilinen, paras pintamateriaali on heterogeeninen pinta. Paperin lämpötila ja kuiva-ainepitoisuus vaikuttavat irrotustyöhön ja likaantumiseen merkittävästi. Matala tai korkea lämpötila vähentää irrotustyötä, kun taas kuiva-ainepitoisuuden tulee olla yli 50 % ongelmien vähentämiseksi. Pintoja likaavat ennen kaikkea hydrofobiset lika-aineet, jotka rikastuvat telapintoihin. Telapinnan ja paperin yhteen liittävän prosessiveden ominaisuudet muuttuvat vesifilmin paksuuden, lämpötilan ja sen sisältämien ainesosien suhteen. Irrotustyö on suurimmillaan, kun vesifilmi on ohut ja kun se sisältää paljon LK-aineita. Massoista mekaaninen massa johtaa suurempaan irrotustyöhön ja likaantumiseen kuivatusosalla, ja kemiallinen puolestaan suurempaan irrotustyöhön keskitelalla. Kokeellisen osan mittaustulosten perusteella mekaaninen massa tarttuu sileään telapintaan kemiallista massaa enemmän. Tutkituista telapinnoista pinta 2 on 45-80 °C:n lämpötiloissa irrotusominaisuuksiltaan parempi kuin pinta 1. 110 °C:ssa puolestaan pinta 1 antaa pienemmän irrotustyön. Likaantumiskäyttäytyminen on puolestaan pinnalla 1 parempi eli irrotustyö pienenee pinnan likaantuessa. Ilmiötä selittää ilmeisesti pinnan muuttuminen heterogeeniseksi likaantumisen myötä. Lämpötila ja kuiva-ainepitoisuus vaikuttavat irrotustyöhön kirjallisuuden mukaisesti. ASA:n hydrolyysituote muodostaa adheesiota voimakkaasti lisäävää kalsiumsaippuaa kalsiumin kanssa. Adheesiolaitteen, kontaktikulmamittausten ja Raman-spektroskopian avulla voidaan ymmärtää likaantumisilmiöitä sekä niiden vaikutusta irrotustyöhön ja siten adheesio-ilmiöön.Item Effect of the Condebelt method on printability(1999) Kangas, Jussi; Retulainen, Elias; Puunjalostustekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Oittinen, PirkkoItem Extensible Cellulosic Fibre-polyurethane Composites Prepared via the Papermaking Pathway(NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI, 2018) Vishtal, Alexey; Khakalo, Alexey; Retulainen, Elias; Department of Forest Products Technology; VTT Technical Research Centre of FinlandFormable papers can be used as an alternative to rigid plastics for making 3D shapes for packaging applications. However, commercial use of formable paper is currently limited, due to its poor extensibility. Cellulosic fibres can be combined with polyurethanes to improve the deformability of resulting fibre-polymer composites. This work describes the effect of spray and wet-end addition of polyurethane dispersions to paper to enhance the extensibility and formability of paper. The increase in extensibility was directly proportional to the amount of polyurethane retained in the paper. Absolute improvements in extensibility were as high as 4 to 6 percentage points. Improved extensibility resulted in better formability of paper, which eventually could allow it to compete with plastic packaging in certain applications.Item Foam forming under dynamic conditions(NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI, 2020-08) Lehmonen, Jani; Retulainen, Elias; Kraft, Marko; Paltakari, Jouni; Kinnunen-Raudaskoski, Karita; Department of Bioproducts and Biosystems; Paper Converting and Packaging; VTT Technical Research Centre of Finland; Paptic LtdUsing foam as a carrier fluid in papermaking gives interesting new opportunities. Foam as a more viscous fluid than water is expected to behave differently in a dynamic process. This study presents results obtained under dynamic forming conditions in a semi-pilot scale research environment. Effects of process configurations and running conditions on increased forming speed, web properties, and difference between waterlaid and foam-laid processes are shown. The studies were carried out using a water-laid former and the same environment modified for foam forming. In order to achieve increased forming speed, the open headbox was replaced with a closed headbox, and the former geometry was updated. The process foam was boosted with an additional foam pulper. The foam pulper was used as a machine chest for improving the dispersion of fibers into the foam. A much broader tensile strength ratio range (~3 to 8) was achieved with foam forming than with water-laid forming. Foam-laid paper had a broader pore size distribution and higher mean pore size. Formation and the formation spectra of foam-laid sheets were more uniform, leading to improvements in the properties of the fiber network.Item Formflow-nestepakkauskartongin syväpainettavuuden optimointi(1989) Heikkinen, Hannu; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Furfuraalijätteen soveltuvuus flutingin lisäraaka-aineeksi(1980) Retulainen, Elias; Ranua, Jukka; Puunjalostusosasto; Teknillinen korkeakoulu; Helsinki University of Technology; Ebeling, KariItem Hienoainelajin ja tärkkelyksen vaikutus kuituverkoston ominaisuuksiin(1995) Nieminen, Kaarina; Retulainen, Elias; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Paulapuro, HannuItem HSWO/LWC-painopaperin painopinnan kiillon ennustaminen(1989) Hohtari, Heikki; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Kirjekuoripaperin prosessoitavuus kirjekuorikoneella(1989) Björkenheim, Erik; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Kuivatusmenetelmän vaikutukset kartongin ja sen kuitujen pintaominaisuuksiin ja lisäaineiden toimintaan(1998) Pirhonen, Meri; Retulainen, Elias; Puunjalostustekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Stenius, PerItem Paperin sidoslujuuden mittausmenetelmien vertailu(1986) Retulainen, Elias; Puunjalostusosasto; Teknillinen korkeakoulu; Helsinki University of Technology; Ebeling, KariItem Pigmenttipäällystetyn nestepakkauskartongin offsetpainettavuuden parantaminen(1990) Pousi, Mika; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Polyeteenipäällystettyjen juomakuppikartonkien saumautuvuuden parantaminen(1990) Härmälä, Kalle; Nevalainen, Anne; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Tapettikartongin esiliisteröinti(1990) Saaristo, Martti; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, EliasItem Tyypillisten tarraliimojen soveltuvuus liuotinvapaalla silikonoinnilla valmistetulle irrokepaperille(1988) Turva, Merja; Prosessi- ja materiaalitekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Retulainen, Elias
