Production and use of agrofibre in Finland : final report study, IV part : reed canary grass sulphate pulp as raw material for fine paper

Suomen oloissa lyhytkuituista ruokohelpeä on mahdollista käyttää hienopaperin raaka-aineena. Ruokohelven kuitupituus ja pituusmassa ovat hieman alhaisemmat kuin koivumassalla, mistä on seurauksena suuri kuitumäärä massayksikössä. Non-wood-kuitujen tapaan ruokohelvelle on tyypillistä suuri hienoainemäärä, joka huonontaa massan suotautuvuutta. Koivuun verrattuna ruokohelpi sisältää vähemmän ligniiniä ja selluloosaa, mutta huomattavasti enemmän tuhkaa ja silikaattia. Ruokohelpi keittyy helposti kappalukuun 10 ja saanto on hyvä. Ruokohelpimassaa ei tarvitse happidelignifioida. Valkaisemattoman ruokohelpimassan ja happidelignifioidun koivumassan vaalenevuudessa ei ollut eroja. Fraktioitu, kyyppipesty ja happidelignifioitu ruokohelpi vaaleni myös TCF-sekvenssillä täysvaaleuteen kemikaalikulutusten ollessa varsin kohtuullisia. Ruokohelven korkea silikaattipitoisuus (1-5 %) aiheuttaa ongelmia talteenottolinjalla, jos sitä ei huomioida prosessia suunniteltaessa. Lehtimateriaalin ja pölyn poisto fraktioinnilla ennen keittoa pienentää silikaattipitoisuutta noin 40 %. Mustalipeästä silikaatti voidaan poistaa käyttämällä kaupallisia menetelmiä: saostamalla savukaasuilla tai kaksivaiheisella kaustisoinnilla. Lyhytkuituinen ruokohelpimassa antaa hienopaperille hyvät painettavuusominaisuudet, kun taas ajettavuuden edellyttämä lujuus saadaan pitkäkuituisella havumassalla. Ruokohelpikuidulla on hyvä sitoutumiskyky, joten sitä ei tarvitse jauhaa. Ruokohelpimassan repäisylujuus on pienempi, mutta murtotyö suurempi kuin jauhetulla koivumassalla. Myös ilmanläpäisyvastus on jonkin verran suurempi. Erot ovat kuitenkin koivumassan ominaisuusvaihteluiden rajoissa. Ruokohelven suuri kuitumäärä massayksikössä takaa massalle hyvät valonsirontaominaisuudet. Ruokohelven kasvupaikan maalaji ja korjuuajankohta aiheuttavat suuria vaihteluita raaka-aineen ominaisuuksiin. Kun ruokohelpi tuottaa runsaasti kortta, kasvaa multamaalla ja korjataan keväällä, siitä keitetyn massan saanto ja paperitekninen potentiaali hienopaperissa ovat samaa luokkaa koivumassan kanssa. Vaikka puhtaan ruokohelpimassan vedenpoisto-ominaisuudet ovat huonommat kuin koivumassan, laboratoriosimulointikokeet osoittivat, ettei näiden massojen välillä ole eroja rainan kosteuspitoisuudessa ennen puristinosaa eikä sen jälkeen. Kuivatussimulointikokeiden perusteella voi ruokohelpeä sisältävän paperin loppukosteus jäädä korkeammaksi kuin puumassasta valmistetun paperin ainoastaan silloin, kun kuivatusosa muodostaa "pullonkaulan" paperikoneessa. Pilotpaperikoneella tehdyissä kokeissa ei höyrynkulutuksessa eikä kuivaussylintereiden lämpötiloissa havaittu eroja lisättäessä ruokohelpimassan osuutta pohjapaperissa. Entsyymikäsittelyllä voidaan tarvittaessa parantaa ruokohelpimassan vedenpoistokykyä. Laboratoriomitassa saadut tulokset ruokohelpimassan soveltuvuudesta hienopaperin raaka-aineeksi varmistettiin pilotmittakaavaisissa koeajoissa, joissa valmistettiin päällystettyä ja pintaliimattua hienopaperia. Paperia koepainettiin arkkioffsetpainokoneella. Pilotkoeajojen perusteella ruokohelpimassalla voidaan joko osittain tai kokonaan korvata koivusellu päällystetyssä ja pintaliimatussa hienopaperissa ajettavuuden tai laadun kärsimättä.Reed canary grass is a potential producer of short fibre for fine paper in Finland. Its fibre length and coarseness are somewhat lower than those of birch, yielding a large amount of particles per unit weight of pulp. Like other non-wood fibres, reed canary grass has a high fines content, which impairs the dewatering properties of pulp. Reed canary grass pulp contains less lignin and cellulose but much more ash and silica than birch pulp. Reed canary grass cooks easily to kappa level 10 and the yield is good. No oxygen delignification is needed. There were no differences in bleachability between unbleached reed canary grass pulp and oxygen-delignified birch pulp. When fractionated and pre-washed reed canary grass was used, full brightness was also reached with oxygen-delignified TCF pulp, chemical consumption still being very reasonable. The high silicon content of reed canary grass, 1-5%, causes problems in the recovery system if not taken into account in the process design. The removal of leaves and dust with air fractionation before cooking decreases the silicon content by about 40%. Silicon can be removed from black liquor with commercial desilication techniques, by precipitation with flue gases or by two-stage causticization. Short-fibred reed canary grass pulp gives fine paper good printing properties, while the strength required for runnability is adjusted by adding long-fibred softwood pulp. Reed canary grass fibres have a good bonding ability and need not be refined. The tear strength of the pulp is lower than that of refined birch pulp, but the TEA is higher; Air resistance is also somewhat higher. The differences are, however, within the limits of the property variations of mill birch pulp. The large amount of particles per unit weight of reed canary grass guarantees that the paper has good light scattering properties. Reed canary grass raw material properties are highly dependent on both the soil type at the growing place and the development stage of the plant at harvest. If reed canary grass is grown in humus-rich soil, produces a large stem fraction and is harvested by the delayed harvesting system, its pulp yield and papermaking potential are comparable to those of birch pulp. Although the dewatering ability of pure reed canary grass pulp is inferior to that of birch pulp, laboratory simulation tests showed that there are no differences in sheet dryness before or after pressing irrespective of whether birch or reed canary grass is used as the short-fibre pulp. Drying results indicate that only if the paper machine is drying-limited is there a possibility that the end moisture content of paper will be higher if reed canary grass is used in the furnish instead of woodpulp. When the proportion of reed canary grass pulp in the base paper was increased in pilot paper machine trials, no differences could be detected in steam consumption or in drying cylinder temperatures. Dewatering of reed canary grass pulp can be improved with enzymatic treatment if necessary. The results of the laboratory tests were confirmed in pilot-scale trials by making coated and surface-sized fine paper and by testing the printability of the paper in offset printing. The trials indicated that birch pulp can be replaced in part or entirely by reed canary grass pulp in coated or surface-sized fine paper without adversely affecting the runnability or the quality of the paper.vokMyynti MTT tietopalveluyksikk

Correlation between Knowledge, Experience and Common Sense, with Critical Thinking Capability of Medical Faculty’s Students at Indonesia Christian University

This research discusses correlation between knowledge, experience and common sense with critical thinking of Medical Faculty’s Student. As to the objective of this research is to find the correlation between knowledge, experience and common sense with critical thinking of Medical Faculty’s Students at Christian University of Indonesia. It is conducted in Christian University of Indonesia at Medical Faculty precisely, which of 72 students had been elected as research from total population of 250 students who actively attend Medical Educational Program of 2011/2012. Random sampling technique is the the applied one, it is questionnaire comprising 34 questions. The Data analyzed by Skewness and Kurtosis test. Research finding had obtained that knowledge, experience and common sense has positive correlation with critical thinking of students. As to correlational coefficient between variable X1, X2 and X3 to Y is 0.234. Hence, it may be concluded that to increase critical thinking capability of students then, knowledge, experience and common sense should be increased as well

Quality and yield of pulpwood in drained peatland forests : Pulpwood properties of Scots pine in stands of first commercial thinnings

The inherent structural dynamics of drained peatland forests may result in a great variation in various wood and fi ber properties. We examined variation in fi ber and pulp properties i) among stands, ii) among trees within stands, and iii) within trees in young stands dominated by Scots pine (Pinus sylvestris L.). The stands, selected to cover a maximal range of the potential variation, were all at a stage of development where the fi rst commercial thinnings would be feasible. Differences in the processability of the thinning removals were small. In similar kraft cooking conditions, a 5-unit variation in the kappa number of unbleached pulp was observed among the stands. Stand origin had no effect on pulp bleaching. The wood formed prior to drainage had a higher density, shorter fi bers, was slightly slower delignifi ed by cooking, and its yield was slightly lower than that of post-drainage wood. These properties, except for high density, are typical for juvenile wood in general, and at stand level they did not correlate with the proportion of pre-drainage wood. When the variation in fi ber and pulp properties was broken down into its components, most of it was derived from tree-level in all the cases. On average, the fi ber and pulp properties did not differ from those observed for fi rst-thinning pulpwood from upland sites. Consequently, peatland-grown pulpwood may be mixed with other pulpwood in industrial processes. It would probably be best suited as the raw material for pulps with high bonding requirements, e.g. in the top ply of multi-ply board grades or in some specialty grades

Effect of genotype and growing conditions on fibre and mineral composition of reed canary grass (Phalaris arundinacea L.)

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