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Titolo:
Positron annihilation lifetime spectroscopical study of kraft pulps after individual bleaching stages and beating
Autore:
Pekarovicova, A; Venditti, RA; Cao, H; Lou, YM; Jean, YC;
Indirizzi:
Western Michigan Univ, Dept Paper & Printing Sci & Engn, Kalamazoo, MI 49008 USA Western Michigan Univ Kalamazoo MI USA 49008 ngn, Kalamazoo, MI 49008 USA N Carolina State Univ, Coll Forest Resources, Dept Wood & Paper Sci, Raleigh, NC 27695 USA N Carolina State Univ Raleigh NC USA 27695 per Sci, Raleigh, NC 27695 USA Univ Missouri, Coll Arts & Sci, Dept Chem, Kansas City, MO 64100 USA Univ Missouri Kansas City MO USA 64100 pt Chem, Kansas City, MO 64100 USA
Titolo Testata:
CELLULOSE CHEMISTRY AND TECHNOLOGY
fascicolo: 5-6, volume: 33, anno: 1999,
pagine: 483 - 493
SICI:
0576-9787(199909/12)33:5-6<483:PALSSO>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
FREE-VOLUME HOLE; POLYMERS;
Keywords:
positron annihilation lifetime spectroscopy (PAL); fractional free volume; micropores; bleaching; Kappa number; beating; freeness; Kajaani fiber analysis; WRV;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
Citazioni:
18
Recensione:
Indirizzi per estratti:
Indirizzo: Pekarovicova, A Western Michigan Univ, Dept Paper & Printing Sci & Engn, Kalamazoo, MI 49008 USA Western Michigan Univ Kalamazoo MI USA 49008 MI 49008 USA
Citazione:
A. Pekarovicova et al., "Positron annihilation lifetime spectroscopical study of kraft pulps after individual bleaching stages and beating", CELL CHEM T, 33(5-6), 1999, pp. 483-493

Abstract

After delignification and individual bleaching stages, commercial hardwoodand softwood kraft pulps were beaten to several freeness levels and standard handsheets were formed. The microporous structure of handsheets was studied by means of positron annihilation lifetime spectroscopy (PAL). Kajaani fiber analysis showed slight shortening of bleached softwood fibers, while beaten to about 100 mt CSF. The fines' content increased due to beating, mainly in bleached softwood pulp. WRV values of never dried pulps increased by about 35% in softwood and by 30% in hardwood after beating. I-3, the intensity of o-Ps annihilation, which is related to fractional free volume, wasround to increase due to both delignification and beating. The bleaching process affects only slightly the microporous structure of these pulps, the average pore size decreasing for both hardwood and softwood. Fractional free volume or fractional volume of pore holes increased due to the bleaching process for both types of pulp. From the decrease of average micropore sizeand the increase of the fractional free volume, the creation of completelynew free volume pore holes during the bleaching process can be observed. The fractional free volume of all pulps slightly increased during the beating process, which is more obvious with bleached than with unbleached or partially bleached ones.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/03/20 alle ore 04:45:20