Thesis (MScFor)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The retention of filler particles and drainage are important aspects of papermaking. A
number of important paper properties depend in the quality and quantity of filler retained
in the paper. Fines, fillers and pulp fibres all have a negative charge and are kept apart by
electrostatic forces. This causes a decrease in the effectiveness of cationic retention aids
thereby causing a high cationic demand. This in turn implies that the retention of fines
and filler particles in a formed sheet is not efficient, especially in the presence of anionic
trash. In order to improve printability, print quality and dimensional stability, a large
percentage of mineral pigments / fillers either in the form of internal loading or external
coating should be added.
It was found that coflocculation of fines and filler particles resulted in an even
distribution of filler particles in the form of miero-flocs and the filler retention was
maintained. Opacity was improved without much reduction in paper strength. An
increased filler content without coflocculation of fines reduced sheet strength properties.
The filler particles interfered with the development of fibre-to-fibre bonds and occupied
spaces that otherwise might have contained fibres.
This study showed that the most beneficial effect of coflocculation of filler with fines was
obtained, with regards to paper strength, opacity, filler retention and printability, when
the charge of the fibre furnish was maintained at -0.1 leu with the 0.1% addition of
cationic PAM retention aid. / AFRIKAANSE OPSOMMING: Twee belangrike aspekte van papiervervaardiging is die retensie van vulstowwe en
ontwatering. 'n Aantal belangrike papiereienskappe is afhanklik van die hoeveelheid en
kwaliteit van vulstowwe wat in papier voorkom. Veselpuin, vulstowwe en pulp-vesels is
almal negatief gelaai, gevolglik verseker elektrostatiese kragte dat hierdie deeltjies los
van mekaar bly. Laasgenoemde verminder die doeltreffendheid van kationiese
retensiemiddels en dit gee aanleiding tot 'n hoë kationiese aanvraag. Die retensie van
veselpuin en vulstof deeletjies in papier is gewoonlik nie voldoende in die
teenwoordigheid van anioniese afvalkomponente nie. Om aan papier verbeterde drukeienskappe,
drukkwaliteit en dimensionele stabiliteit te gee, moet 'n groot persentasie
minerale pigmente en/of vulstowwe as 'n interne lading of eksterne bestryking voorsien
word.
Daar is bevind dat kot1okkulasie van fynstowwe en vulstofdeeltjies, 'n egalige
verspreiding van vulstof-partikels as mikro-t1okke tot gevolg het en dat vulstof-retensie
op aanvaarbare vlakke behou is. Ook is ondeurskynendheid verbeter sonder 'n
beduidende verswakking in die papiersterkte. 'n Toename in vulstofinhoud, sonder
kot1okkulasie van fynstowwe, het die papier sterkte-eienskappe verlaag. Vulstofdeeltjies
bëinvloed die ontwikkeling van vesel-tot-vesel binding. Hierdie deeltjies beset ruimtes
wat andersins deur vesels benut sou word.
Hierdie studie het getoon dat die voordeligste effek van kot1okkulasie van vulstowwe met
fynstowwe verkry is, ten opsigte van papiersterkte, ondeurskynendheid, vulstof retensie
en drukeienskappe, wanneer die lading van die pulpsuspensie by -0.1 leu gehou was met
'n byvoeging van 0.1% kationiese PAM retensie-hulpmiddel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/37370 |
| Date | 04 1900 |
| Creators | Matyumza, Ntombozuko C. |
| Contributors | Gerischer, G. F. R., Rypstra, T., Botha, A., Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 75 pages : illustrations |
| Rights | Stellenbosch University |
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