119 leaves single sided printed, preliminary pages and numbered pages 1-101. Includes bibliography and a list of tables, figures, schemes and abbreviations. Digitized at 300 dpi (OCR), used Bizhub 250. / Thesis (MSc (Polymer Science))--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The properties and interactions of cellulose surfaces are of a great technical interest
during papermaking and recycling. Sizing, the modification of fiber surfaces, e.g. with
the purpose to reduce water penetration into the paper structure, plays an important role
in obtaining paper with good printability and water resistance. Water resistance is the key
end-property of paper being investigated in this study.
Firstly a comparison was made between the degree of surface modification of cellulose
by means of anionic, nonionic and reactive surfactants. The amount of surfactant
adsorbed by the paperboard was determined and the paper surface evaluated via scanning
electron microscopy (SEM). The sizing efficiency of the three industrial surfactants was
evaluated in order to establish the surfactant structure best suited for sizing recycled
paperboard. This was done via the Cobb test, an industrial method to measure water
uptake by paper, and contact angle measurements. The reactive surfactant was found to
have the best sizing efficiency and focus shifted to synthesizing selected copolymer
surfactants via free radical copolymerization.
Two copolymers were synthesized, with maleic anhydride as the polar part in both. Butyl
methacrylate and lauryl methacrylate were selected as the hydrophobic parts in the
respective copolymer systems. The unavailability of reactivity ratios for the respective
copolymer systems led to the use of in situ proton nuclear magnetic resonance
spectroscopy CH NMR) for the determination of the co-monomer incorporation in both
copolymer systems. Quantitative 13C NMR spectroscopy was also employed in order to
establish the co-monomer content of the isolated copolymers obtained during bench-scale
(laboratory) experiments.
Lastly, a comparison of the degree of surface modification of cellulose was made
between that which was achieved with the industrial reactive surfactant and that with the
two synthesized polymeric reactive surfactants. The two synthesized polymeric
surfactants were found to have a better sizing efficiency than the industrial reactive
surfactant, and the maleic anhydride-lauryl methacrylate copolymer system gave the best
results. / AFRIKAANSE OPSOMMING: Die eienskappe en interaksies van sellulose-oppervlaktes is van groot tegniese belang
gedurende die vervaardiging en hergebruik van papier. Oppervlakte behandeling, die
modifikasie van vesel-oppervlaktes bv. met die doel om water indringing in die
papierstruktuur te verminder, speel 'n belangrike rol in die daarstel van papier met goeie
drukkwaliteit en waterweerstand. Waterweerstand is die sleuteleienskap van papier wat in
hierdie werkstuk ondersoek word.
Eerstens is daar 'n vergelyking getref tussen die verandering van sellulose-oppervlaktes
deur middel van anioniese, nie-ioniese en reaktiewe sepe. Die hoeveelheid seep
geabsorbeer deur die papierbord is bepaal en die papier-oppervlak ondersoek deur middel
van skandeer-elektronmikroskopie (SEM). Die behandelingsdoeltreffendheid van die drie
industriele sepe is ondersoek om vas te stel watter seep die beste struktuur het om
hergebruikte papierbord effektief te behandel. Dit is gedoen deur middel van die Cobbtoets,
'n industriele metode om wateropname van papier te meet, asook
kontakhoekmetings. Daar is gevind dat die reaktiewe seep die beste
behandelingsdoeltreffendheid het en daar is vervolgens gekonsentreer op die bereiding
van geselekteerde reaktiewe kopolimeersepe deur middel van vryeradikaalkopolimerisasie.
Twee kopolimere is berei, met maleienanhidried as die polere gedeeite van albei.
Butielmetakrilaat en laurielmetakrilaat is gekies vir die nie-polere gedeeltes van die
onderskeie kopolimeersisteme. Die onbeskikbaarheid van reaktiwiteitsverhoudings vir
die onderskeie kopolimeersisteme het gelei tot die gebruik van in situ proton kern
magnetiese resonansie spektroskopie eH KMR) vir die bepaling van die ko-monomeer
insluiting in beide kopolimeersisteme. Kwantitatiewe koolstofdertienkemmagnetieseresonansie
spektroskopie (13C KMR) is ook gebruik om die ko-monomeerinhoud van die
geisoleerde kopolimere, verkry tydens laboratoriumeksperimente, te bepaal.
Laastens is 'n vergelyking getref tussen die graad van modifikasie van selluloseoppervlaktes
deur middel van die industriele reaktiewe seep in vergelyking met die twee
bereide polimeriese reaktiewe sepe. Daar is gevind dat die twee gesintetiseerde
polimeriese sepe beter behandelingsdoeltreffendheid as die industriele reaktiewe seep het,
met die maleienanhidried-laurielmetakrilaat-kopolimeersisteem wat die beste resultaat
lewer.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4874 |
| Date | 03 1900 |
| Creators | Moses, Alvira |
| Contributors | Sanderson, R. D., Cloete, V., University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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