Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study involved the analysis of crystallization kinetics by means of a unique and newly
developed Solution crystallization analysis by laser light scattering (Scalls) technique. In the main
study we compared two commercial linear low-density polyethylene (LLDPE) polymers (PE-1-
octene and PE-1-hexene) and studied the effect of short-chain branching on the solution
crystallization of these complex polymer systems. Characterization of the polymers was done by
nuclear magnetic resonance spectroscopy (NMR) and high-temperature gel permeation
chromatography (HT-GPC).
The second study involved the fractionation of a PE-1-hexene copolymer by temperature rising
elution fractionation (Tref) and analyzing the solution crystallization of the different temperature
fractions. This resulted in important details on the different molecular regions present in the
polymer.
A third additional study was done on the compatibility in polyolefin blends. Two different blends
were prepared: isotactic polypropylene (iPP) – low density polyethylene (LDPE) blend and iPP –
polypropylene impact copolymer (PPIC) blend. It was found that co-crystallization only occurred
for the iPP - PPIC blends. Phase separation occurred for the iPP – LDPE blends, resulting in the
formation of two phases for all blend compositions.
Solution crystallization analysis is usually measured by the conventional Crystallization Analysis
Fractionation (Crystaf) technique. In this study all crystallization data were compared with Crystaf
results and a good correlation was found between the results obtained by Crystaf and Scalls. The
major advantages of the Scalls technique are that, results similar to that of Crystaf can be acquired
with much shorter analysis times and Scalls also allows for the measurement of solution melting of
the crystallized polymer solutions. / AFRIKAANSE OPSOMMING: Hierdie studie het die analise van kristallisasie kinetika behels met behulp van die unieke en nuut
ontwikkelde oplossing kristallisasie analise deur laser lig verstrooiing (Scalls) tegniek. In die hoof
studie het ons twee kommersïele liniêre lae-digtheid polietileen (LLDPE) polimere (PE-1-okteen en
PE-1-hekseen) vergelyk en die effek van kort-ketting vertakking op kristallisasie in oplossing van
hierdie komplekse polimeer sisteme bestudeer. Karakterisering van die polimere was gedoen met
kern magnetiese resonans spektroskopie (KMR) en hoë-temperatuur gel permeasie kromatografie
(HT-GPC).
Die tweede studie het die fraksionering van ‘n PE-1-hekseen ko-polieer met behulp van
temperatuurstyging eluering fraksionering (Tref) behels asook die analisering van kristallisasie in
oplossing van die verskillende temperatuur fraksies. Belangrike informasie oor die verskillende
molekulêre areas teenwoordig in die polimeer was verkry.
‘n Derde addisionele studie was gedoen op die versoenbaarheid in poliolefin mengsels. Twee
verskillende mengsels was voorberei: isotaktiese polipropileen (iPP) – lae digtheid polietileen
(LDPE) mengsel en iPP – polipropileen impak ko-polimeer (PPIC) mengsel. Daar was gevind dat
ko-kristallisasie slegs in die iPP – PPIC mengsel plaasgevind het. Fase skeiding het plaasgevind in
die iPP – LDPE mengsels wat tot twee fases gelei het vir alle mengsel komposisies.
Kristallisasie in oplossing word gewoonlik gemeet met die konvensionele kristallisasie analise
fraksionering (Crystaf) tegniek. In hierdie studie was al die kristallisasie data met Crystaf resultate
vergelyk en ‘n goeie korrelasie was gevind tussen die resultate van Crystaf en Scalls. Die grootste
voordele van die Scalls tegniek is dat resultate soortgelyk aan diè van Crystaf kan verkry word met
baie korter analises en Scalls laat ook toe vir die meting van smeltpunt van die gekristalliseerde
polimeer oplossings.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/20112 |
| Date | 03 1900 |
| Creators | Robertson, Divann |
| Contributors | Van Reenen, Albert J., Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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