The use of fluorescence to probe the morphology changes in complex polymers

Le Grange, Marehette Suzanne (2015-04)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Impact polypropylene copolymers (IPC) are commercially used in a variety of applications. They are very complex materials and extensive studies have been conducted to understand the relationship between their chemical structure, morphology and impact properties. The distribution of ethylene propylene rubber (EPR) within IPC has drawn much attention but visualization of the morphology is difficult. In this study a fluorescent marker was used to probe the distribution of EPR within the crystalline and semi-crystalline fraction. The EPR was removed from a commercial IPC and labelled with a fluorescent marker. In this study a method utilizing the hydrophilic nature of cellulose nanowhiskers (CNW) was developed to label the EPR. CNW were labelled with fluorescein-5’-isothiocyanate (FITC) and rhodamine B (RhB) using a one-step procedure. The labelled CNW were incorporated into the EPR by means of sonication. The mobility of the labelled CNW within the EPR film was investigated by confocal fluorescence microscopy (CFM), and showed that the labelled whiskers did not move within the EPR, thus substantiating the validity of this approach. The labelled EPR was recombined with the crystalline fraction by means of injection moulding and was analysed by CFM, and the distribution of the labelled EPR was evaluated. Confocal fluorescence microscopy showed an even distribution of the labelled rubber throughout the injection moulded sample. The miscibility of two EPRs within the IPC matrix in the melt was also investigated using this technique. CFM showed that the technique has promise to prove miscibility or the lack thereof when chemically similar materials are combined in the presence of morphologically different matrix materials.

AFRIKAANSE OPSOMMING: Impak polipropileen kopolimere (IPK) word kommersieel gebruik in ‘n wye reeks produkte. Die samestelling van hierdie kopolimere is baie ingewikkeld en uitgebreide studies is al gedoen om hul chemiese samestelling op molekulêre vlak te verstaan. Baie studies met betrekking tot die verspreiding van die etileen-propileen rubber (EPR) binne in hierdie impak polipropileen kopolimere is al gedoen, maar visualisering van die morfologie is moeilik en beperk. Hierdie kennis kan bydra tot die verbetering van hul chemiese eienskappe en toepassings. In hierdie studie word ʼn fluorosserende merker gebruik om die verspreiding van die EPR binne die kristallyne en semikristallyne fraksie te ondersoek. Die EPR is verwyder vanuit 'n kommersiële IPK en is gemerk met 'n fluoresserende merker. In hierdie studie is 'n metode ontwikkel om die EPR te merk deur gebruik te maak van die hidrofiliese eienskap van sellulose nanovesels (SNV). Die SNV is gemerk met fluoressien-5'-isotiosianaat (FITC) en rhodamien B (RhB) met behulp van 'n eenstap proses. Die gemerkte SNV is deur middel van sonikasie in die EPR versprei. Die mobiliteit van die gemerkte SNV binne-in die EPR film is ondersoek deur gefokusde fluoressensie mikroskopie (GFM) en het getoon dat die gemerkte vesels nie binne die EPR beweeg nie. Dit bevestig dus die geldigheid van hierdie benadering. Die gemerkte EPR is herkombineer met die kristallyne fraksie deur middel van spuitgiet en is geanaliseer deur GFM en die verspreiding van die gemerkte EPR is geëvalueer. GFM het 'n eweredige verspreiding van die gemerkte rubber regdeur die moster wat gespuitgiet is getoon. Die mengbaarheid van twee EPRs binne-in die IPK matriks is ook ondersoek deur gebruik te maak van hierdie tegniek. GFM het getoon dat hierdie tegniek waarde inhou om te bewys dat twee produkte mengbaar is of nie, al word hulle geherkombineer word met ‘n matriks wat morfologiese van hul verskil.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96820
This item appears in the following collections: