The effect of molecular architecture on the properties of propylene impact copolymers

Basson, N. C. (2010-03)

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.

Thesis

ENGLISH ABSTRACT: Impact polypropylene copolymers (IPPC) are important commercial materials, but their morphology and molecular architecture are not yet fully understood. In this study the focus was on selectively removing specific fractions from the original IPPC, recombining the remaining fractions, and studying the properties of these recombined polymers. It was found that some properties of the samples changed remarkably, depending on the fraction of material that was removed before recombination. For example, the degree of phase separation and the crystalline morphology of the recombined materials varied noticeably. During the study an effective way of staining samples for transmission electron microscopy (TEM) was developed. Furthermore, a comparison of fourier transform infrared spectroscopy (FTIR), with TEM and scanning electron microscopy (SEM) results, revealed a hitherto unreported relationship between phase separation. Absorption bands appeared at 1100 cm-1 and 1080 cm-1 in the FTIR spectra and appear to be an indication of phase separation. It was further established that specific copolymer fractions present in the original polymer affect not only the morphology of the final polymer, but also the hardness and impact resistance.

AFRIKAANSE OPSOMMING: Impak polipropileen kopolimere (IPPK) is belangrike kommersïele materiale, maar die kennis met betrekking tot die morfologie en molekulere argitektuur van die materiale is nog gebrekkig. Tydens hierdie studie was die fokus op die selektiewe verwydering van spesifieke fraksies van die oorspronklike IPPK, herkombinering van die oorblywende fraksies, en die studie van die eienskappe van hierdie herkombineerde polimeriese materiale. Daar is gevind dat sommige van die eienskappe van die herkombineerde materiale daadwerklik verskil van die oorspronklike materiaal, en dat die verskille direk verband hou met die spesifieke fraksie wat uit die oorspronklike materiaal verwyder is. Die mate van fase-skeiding asook die kristal-morfologie van die herkombineerde materiaal het opmerklik verskil van die oorspronklike. Tydens die studie is n effektiewe manier ontwikkel om die materiale te vlek vir transmissie elektron-mikroskopie (TEM). Verder is daar ‘n verband tussen die resultate verkry deur Fourier Transform infrarooi spektroskopie (FTIS) en die verkry met TEM en skandeer elektron mikroskopie (SEM) vasgestel. Die verwantskap tussen FTIS en fase-skeiding is tot dusver nie in die wetenskaplike literatuur vermeld nie. Meer spesifiek is daar gevind dat absorbsie-bande sigbaar by 1100 cm-1 en 1080 cm-1 in die FTIS spektra ‘n aanduiding van fase skeiding kan wees. Dit was verder vasgestel dat spesifieke kopolimeer fraksies wat teenwoordig is in die oorspronklike IPPK, nie alleen die morfologie van die materiaal beinvloed nie, maar ook die hardheid en impak-weerstand van die materiaal.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/2435
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