Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
De Goede, E., Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa; Mallon, P., Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa; Pasch, H., Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
TREF and SEC-FTIR were combined for the first time to characterise a commercial ICPP. This off-line coupling proved to be especially useful for the characterisation of fractions of co-eluting non-identical components, exhibiting bimodal molecular weight distributions. Within these fractions the chemical composition distribution across the molecular weight curve indicated the presence of EPC within the lower elution volume, high molecular weight distribution within the bimodal curve, while PP homopolymer was present across the high elution volume, low-molecular-weight distribution. The distribution of ethylene and propylene sequence crystallinity across the molecular weight distribution indicated the presence of both crystalline ethylene and propylene sequences across the EPC component, while only crystalline PP was detected within the component characterised as PP homopolymer. These results were used to characterise the melt behaviour of TREF fractions measured by DSC, especially those of the above-mentioned fractions containing co-eluting EPC and iPP. The melt endotherm present at lower temperature within the 60-100 8C fractions was assigned to the melting of ethylene sequences present within the EPC component while the endotherm at higher temperature was representative of the melting of propylene sequences present within bothEPCandiPP.Thecombination of TREFandSEC-FTIRhadproven to be one of the simplest, fastest ways of characterising ICPPs. A single SEC-FTIR analysis of each TREF fraction allows for the simultaneous identification of constituents as well as the determination of ethyleneand propylene crystallinity as a function of molecular weight. This approach replaces analytical procedures where TREF analysis would have to be followed by additional steps of both FTIR and DSC analyses to obtain information of a similar nature. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Analytical procedure; Bimodal molecular weight distribution; Characterisation; Chemical composition distributions; Crystallinities; Elution volumes; FTIR; FTIR analysis; High molecular weight; Higher temperatures; Homopolymers; Identical components; Low molecular weight; Poly(propylene) copolymers; Propylene sequences; Simultaneous identification; Temperature-rising elution; Temperature-rising elution fractionation; Copolymerization; Crystalline materials; Ethylene; Fourier transform infrared spectroscopy; Gel permeation chromatography; Molecular weight distribution; Plastic products; Polypropylenes; Size exclusion chromatography; Weighing; Propylene