|
|
Effect of controlled degradation on the structure of high-impact polypropylene
Pragerová, Barbora ; Kratochvíla,, Jan (referee) ; CSc, Zdeněk Buráň, (advisor)
This thesis deals with the effect of controlled degradation on the structure of ethylene-propylene copolymers. The studied samples were produced in reactor as a heterophase mixture of homopolymer PP and~E/P copolymer on Ziegler-Natta catalysts. Two samples were degraded to a higher melt flow index using peroxides. These materials were then compared with reactor-prepared samples of the same melt flow index. In total, six samples of E/P copolymers were investigated, i.e. two series of three comparison samples each. For all samples, the melt flow index and the soluble fraction in xylene were determined (using the standard method according to XS-ISO 16152 and also XS-FIPA). Furthermore, in order to obtain detailed information about the structure of these materials, the granular samples were first subjected to TREF (Temperature rising elution fractionation. Each sample was separated into three fractions for which the molecular weight distribution was then determined by gel permeation chromatography (GPC). Nuclear magnetic resonance C13 NMR provided additional information. Changes in the structure of the E/P copolymers after controlled degradation were evaluated, and these degraded materials were also compared with their reactor equivalents produced directly with a higher melt flow index.
|
|
|
Effect of controlled degradation on the structure of high-impact polypropylene
Pragerová, Barbora ; Kratochvíla,, Jan (referee) ; CSc, Zdeněk Buráň, (advisor)
This thesis deals with the effect of controlled degradation on the structure of ethylene-propylene copolymers. The studied samples were produced in reactor as a heterophase mixture of homopolymer PP and~E/P copolymer on Ziegler-Natta catalysts. Two samples were degraded to a higher melt flow index using peroxides. These materials were then compared with reactor-prepared samples of the same melt flow index. In total, six samples of E/P copolymers were investigated, i.e. two series of three comparison samples each. For all samples, the melt flow index and the soluble fraction in xylene were determined (using the standard method according to XS-ISO 16152 and also XS-FIPA). Furthermore, in order to obtain detailed information about the structure of these materials, the granular samples were first subjected to TREF (Temperature rising elution fractionation. Each sample was separated into three fractions for which the molecular weight distribution was then determined by gel permeation chromatography (GPC). Nuclear magnetic resonance C13 NMR provided additional information. Changes in the structure of the E/P copolymers after controlled degradation were evaluated, and these degraded materials were also compared with their reactor equivalents produced directly with a higher melt flow index.
|
guest ::
