Vliv morfologie na deformační chování kopolymerů polyetylenu

The Effects of Morphology on the Yield Behaviour of Polyethylene Copolymers

conference paper

en

Several polyethylene copolymers from Czech production (which differed in the number of short change branches – SCB and molecular weight) were compared with two reference types of polyethylene copolymers from foreign production. Standard tensile specimens were prepared and the tensile test under different deformation speed (50, 5, 0.5 mm/min) and above glass transition temperature (Tg) was carried out. The results have shown changes in tensile yield stress in dependence on deformation speed and type of polyethylene copolymer. All materials types have shown non-linear behaviour above glass transition temperature. The WAXS analysis (wide-angle X-scattering) detected that, when the deformation speed was low, the macroscopic yield stress was affected from the re-orientation of crystalline lamellae. These facts could be also observed on the profile of the neck. The shape of the neck can tell us about heterogeneity of individual material types.

Práce se zabývá studiem deformačního chování několika druhů polyetylenových kopolymerů z České produkce a jejich srovnáním se zahraničními referenčními materiály. Byla provedena zkouška tahem při různých rychlostech zatěžování (50, 5, 0.5 mm/min). Dále byla provedena analýza metodou WAXS pro zjištění vlivu reorientace lamel na hodnoty materiálových charakteristik zjištěných z tahové zkoušky.

Several polyethylene copolymers from Czech production (which differed in the number of short change branches – SCB and molecular weight) were compared with two reference types of polyethylene copolymers from foreign production. Standard tensile specimens were prepared and the tensile test under different deformation speed (50, 5, 0.5 mm/min) and above glass transition temperature (Tg) was carried out. The results have shown changes in tensile yield stress in dependence on deformation speed and type of polyethylene copolymer. All materials types have shown non-linear behaviour above glass transition temperature. The WAXS analysis (wide-angle X-scattering) detected that, when the deformation speed was low, the macroscopic yield stress was affected from the re-orientation of crystalline lamellae. These facts could be also observed on the profile of the neck. The shape of the neck can tell us about heterogeneity of individual material types.

Polyethylene, Deformation behaviour

2005

20.09.2005

FSI VUT BRNO

80-214-2984-4

Sborník konference

263–266

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