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RHEOLOGICAL CHARACTERIZATION OF THERMOPLASTIC COMPONENTS EVAK FOR FORMULATION OF ADHESIVES

Autoři: Šiška Bedřich | Machač Ivan | Balcar Miroslav | Vrána Jiří

Rok: 2012

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

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Jazyk	Název	Abstrakt	Klíčová slova
eng	RHEOLOGICAL CHARACTERIZATION OF THERMOPLASTIC COMPONENTS EVAK FOR FORMULATION OF ADHESIVES	In this contribution, the results are presented of measurements of rheological behaviour of three EVAK components, differing by their molecular weight, designated according to their melt index as EVAK-25, EVAK-150, and EVAK-400. Viscoelastic properties for EVAK components in the solid state were examined using DMA. Dynamic temperature sweeps were carried out in the temperature range from -50 to 70 oC. The steady shear and dynamic properties of the molten components were measured using Haake MARS rheometer in the temperature range of 140 −180 oC. The values of the glass transition temperature Tg , which were determined from DMA measurements, are about - 15 oC for all components tested. The melts have a constant viscosity at low shear rates , at the higher values of shear rates(more than 1 – 10 s-1) behave as shear thinning fluids. They additionally show a thixotropic behaviour. The viscosity, degree of shear thinning and thixotropy decrease along with the increasing values of the melt index and temperature. From the oscillatory tests, the storage modulus G ́, loss modulus G ́ ́, and complex viscosity were evaluated. At lower values of frequency, loss modulus prevails, which predicates that the wetting and adhesive flow can be sufficient to form a good contact to the substrate. Along with the increasing frequency, G ́ increases faster in comparison with G ́ ́ and the shear resistance heightens. The results of creep and recovery tests document that the polymer melts exhibit only insignificant degree of linear elasticity.	rheology;thermoplastic components; EVAK; adhesives

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