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| Titel: |
MATHEMATICAL MODELING AND THE ESTIMATION OF PARAMETERS FOR THE MELT VISCOSITY OF POLYAMIDES |
| Auteur: |
Sadiku, E. R. Swanepoel, E. Sanderson, R. D. |
| Verschenen in: |
International journal of polymeric materials |
| Paginering: | Jaargang 52 (2003) nr. 5 pagina's 431-458 |
| Jaar: |
2003-05 |
| Inhoud: |
Capillary rheometry data of a range of commercial polyamide engineering materials was obtained from a mould-flow analysis material database, from which melt viscosity data was obtained at different temperatures, which made comparison of the viscosities difficult. In an attempt to make a reasonable comparison between the melt viscosities of the various polyamide materials at different temperatures, it was necessary to obtain the mathematical functions which describe the relationships between: (i) the melt viscosity and the shear rate, (ii) the melt viscosity and temperature and (iii) the melt viscosity and the combined effect of the shear rate and temperature of each of the polyamides studied. Therefore, melt viscosity was modelled as a function of shear rate at the three temperatures (275°C, 295°C and 315°C), at which the viscosities were determined. The function obtained represented smoothed versions of the experimental data, eliminating the experimental noise and enabling the generation of melt viscosity data at the six different shear rates of the original data. It was established that the melt viscosity as a function of shear rate at constant temperature, in the shear rate range 500-700 s -1 , is incorrectly described by the Ostwald-de-Waele's model, \eta_{\rm T}={\rm f}({\dot \gamma})={\rm K}({\dot \gamma})^{({\rm n}-1)} , while the melt viscosity of the polyamides studied, as a function of temperature, is correctly described by the model \eta_{\dot \gamma}={\rm g}{(\rm T)}={\rm Pe}^{\left (\rm {QT/R}\right )} . But the response-surface melt viscosity is effectively described as a function of both shear rate and temperature by the model: \eta=\vert {\dot \gamma}\vert^{(\rm n-1)}{\rm Ae}^{(\rm ET/R)} . The parameters A, E and n are highly interrelated as they all influence the average melt viscosity. All are temperature sensitive and also, to some degree, shear sensitive. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 16 van 37 gevonden artikelen
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