TY - THES

T1 - Rheological characterisation of polymer melts on an injection moulding machine using a new slit die measurement system

AU - Selvasankar, Ramesh Kumar

N1 - embargoed until null

PY - 2008

Y1 - 2008

N2 - Determination of the polymer melts behaviour under the conditions of temperature and shear rate are very important for the accurate flow simulation. The reliability of the simulation results mainly dependent on the rheological characteristics of the polymers. The rheological characterisation is usually carried out in conventional capillary rheometer, where the measurable shear rate range is between 100 1/s and 100000 1/s. But the shear rates experienced by the melt during the injection moulding of parts with very small dimensions (micro sized) may exceed 1000000 1/s, which is out of range of conventional capillary rheometer to characterise. For the rheological characterisation of polymer melts by high shear rates under real life scenario, a new injection moulding machine rheometer with interchangeable slit die inserts have been developed at the Institute of Plastics Processing, as a part of the EU-Collective Research Projects (Pro4Plast) "New product development guidance systems (PGDS) for complex injection moulded plastic parts by enhanced injection moulding simulation and material data measurement applicable by SMEs". During the injection process the pressure loss and the increase in the melt temperature along the flow length were measured. By varying the volume flow rate, different shear rates have been achieved. With this technique, a Polypropylene material type HG313MO has been characterised at 3 temperatures. The measured wall temperature was found to be 80°C higher than the set temperature due to shear heating and hence there was an increase in the melt temperature, at very high flow rates. This temperature increase has been corrected during the viscosity calculation. For calculating the materials rheological data a calculation program has been written in Excel-VBA. Also the viscosity measurements have been performed in the conventional high pressure capillary rheometer and cone and plate rheometer. The rheological data produced by the injection moulding machine rheometer and commercial high pressure capillary rheometer has been compared.

AB - Determination of the polymer melts behaviour under the conditions of temperature and shear rate are very important for the accurate flow simulation. The reliability of the simulation results mainly dependent on the rheological characteristics of the polymers. The rheological characterisation is usually carried out in conventional capillary rheometer, where the measurable shear rate range is between 100 1/s and 100000 1/s. But the shear rates experienced by the melt during the injection moulding of parts with very small dimensions (micro sized) may exceed 1000000 1/s, which is out of range of conventional capillary rheometer to characterise. For the rheological characterisation of polymer melts by high shear rates under real life scenario, a new injection moulding machine rheometer with interchangeable slit die inserts have been developed at the Institute of Plastics Processing, as a part of the EU-Collective Research Projects (Pro4Plast) "New product development guidance systems (PGDS) for complex injection moulded plastic parts by enhanced injection moulding simulation and material data measurement applicable by SMEs". During the injection process the pressure loss and the increase in the melt temperature along the flow length were measured. By varying the volume flow rate, different shear rates have been achieved. With this technique, a Polypropylene material type HG313MO has been characterised at 3 temperatures. The measured wall temperature was found to be 80°C higher than the set temperature due to shear heating and hence there was an increase in the melt temperature, at very high flow rates. This temperature increase has been corrected during the viscosity calculation. For calculating the materials rheological data a calculation program has been written in Excel-VBA. Also the viscosity measurements have been performed in the conventional high pressure capillary rheometer and cone and plate rheometer. The rheological data produced by the injection moulding machine rheometer and commercial high pressure capillary rheometer has been compared.

KW - Rheologie Viskosität Spritzgießen Schlitzdüse Hochdruckkapillarrheometer Dissipationserwärmung

KW - rheology viscosity injection moulding slit die high pressure capillary rheometer shear heating

M3 - Master's Thesis

ER -