Abstract
An experimental study into paraffin wax (PW) and ethylene vinyl acetate (EVA-28) blends has been undertaken to investigate the potential for their use as carrier vehicles for ceramic injection moulding applications. Carrier systems are critical for the fabrication of this type of moulded component; making their properties at all stages of the process of great importance.
PW and EVA-28, in most circumstances, combine to form stable homogeneous blends, which experience relatively small changes in the melting and solidification phase transition behaviour. However, these blends exhibit notable viscosity shifts and flexural strength performance changes with increasing EVA-28 content.
The melt flow behaviour of the blends at shear rates of 100 s-1 varies from 0.01 Pa.s for PW to 10 Pa.s for the composition by weight of 50 % PW and 50 % EVA-28, which literature suggests is the upper limit of viscosities for successful carrier systems. All PW/EVA-28 blends experience shear thinning behaviour with increasing shear rate, which can be modelled with reasonable accuracy using the Cross and Carreau models. Increasing the EVA-28 content in a blend causes the initiation of shear thinning at progressively lower shear rates and also forms a blend with an increasing elastic character at typical injection temperature. Yield stress is not developed for blends containing less than fifty weight percent EVA-28.
The addition of EVA-28 significantly alters the mechanical properties of the blends, modifying the brittle nature of PW to develop increasing flexible and plastic properties. Although with less than twenty-five weight percent EVA-28 in a blend fracture failure still results, greater EVA-28 content represses the failure mechanisms developing increasing degrees of plastic deformation.
PW and EVA-28, in most circumstances, combine to form stable homogeneous blends, which experience relatively small changes in the melting and solidification phase transition behaviour. However, these blends exhibit notable viscosity shifts and flexural strength performance changes with increasing EVA-28 content.
The melt flow behaviour of the blends at shear rates of 100 s-1 varies from 0.01 Pa.s for PW to 10 Pa.s for the composition by weight of 50 % PW and 50 % EVA-28, which literature suggests is the upper limit of viscosities for successful carrier systems. All PW/EVA-28 blends experience shear thinning behaviour with increasing shear rate, which can be modelled with reasonable accuracy using the Cross and Carreau models. Increasing the EVA-28 content in a blend causes the initiation of shear thinning at progressively lower shear rates and also forms a blend with an increasing elastic character at typical injection temperature. Yield stress is not developed for blends containing less than fifty weight percent EVA-28.
The addition of EVA-28 significantly alters the mechanical properties of the blends, modifying the brittle nature of PW to develop increasing flexible and plastic properties. Although with less than twenty-five weight percent EVA-28 in a blend fracture failure still results, greater EVA-28 content represses the failure mechanisms developing increasing degrees of plastic deformation.
| Original language | English |
|---|---|
| Journal | Polymer - Plastics Technology and Engineering |
| Early online date | 30 Jan 2016 |
| DOIs | |
| Publication status | E-pub ahead of print - 30 Jan 2016 |
Keywords
- PW/EVA blends
- Organic carrier system
- Particle injection moulding