Packaging is one of the major fields for plastic materials, with extruded polypropylene (PP) sheet widely used in the production of thin gauge tubs and containers for the food and beverage industry using the thermoforming process. In an increasingly competitive market understanding the fundamental material properties and the effect of thermoforming process settings can help a company deliver material and efficiency savings allowing them to reduce production, manufacturing and development costs. The main aim of this work was to advance the practical understanding of the processing of PP for packaging applications, by linking the fundamental material behaviour to the industrial thin gauge thermoforming process. During this work investigations were carried out into the basic properties of commercial grades of PP and the affect of blending on material and end container properties. The effect of extrusion and thermoforming process conditions on end container properties were also investigated along with large strain mechanical stretching using lab equipment capable of replicating the industrial process settings. Investigations into both the affect of extrusion settings and thermoforming settings have shown that the PP material grade selected can have a greater effect than changes in process settings; with changes in settings having a different degree of effect on the different PP material grades. Therefore it is important for a thermoformer not just to consider the material type but the material grade or percentage blend during product development. This work has also highlighted the fact that complex blends can be created everyday in the industrial thin gauge thermoforming process and these blends will greatly affect t,he behaviour of the material during processing, and the end container properties. Overall the work demonstrates how susceptible PP is to changes in blends and processing conditions and will be particularly relevant to the developing recycled materials area.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:675461 |
| Date | January 2014 |
| Creators | McConville, Eileen |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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