Significant growth is predicted for the bi-axially oriented polyethylene terephthalate films market, in part due to increased number of applications. Besides reduced manufacturing costs and improved material properties Direct Extrusion Addition technology offers faster new product development. Critical to success in retrofitting the technology onto existing film lines is achieving the differing dispersion requirements of flame retardant, opaque and handleable films within the constraints of the film line operating window and conventional equipment. The optimum conditions for process parameters, the role of material properties and screw design required in delivering the desired level of dispersion were identified experimentally. Fundamental understanding of average shear rate/stress coupled with characterisation of mixing via film surface analysis and/or cross-sectional analysis of pellets (shown to adequately describe the filler dispersion in films) yielded promising relationships between the total strain and the degree of dispersion achieved. The results highlighted the importance of screw speed and the minimal impact of the screw configuration. A compromise between mechanically induced chain scission led viscosity reduction and high shear required for mixing was identified. Through the development/understanding of the fundamental principles and processing requirements for good dispersion, the basis for a design guide has been developed for the technology.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:768316 |
| Date | January 2018 |
| Creators | Stratiychuk-Dear, Dmytro |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/8821/ |
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