Molecular weight distribution, impact on morphology, crystallinity and mechanical properties
(2018) KASM15 20181Centre for Analysis and Synthesis
- Abstract
- This master thesis is the result of cooperation between Lund University and Tetra Pak, performed by a student at Engineering Nanoscience, LTH. The aim is to explain how different molecular weights and molecular weight distribution of isotactic homo-polypropylene affect resulting properties. Examined properties are mechanical properties by tensile testing and tensile impact, shear viscosity by capillary rheometry and crystallinity by Differential Scanning Caliometry.
Aim was also to find good rheological measures for polydispersity, by comparing these measures of molecular weight distribution by Size Exclusion Chromatography. These rheological examinations were executed by use of oscillating rheometry sweeps at different temperatures and... (More) - This master thesis is the result of cooperation between Lund University and Tetra Pak, performed by a student at Engineering Nanoscience, LTH. The aim is to explain how different molecular weights and molecular weight distribution of isotactic homo-polypropylene affect resulting properties. Examined properties are mechanical properties by tensile testing and tensile impact, shear viscosity by capillary rheometry and crystallinity by Differential Scanning Caliometry.
Aim was also to find good rheological measures for polydispersity, by comparing these measures of molecular weight distribution by Size Exclusion Chromatography. These rheological examinations were executed by use of oscillating rheometry sweeps at different temperatures and calculations build upon equations found in literature.
The different types of polypropylene examined for mechanical properties were injection moulded. In injection moulding shear forces create an anisotropic resulting material, with higher orientation in the direction of shear. This was examined by testing the mechanical properties in different directions of injection moulded plates. The plates were stored after processing to examine if the properties vary during storage, up to 6 weeks. Scanning Electron Microscopy was utilised to analyse the different zones created by injection moulding in the cross section of the plates.
Findings were among other that molecular weight distribution strongly influence the mechanical properties, and that the mechanical properties vary widely with storage time after injection moulding. This variations over time is assumed to arise from post crystallisation and physical ageing. (Less) - Popular Abstract (Swedish)
- I dagens samhälle har vi en ofantligt hög konsumtion av förpackade drycker. För att ständigt förbättra kvalitén och korta ner produktionstid krävs en ständig utveckling av produkter. I applikationer för öppningsbarhet och skruvkorkar till förpackningar används bland annat plasten polypropen. Målet med studien som har gjorts har varit att undersöka hur plasten varierar i vissa utvalda egenskaper som går att relatera till öppningsbarhet, samt att undersöka egenskaper som påverkar processen för att tillverka korkarna.
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/8950170
- author
- Petersen, Malin LU
- supervisor
- organization
- course
- KASM15 20181
- year
- 2018
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Molecular weight, Molecular weight distribution, isotactic Polypropylene, polymer technology, polymerteknologi
- language
- English
- id
- 8950170
- date added to LUP
- 2018-06-20 14:14:30
- date last changed
- 2018-06-20 14:14:30
@misc{8950170,
abstract = {{This master thesis is the result of cooperation between Lund University and Tetra Pak, performed by a student at Engineering Nanoscience, LTH. The aim is to explain how different molecular weights and molecular weight distribution of isotactic homo-polypropylene affect resulting properties. Examined properties are mechanical properties by tensile testing and tensile impact, shear viscosity by capillary rheometry and crystallinity by Differential Scanning Caliometry.
Aim was also to find good rheological measures for polydispersity, by comparing these measures of molecular weight distribution by Size Exclusion Chromatography. These rheological examinations were executed by use of oscillating rheometry sweeps at different temperatures and calculations build upon equations found in literature.
The different types of polypropylene examined for mechanical properties were injection moulded. In injection moulding shear forces create an anisotropic resulting material, with higher orientation in the direction of shear. This was examined by testing the mechanical properties in different directions of injection moulded plates. The plates were stored after processing to examine if the properties vary during storage, up to 6 weeks. Scanning Electron Microscopy was utilised to analyse the different zones created by injection moulding in the cross section of the plates.
Findings were among other that molecular weight distribution strongly influence the mechanical properties, and that the mechanical properties vary widely with storage time after injection moulding. This variations over time is assumed to arise from post crystallisation and physical ageing.}},
author = {{Petersen, Malin}},
language = {{eng}},
note = {{Student Paper}},
title = {{Molecular weight distribution, impact on morphology, crystallinity and mechanical properties}},
year = {{2018}},
}