Effect of rheology and crystallinity on processing and barrier properties of PHA
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Innovative and sustainable chemical engineering (MPISC), MSc
Publicerad
2023
Författare
Siva Kumar, Amit Kumar
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Plastic pollution is one of the major problems that the world is facing at present.
Different industrial sectors contribute to this and the packaging sector is one of
the main contributors. According to the statistics, the packaging sector alone contributes
to 60% of the total plastic pollution. This creates the need for the packaging
industry to become more sustainable and produce more environmentally friendly
products. There are various types of packaging products and this thesis is focused
on food packaging. In food packaging a plastic layer is used to act as a barrier
against, for example, gases, such as oxygen and carbon dioxide, and sunlight, as
these can decrease the shelf life of the packaged food. However, the plastic film is
produced from fossil-based resources and is not biodegradable. The replacement of
the conventional plastic barriers with a bio-based polymer is one possible solution
to move towards more sustainable packaging materials. For this purpose, a class
of bio-based polymers named polyhydroxyalkanoates (PHAs) have been studied in
this project. Four different types of PHAs have been characterized using techniques
such as DSC, TGA, and DMA, among others. Rheological characteristics were
also studied to improve the PHA processing and coating onto paperboard at a pilot
scale. Additionally, water vapor barrier properties of the different PHA samples and
PHA-coated paperboard were measured and the effect of PHA molecular weight and
crystallinity on these was also assessed. From this study, it was observed that PHA
with higher molecular weight showed better performance in terms of mechanical
properties and barrier properties. Moreover, PHA crystallinity has also been shown
to play an important role in terms of barrier properties alongside molecular weight.
Regarding rheological properties, it was verified that PHA with higher molecular
weight has higher melt viscosity, which makes the material stable at higher temperatures
but at the same time, hinders the production of proper coating onto the
paper-board. For a better understanding of how PHA processing through extrusion
coating can be improved in practice, further studies are required, for instance, the
change of processing parameters and the compounding of PHA with other components/
polymers.
Beskrivning
Ämne/nyckelord
Packaging , polyhydroxyalkanoates , barrier properties , rheological properties , crystallinity , extrusion coating