Abstract
Growing environmental concerns related to the use of
synthetic non-biodegradable polymers in the packaging
industry have led to the need for new, especially
bio-based, materials. Currently, petroleum-based
synthetic polymers are widely used due to their
relatively low cost and high performance. Biodegradable
plastics and fibre-based materials have been proposed as
a solution to the waste problems related to these
synthetic polymers. Fibre-based packaging materials have
many advantages over their non-biodegradable competitors,
such as stiffness vs. weight ratio and recyclability.
However, poor barrier properties and sensitivity to
moisture are the main challenges restricting their use.
Application of a thin coating layer is one way to
overcome these problems and to improve the barrier
properties of such materials.
Atomic layer deposition (ALD) is a well suited technique
for depositing thin inorganic coatings onto
temperature-sensitive materials such as polymer-coated
boards and papers and polymer films. In the present work,
thin and highly uniform Al2O3 coatings were deposited at
relatively low temperatures of 80, 100 and 130 °C onto
various bio-based polymeric materials employing the ALD
technique. The study demonstrates that a 25-nm-thick
ALD-grown Al2O3 coating significantly enhances the oxygen
and water vapour barrier performance of these materials.
Promising barrier properties were obtained with
polylactide-coated board, hemicellulose-coated board as
well as various biopolymer (polylactide, pectin and
nanofibrillated cellulose) films after coating with a
25-nm-thick Al2O3 layer.
Thin Al2O3 coatings can improve the properties of
biopolymers, enabling the use of these renewable polymers
in the production of high-performance materials for
demanding food and pharmaceutical packaging applications.
The future roll-to-roll ALD technology for coating
polymers with inorganic thin films will increase the
industrial potential of these materials and could lead to
further opportunities for their commercialization.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 18 Nov 2011 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 978-951-38-7750-7 |
Electronic ISBNs | 978-951-38-7751-4 |
Publication status | Published - 2011 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- atomic layer deposition
- aluminium oxide
- thin film
- barrier
- biopolymer
- packaging material