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Papers are coated in order to improve the properties of the surface and/or to include new functionalities like barriers for oxygen and/or water vapour. A coating formulation contains a high number of components, some of which are mineral based and others are manufactured from petroleum. Sustainability is one of the most important issues today and research aimed for new materials based on renewable sources to replace traditional oil based products is important.
This project aims to evaluate two new materials in paper coating. One is nanocellulose, a new nano-sized material that is processed from cellulose. Films made from this material have shown good oxygen barrier properties and high strength. Thus it is interesting to examine properties of coating layers containing this material in combination with minerals. This approach will exclude petroleum based latex binder from the coating formulation. The other material is PLA latex. PLA stands for polylactic acid and is a polyester manufactured from renewable materials, e.g. corn. Both nanocellulose and PLA are fairly polar materials that will affect the surface chemistry of the final material. Thus, the project will include a comprehensive study on the surface chemistry and adhesion properties of the produced films.
Coating colours containing mineral pigments (e.g. calcium carbonate, kaolin clay, talk), thickener (e.g. carboxymethyl cellulose, polyvinyl alcohol) and nanocellulose and/or PLA-latex and possibly also other components (e.g. water borne alkyds to control the water wettability) will be prepared. The colours will be characterized with respect to water retention and rheology.
Coating layers will be made from the colours prepared according to the paragraph above. A rod coating technique will be used. Tentative evaluations and characterizations of the coating layer are:
• Pore structure using mercury porosimetry,
• surface energy using contact angle measurements,
• absorption of water using MicroDAT, a technique that follow the absorption of micro drops,
• strength using picking test or tensile strength test,
• adhesion to polyolefines, e.g. polyethylene,
• permeability of water vapour and oxygen.
The project will be concluded with an analysis of the possibilities to use nanocellulose and PLA-latex in coating applications.
The candidate should preferably be a last-year student in suitable M.Sc. program in chemistry or chemical engineering.
Contact at Innventia
Interested candidates should contact:
Göran Ström, 08-676 73 09, [email protected] or Christian Aulin, 08-676 72 60, [email protected] for further information.
Informationen om uppsatsförslag är hämtad från Nationella Exjobb-poolen.