Evaluation of Antifreeze Coatings to prevent icing on Arctic Offshore Structures
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Icing of operating structures in the Arctic areas causes difficulties for ships and offshore drilling units. The large amount of accreted ice on these structures can make the ship turn over, and makes the work both challenging and dangerous. The scope of this master thesis is to investigate how icing on such structures can be prevented, focusing on developing a coating based on an antifreeze compound. Through the thesis, a summary of adhesion aspects, polymeric materials and antifreeze properties are presented. Additionally, several experiments, both qualitative and quantitative, are performed. The experimental section presents epoxy, glycerol, propylene glycol and polyvinylpyrrolidone (PVP), and how they can be implemented as an antifreeze coating. An applicable coating should be able to prevent sea water from freezing on it, not by making the coating hydrophobic, but by preventing an interfacial contact between substrate and sea spray ice. The epoxy gives as well as no protection against icing, and is difficult to implement with an antifreeze material. Pure antifreeze has excellent antifreeze properties, but offer no adhesive strength with the surface to be coated. A mixture of PVP and glycerol proved to give the most promising result. The relationship between adhesive strength and antifreeze property depends on the weight percent of the PVP, and a high PVP amount increases the adhesive strength. Several PVP-G coatings are presented, and all of these are evaluated with a single lap shear test. The lowest adhesive ice strength obtained from the presented mixtures, is 0.0114±0.006 MPa.