Towards more sustainable materials for boat decking: Novel fillers for light-weighting and enhanced recyclability

Pittaway, Michael Donald (2023) Towards more sustainable materials for boat decking: Novel fillers for light-weighting and enhanced recyclability. Masters by Research thesis (MPhil), Manchester Metropolitan University.

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Abstract

In this study selected hollow fillers in several polymers and polymer blends have been evaluated for use in composite boat decking. Traditionally teak has been the material of choice for boat decking, but there are now concerns regarding sustainable management of this material. Synthetic polymers now dominate the market, due largely to easier installation and maintenance; with PVC being the polymer frequently used in boat decking. The decking takes the form of strips, rolls or prefabricated panels. A particular focus of recent development has been to enhance thermal insulation (reduce temperature underfoot) and lower the density of the material. Although hollow glass microspheres tend to be the material of choice to achieve these properties, they can be abrasive on processing equipment and difficult to recycle. Hence the focus of this work has centred on hollow calcium carbonate in PVC, because calcium carbonate is used as a filler throughout the PVC industry. The rationale is that end-of-life decking could be more easily close-loop recycled or, regrind directed to a wide-range of alternative PVC applications, thereby enhancing sustainability of the product. At present hollow calcium carbonate is not in widespread commercial production, therefore in this study hollow calcium carbonate was synthesised by templating with a cationic polymer (PDADMAC or PDDA) to direct 3D assembly of hollow structures. The influence of template concentration, mixing time and order of addition of components was evaluated. Both spherical and rhombohedral polymorphs of calcium carbonate were produced. The latter was incorporated in plasticised PVC at filler fractions of 15 wt.% and 24 wt.%. The performance of calcium carbonate was assessed against hollow glass filler in PVC. In addition, predictions using calculations based on volume fraction, for alternative fillers (e.g., cork and expanded microspheres), polymers (epoxy and polyester resins) and polymer blends (PVC/TPU, PVC/Nitrile rubber, PVC/CPE, PVC/CPVC, PE/CPE, PE/CPVC) were undertaken, with a view to optimising product performance.