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Polyhydroxyalkanoate (PHA) biopolymers are emerging as attractive new sustainable polymers due to their true biodegradability and highly tuneable mechanical properties. However, despite significant investments, commercialisation barriers are hindering the capacity growth of PHA. In this work, we investigated the market potential for wood plastic composites (WPCs) based on PHAs. We considered the latest global production capacity of PHAs, estimated at 66,000 tonnes/year, and examined the implications of using PHAs for WPC production on the WPC market. Results indicate that a hypothetical usage of the current global PHA production for WPC manufacture would only represent the equivalent of 4.4% of the global WPC market, which is currently experiencing a 10.5% compounded annual growth rate. An economic assessment revealed that a wood-PHA composite as a drop-in alternative WPC product could cost as little as 37% of the cost of its neat PHA counterpart. Thus, WPCs with PHA offer a means to access benefits of PHA in engineering applications at reduced costs; however, further developments are required to improve strain at failure. The successful adoption of wood-PHA composites into the market is furthermore reliant on support from public sector to encourage biodegradable products where recycling is not a ready solution.

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There is increasing demand for synthetic bone scaffolds for bone tissue engineering as they can counter issues such as potential harvesting morbidity and restrictions in donor sites which hamper autologous bone grafts and also address the potential for disease transmission in the case of allografts. Due to their excellent biocompatibility, titanium scaffolds have great potential as bone graft substitutes as they can mimic the structure and properties of human cancellous bone. Here we report on a new thermoset bio-polymer which can act as a binder for Direct Ink Writing (DIW) of titanium artificial bone scaffolds. We demonstrate the use of the binder to manufacture porous titanium scaffolds with evenly distributed and highly interconnected pores ideal for orthopaedic applications. Due to their porous titanium structure, the scaffolds exhibit an effective Young's modulus similar to human cortical bone, alleviating undesirable stress-shielding effects, and possess superior strength. The biocompatibility of the scaffolds was investigated in vitro by cell viability and proliferation assays using human bone-marrow-derived Mesenchymal stem cells (hMSCs). The hMSCs displayed well-spread morphologies, well-organised F-actin and large vinculin complexes confirming their excellent biocompatibility. The vinculin regions had significantly larger Focal Adhesion (FA) area and equivalent FA numbers compared to that of tissue culture plate (TCP) controls, showing that the scaffolds can support cell viability and promote attachment. In conclusion, we have demonstrated the excellent potential of thermoset bio-polymer as a Direct Ink Writing ready inkjet binder for manufacture of porous titanium scaffolds for hard tissue engineering.