Biopolymer cushioning foam for sustainable footwear applications

Overview

The footwear industry faces growing pressure to reduce its environmental impact due to the disposable nature of consumer footwear and resulting carbon footprint. This research addresses this challenge by developing high-performance cushioning foams from polyhydroxybutyrate (PHB), a biopolymer naturally produced by bacteria. PHB offers promising hydrophobic properties suitable for footwear applications, though its inherent brittleness has limited its commercial adoption. The project aims to engineer PHB-based composites with tailored mechanical properties capable of competing with conventional petroleum-derived materials such as polyurethane.

Technical specifications

Core approach:

• Melt processing of PHB alongside conventional polyurethane to establish baseline characteristics including compressive strength, density, mechanical strength, and water uptake
• Incorporation of sustainable plasticisers or secondary polymeric additives to modify and improve mechanical properties
• Density reduction through the addition of foaming agents to create a lightweight cushioning foam structure
• Injection moulding trials to evaluate scalability of the foamed composite biopolymer material
• Optional 3D printing trials using the developed biopolymer formulation

Key advantages:

• Bio-sourced and sustainable raw material base
• Hydrophobic properties suited to footwear applications
• Compatibility with established manufacturing processes such as melt processing and injection moulding

Technology readiness level

The research is at an early-to-mid stage of development. Initial baseline characterisation through melt processing of virgin PHB and polyurethane materials is underway. Subsequent phases will focus on additive incorporation, foaming, and injection moulding trials to assess scalability. The optional 3D printing exploration would further expand the material's potential applications. The research team brings decades of polymer engineering expertise and a strong track record in biopolymer development from sustainable sources.