Thermoplastic polyurethane-cellulose nanocomposite for transparent armour: Characterisation of adhesion and thermal aging

Environmental degradation of transparent thermoplastic polyurethane (TPU) is an issue of growing concern. Measured increased in the mechanical properties of nano-reinforced TPUs have been reported, however, limited research is available regarding their adhesive properties and resistance to environmental aging. By incorporating cellulose nanocrystals (CNCs) into a TPU via planetary ball milling, an increase to both the mechanical and adhesive properties was obtained. The TPU/CNC nanocomposite showed bond integrity and lap shear strengths were increased by 34% and 25% respectively relative to the unmodified nanocomposite, and further improvements in mechanical performance were seen. The TPU/CNC nanocomposite showed higher melting temperature and increased melting enthalpy indicating improved thermal aging resistance. The restriction of TPU segments and changes in chemical bond state and crystallinity were identified as key mechanisms driving performance improvements.