Nanocelluloses Reinforced Bio-Waterborne Polyurethane

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Waterborne polyurethanes (WBPU) are versatile polymers with growing applications.
• Bio-based reinforcements offer sustainable alternatives to traditional fillers.
• Cellulose-based nanomaterials, including cellulose nanocrystals (CNCs) and bacterial cellulose (BC), show promise for polymer reinforcement.

Purpose of the Study:

• To investigate the effects of CNCs and BC as nano-reinforcements on the properties of castor oil-based WBPU films.
• To compare the performance of WBPU composites reinforced with CNCs versus BC.
• To understand the structure-property relationships influenced by these nanocellulose reinforcements.

Main Methods:

• Preparation of WBPU/BC composite via membrane impregnation and drying.
• Preparation of WBPU/CNC composite via casting.
• Characterization using thermal gravimetric analysis, FTIR, FESEM, DMA, DSC, contact angle, and water absorption tests.

Main Results:

• Both CNCs and BC dispersed well in WBPU, yielding optically transparent composites.
• Incorporation of nanoreinforcements increased the storage modulus of WBPU above its glass transition temperature.
• BC-reinforced composites exhibited slightly higher thermal stability and maintained structural integrity in water compared to CNC composites.

Conclusions:

• Bacterial cellulose (BC) is a superior nano-reinforcement for castor oil-based waterborne polyurethane (WBPU) compared to cellulose nanocrystals (CNCs).
• The enhanced properties of BC composites are attributed to BC's high thermal stability and unique 3D interconnected morphology.
• These findings highlight the potential of BC for developing advanced, durable, and sustainable WBPU-based materials.