Carboxylated nanocellulose/poly(ethylene oxide) composite films as solid-solid phase-change materials for thermal...

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Poly(ethylene oxide) (PEO) is a versatile polymer with potential applications in energy storage.
• Improving the mechanical and thermal properties of PEO is crucial for advanced material development.
• Cellulose nanofibrils (CNFs) offer excellent mechanical properties and a high surface area.

Purpose of the Study:

• To investigate the effect of incorporating surface-carboxylated cellulose nanofibrils (CNFs) into a poly(ethylene oxide) (PEO) matrix.
• To evaluate the structural, mechanical, and thermal properties of the resulting composite films.
• To explore the potential of these composite films as solid-solid phase-change materials for energy storage.

Main Methods:

• Composite films were prepared by mixing aqueous dispersions of CNFs and PEO solutions.
• Films were fabricated using casting and drying techniques with varying CNF content (0%-20%).
• Characterization included optical transparency, crystallinity analysis, mechanical testing (Young's modulus, tensile strength), and thermal expansion measurements.

Main Results:

• The 20% CNF/PEO composite film exhibited transparency, unlike the translucent pure PEO film.
• CNF addition decreased PEO crystallinity and crystal size but significantly enhanced Young's modulus (0.2 to 2.4 GPa) and tensile strength (6.1 to 86 MPa).
• Composite films maintained clear melting/crystallization temperatures and showed reduced thermal expansion above PEO's melting point.

Conclusions:

• The incorporation of CNFs into PEO significantly improves the mechanical properties and dimensional stability of the composite films.
• The CNF/PEO composite films demonstrate promising characteristics for solid-solid phase-change materials in energy storage.
• These materials offer a pathway to developing high-performance, stable energy storage solutions.