Mechanical Reinforcement of Thermoplastic Polyurethane Nanocomposites by Surface‐Modified Nanocellulose

Abstract

Utilization of biodegradable nanofillers is an emerging approach for the sustainable development of polymer composites. Among numerous green nanofillers, nanocellulose has garnered significant attention because of its abundance, high mechanical strength, and reinforcing capability. However, the intrinsic hydrophilicity of nanocellulose often restricts its homogeneous dispersion in the hydrophobic polymer matrix, resulting in a poor reinforcement effect. In this study, a simple surface modification of cellulose nanofibrils (CNFs) using small hydrophobic molecules is presented. Hydrophobic-modified CNFs have better solubility in organic solvents and exhibit homogeneous dispersion in a thermoplastic polyurethane (TPU) matrix. The molecular interaction between CNFs and the hard/soft segments (HS/SS) of TPU induces surface-mediated crystallization with improved microphase separation of SS and HS. By bridging multiple HS and SS microdomains, hydrophobic-modified CNFs improve the tensile modulus and ultimate tensile strength of the polymer nanocomposites. On the other hand, unmodified CNFs are strongly aggregated in the TPU matrix, which restricts the mechanical reinforcement. These results demonstrate that surface modification of nanocelluloses can engineer their dispersion state and interfacial interaction with matrix polymers, which are crucial for the mechanical reinforcement of polymer nanocomposites.

High-Strength Polyurethane Composite Film Reinforced by Cellulose Nanocrystals

“…Cellulose is considered as a promising chemical raw material in the future due to its wide source, easy modification, and superior biocompatibility and biodegradability. − Cellulose nanocrystals (CNCs) extracted from cellulose retain the advantages of cellulose, such as high crystallinity, modulus, and strength characteristics. − In recent years, many researchers have chosen cellulose as the reinforcing phase in composite materials. Meng et al presented poly­(vinyl alcohol) (PVA)/CNC composites with excellent mechanical and antibacterial properties by introducing CNC-based nanofillers .…”

Quantification Characterization of Hierarchical Structure of Polyurethane by Advanced AFM and X-ray Techniques

“…Specifically, the HS has a high glass-transition temperature ( T g ), which imparts rigidity to the material, while the SS has a lower T g , contributing to its elasticity. The HS is generated through the chemical reaction between isocyanate and small molecular diols. , In contrast, the SS is typically composed of polyether or polyester polyol with molecular weights ranging from 1000 to 3000 g/mol. , These inherent structural characteristics of PU give rise to a wide range of versatile properties, making it a highly desirable material in various industries.…”