Understanding Toughness in Bioinspired Cellulose Nanofibril/Polymer Nanocomposites
| Autor: | Baolei Zhu, Francisco Lossada, Tobias Rudolph, Andreas Walther, Alejandro J. Benítez |
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| Rok vydání: | 2016 |
| Předmět: |
Toughness
Materials science Polymers and Plastics Polymer nanocomposite Polymers Nanofibers Bioengineering 02 engineering and technology 010402 general chemistry 01 natural sciences Nanocomposites Biomaterials chemistry.chemical_compound Tensile Strength Polymer chemistry Ultimate tensile strength Materials Chemistry Copolymer Transition Temperature Cellulose Composite material chemistry.chemical_classification Nanocomposite Water Polymer 021001 nanoscience & nanotechnology 0104 chemical sciences chemistry Glass 0210 nano-technology Glass transition |
| Zdroj: | Biomacromolecules. 17(7) |
| ISSN: | 1526-4602 |
| Popis: | Cellulose nanofibrils (CNFs) are considered next generation, renewable reinforcements for sustainable, high-performance bioinspired nanocomposites uniting high stiffness, strength and toughness. However, the challenges associated with making well-defined CNF/polymer nanopaper hybrid structures with well-controlled polymer properties have so far hampered to deduce a quantitative picture of the mechanical properties space and deformation mechanisms, and limits the ability to tune and control the mechanical properties by rational design criteria. Here, we discuss detailed insights on how the thermo-mechanical properties of tailor-made copolymers govern the tensile properties in bioinspired CNF/polymer settings, hence at high fractions of reinforcements and under nanoconfinement conditions for the polymers. To this end, we synthesize a series of fully water-soluble and nonionic copolymers, whose glass transition temperatures (Tg) are varied from -60 to 130 °C. We demonstrate that well-defined polymer-coated core/shell nanofibrils form at intermediate stages and that well-defined nanopaper structures with tunable nanostructure arise. The systematic correlation between the thermal transitions in the (co)polymers, as well as its fraction, on the mechanical properties and deformation mechanisms of the nanocomposites is underscored by tensile tests, SEM imaging of fracture surfaces and dynamic mechanical analysis. An optimum toughness is obtained for copolymers with a Tg close to the testing temperature, where the soft phase possesses the best combination of high molecular mobility and cohesive strength. New deformation modes are activated for the toughest compositions. Our study establishes quantitative structure/property relationships in CNF/(co)polymer nanopapers and opens the design space for future, rational molecular engineering using reversible supramolecular bonds or covalent cross-linking. |
| Databáze: | OpenAIRE |
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