Protein-mediated interfacial adhesion in composites of cellulose nanofibrils and polylactide: Enhanced toughness towards material development

Alexey Khakalo, Ilari Filpponen, Orlando J. Rojas

    Research output: Contribution to journalArticleScientificpeer-review

    21 Citations (Scopus)


    The role of animal protein, casein, as compatibilizer and eco-friendly dispersant in composites comprising cellulose nanofibrils (CNF) and polylactic acid (PLA) was investigated. The effect of casein-mediated surface modification of PLA was validated with dynamic adhesion experiments that considered the contact area according to JKR approximation. In fact, a remarkable increase by ∼50% in the work of adhesion between CNF and PLA was observed after casein adsorption. It is likely that the improved adhesion gave rise to an enhanced dispersion of CNF and PLA within the composite matrix. Moreover, the mechanical properties of the respective nanocomposites were significantly improved. When compared to protein-free CNF/PLA nanocomposites, the systems containing casein indicated an enhanced extensibility (by 130%) and tensile toughness (by 60%) whereas tensile strength and Young's modulus were improved to a limited extent (6 and 12%, respectively). Finally, it is demonstrated that the surface modification of PLA with casein improves the compatibility between CNF and PLA, which is a prerequisite for the feasible preparation of 3D shaped cellulose-based packaging materials by direct thermoforming.
    Original languageEnglish
    Pages (from-to)145-151
    JournalComposites Science and Technology
    Publication statusPublished - 26 May 2018
    MoE publication typeA1 Journal article-refereed


    This work was a part of ACel program of the Finnish Bioeconomy Cluster (FIBIC LTD) and it was financially supported by the Finnish Funding Agency for Technology and Innovation (TEKES) . The authors also acknowledge support from the Academy of Finland's Centres of Excellence Programme “Molecular Engineering of Biosynthetic Hybrid Materials Research”, HYBER (2014–2019) and Aalto University Nanomicroscopy Center (Aalto-NMC) . We are also thankful to Ritva Kivelä for AFM imaging.


    • Adhesion
    • Composites
    • Nanofibrillated cellulose
    • Polylactide
    • Proteins


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