Lipase-catalyzed laurate esterification of cellulose nanocrystals and their use as reinforcement in PLA composites

Cellulose nanocrystals (CNCs) were surface-modified using immobilized lipase (Novozyme 435) to catalyze the formation of laurate ester groups on the CNC surface and thus facilitate homogeneous dispersion within a poly(lactic acid) (PLA) matrix. Results of dynamic contact angle measurement revealed t...

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Bibliographic Details
Published in:Cellulose (London) 2020-07, Vol.27 (11), p.6263-6273
Main Authors: Yin, Yuanyuan, Lucia, Lucian A., Pal, Lokendra, Jiang, Xue, Hubbe, Martin A.
Format: Article
Language:English
Subjects:
Bioorganic Chemistry
Breakage
Cellulose
Cellulose esters
Ceramics
Chemistry
Chemistry and Materials Science
Composites
Contact angle
Crystallization
Dispersion
Elongation
Esterification
Glass
Hydrophobicity
Lipase
Mechanical properties
Nanocrystals
Natural Materials
NMR
Nuclear magnetic resonance
Organic Chemistry
Original Research
Photomicrographs
Physical Chemistry
Polylactic acid
Polymer Sciences
Structural stability
Sustainable Development
Tensile strength
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Summary:Cellulose nanocrystals (CNCs) were surface-modified using immobilized lipase (Novozyme 435) to catalyze the formation of laurate ester groups on the CNC surface and thus facilitate homogeneous dispersion within a poly(lactic acid) (PLA) matrix. Results of dynamic contact angle measurement revealed that the modified CNCs (CNC-LAA) presented greater hydrophobicity than their CNC controls. FT-IR, 13 C-NMR, XRD, and TGA were used to characterize the structure and stability of the CNCs before and after modification. PLA reinforced with the modified CNCs were prepared, and the effect on mechanical properties was studied. SEM micrographs suggested uniform dispersion of modified CNCs throughout the PLA matrix at a maximum 1 wt% loading, which was found to be the optimal loading level. The CNC-LAA were able to achieve a 0.4 maximum degree of substitution. DSC indicated enhanced crystallization of PLA chains due to the inclusion of CNC-LAA, indicating that the nanofillers behaved as nucleating agents and also revealed improved compatibility. Tensile strength tests showed slightly improved mechanical properties for breaking strength and elongation at breakage.
ISSN:0969-0239
1572-882X
DOI:10.1007/s10570-020-03225-3