Cellulose nanocrystal driven microphase separated nanocomposites: Enhanced mechanical performance and nanostructured morphology

Authors: ZHANG, JINLONG - LSU AGCENTER; ZHANG, XIUQIANG - HENAN KEY LABORATORY OF BIOMASS ENERGY; LI, MEI-CHUN - LSU AGCENTER; DONG, JU - LSU AGCENTER; LEE, SUNYOUNG - KOREAN FOREST RESEARCH INSTITUTIE; CHENG, HUAI; LEI, TINGZHOU - HENAN KEY LABORATORY OF BIOMASS ENERGY; WU, QINGLIN - LSU AGCENTER

Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2019
Publication Date: 3/20/2019
Citation: Zhang, J., Zhang, X., Li, M.-C., Dong, J., Lee, S., Cheng, H.N., Lei, T., Wu, Q. 2019. Cellulose nanocrystal driven microphase separated nanocomposites: Enhanced mechanical performance and nanostructured morphology. International Journal of Biological Macromolecules. 130:685-694. https://doi.org/10.1016/j.ijbiomac.2019.02.159.
DOI: https://doi.org/10.1016/j.ijbiomac.2019.02.159

Interpretive Summary: Polymer composite materials are major products of commerce. A composite typically contains two or more constituent materials with different properties that, when combined, produce a product with characteristics that are more desirable than those of the individual components. One of the current approaches to composite fabrication is to use agro-based fillers (like saw dust, wheat straw, and nanocellulose) in a polymeric matrix, but the results have been variable. A key parameter is the adhesion between the filler and the matrix; thus, if there is no adhesion between the cellulose filler and the polymer matrix, the resulting polymer/cellulose composite has mediocre properties. In this work, the nanocellulose filler was grafted with an acrylic polymer. The modified filler can now be loaded onto an acrylic polymer matrix with noticeably improved mechanical properties. This methodology should be useful to composite manufacturers in two ways: 1) for a manufacturer looking to improve the mechanical properties of a composite, this approach offers a feasible method to do so; 2) the results provide an improved fundamental understanding of the adhesion mechanism between the filler and the polymer matrix.

Technical Abstract: The interest of modification of cellulose nanocrystals (CNCs) lies in its potential to homogenously disperse CNCs in hydrophobic polymer matrices and to promote interfacial adhesion. The acrylate polymers, poly(butyl acrylate) (PBA) and poly(methyl methacrylate) (PMMA) chains, were grafted from the surface of CNCs, imparting their hydrophobic trait. The successful grafting modification led to an increased thermal stability of modified CNCs (MCNCs), and hydrophobic surface modification was integrated with crystalline structure and morphology of CNCs. The nanocomposites with 7 wt% MCNCs/PBA-co-PMMA indicated an increase in Young’s modulus of more than 25-fold and in tensile strength at about 3 times compared to that of neat PBA-co-PMMA copolymer. In addition, the storage modulus and glass transition temperature of MCNCs/PBA-co-PMMA nanocomposites were also largely improved compared to these of neat PBA-co-PMMA copolymer. A microphase separated morphology of MCNCs/PBA-co-PMMA nanocomposites was observed. Therefore, the hydrophobically modified MCNCs were effective reinforcing agents for the PBA-co-PMMA thermoplastic elastomers.