Preparation and characterization of nanocomposites, incorporating cellulose nanomaterials in polymer systems, 2020

Atlanta University and Clark Atlanta University Theses and Dissertations
Preparation and characterization of nanocomposites, incorporating cellulose nanomaterials in polymer systems, 2020
Brown, Sade
Contributor to Resource:
Mintz, Eric
Date of Original:
Degrees, Academic
Dissertations, Academic
United States, Georgia, Fulton County, Atlanta, 33.749, -84.38798
Cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) are of great interest as reinforcing agents for polymer matrix composites due to their nanoscale and specific intrinsic properties of high strength and stiffness, combined with low weight, biodegradability and the environmental benefits arising from its use. For many applications, it is highly desirable to improve the toughness and stiffness of these cellulose nanocomposites. In this study, two critical issues were addressed: good interfacial interactions at filler and matrix interface and improved dispersion of nanocellulose in polyolefins to achieve desired properties by various approaches. Addressing these critical issues is particularly crucial for the fabrication of nanocellulose composites due to the non-polar characteristics of thermoplastic polymers, which limits interaction between the nanocellulose and hydrophobic polymer systems. Nanocellulose/polyolefin composites were prepared by means of powder sintering, high-torque melt-mixing and in situ free radical polymerization. It was found that lignin-coated cellulose nanocrystals (L-CNC) and lignin-coated nanofibers (L-CNFs) can act as nucleating agents, promoting the crystallization rates of these polyolefins, and, the addition of nanocellulose enhances all other physical properties. However, there were no significant improvements in the thermal properties of the nanocellulose/polyolefin composites. The Young’s modulus, tensile strength, and storage modulus of the L-CNC/polyolefin nanocomposites were increased at a defined loading of L-CNCs due to the reinforcement effect of L- CNCs inside the polymer matrix. The incorporation of L-CNCs in maleic anhydride functionalized polymer systems resulted in improvement in the thermal and mechanical properties. The obtained mechanical results showed improvement in Young’s modulus, ultimate tensile strength, and tensile strength at a defined L-CNC loading for all nanocellulose/polyolefin composites. These improvements are due to better dispersion and compatibility of the L-CNCs in the hydrophobic polymer matrices, ultra-high molecular weight (UHMWPE), high-density polyethylene (HDPE) and polypropylene. We have found that the dispersion and distribution of CNCs in these polymer systems improved in the presence of lignin.
Date of award: 2020-05
Degree type: dissertation
Degree name: Doctor of Philosophy (PhD)
Granting institution: Clark Atlanta University
Department: Department of Chemistry
Advisor: Mintz, Eric
Metadata URL:
Holding Institution:
Clark Atlanta University
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