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Full text release has been delayed at the author's request until September 01, 2028

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Fabrication and Blending of Nanostructured Microfibrous Chitin Material With Poly(Lactic Acid) for Enhancement of Thermomechanical Properties

Lindenberger, Amy L.
http://orcid.org/0000-0002-9619-0157
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1683828635899468

Abstract Details

2023, Doctor of Philosophy (PhD), Ohio University, Chemical Engineering (Engineering and Technology).
Nanofibers and nanocomposites are one method used to enhance the properties of existing polymers. Commercially produced, practical grade chitin from shrimp shells was processed using pulsed ultrasonication and then incorporated into the PLA matrix using a two-roll mill as composites. Composites of 1, 3, and 5 wt% chitin in PLA were analyzed by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and isoconversional kinetic analysis. Tensile and izod impact tests were done on injection molded test specimens for the same range of composites. Pure PLA samples were prepared in the same manner. Field emission electron microscopy (FESEM) of the chitin and PLA-ultrasonicated chitin composites showed that the nanostructured microfibrous chitin material incorporated into the composites retained much of its natural structure. In general, the thermal properties of the composites were similar to those of pure PLA. The melting point measured for the composites with DSC for the range of 0-5 wt% chitin-loading demonstrated a melting point decrease of 5°C, from 151.1 to 146.5°C. The glass transition temperature decreased from 52.6 to 47.3°C. The cold crystallization temperature decreased by 10°C from 109.9 to 99.9°C over the same range of chitin loading. The effective activation energy measured by isoconversional kinetic analysis using the Ozawa-Flynn-Wall model indicated a single step reaction consistent with the random bond scission process for all of the PLA and composite samples. The analysis was performed in air using TGA. Activation energies of 170 ± 11, 234 ± 12, 251 ± 11 kJ/mol were measured for 1, 3, and 5 wt% chitin in PLA, respectively. The value for PLA was 191 ± 9 kJ/mol consistent with published values. The increase in activation energy from 1 wt% to 5 wt% chitin loading is almost 50%. This is a dramatic increase in thermal stability, possibly due to the protection of PLA by a surface coating of chitin. The mechanical properties related to tensile strength generally stayed constant or decreased. The Young’s modulus, however, increased from 3021 to 3385 MPa, a factor of 12%. This increase is the result of the reinforcement of the PLA by chitin. This dissertation research showed improvement in some of the thermomechanical properties of the PLA-ultrasonicated chitin composites enabling their use in more applications. The composites also demonstrated an increase in Young’s modulus and exhibited some improvements to toughness at lower chitin content despite small decreases in yield strength and ultimate tensile strength. The size distribution of chitin particles in the composites was quantified using the Index of Dispersion and the Global Shannon Entropy. Both of these measures indicated that the particles were well dispersed.
Marc Singer (Advisor)
Rebecca Barlag (Committee Member)
Jason Trembly (Committee Member)
Martin Kordesch (Committee Member)
John Staser (Committee Member)
Monica Burdick (Committee Member)
160 p.
Chemical Engineering; Plastics
composites; chitin; poly(lactic acid); ultrasonication; roll mill

Recommended Citations

Citations

  • Lindenberger, A. L. (2023). Fabrication and Blending of Nanostructured Microfibrous Chitin Material With Poly(Lactic Acid) for Enhancement of Thermomechanical Properties [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1683828635899468

    APA Style (7th edition)

  • Lindenberger, Amy. Fabrication and Blending of Nanostructured Microfibrous Chitin Material With Poly(Lactic Acid) for Enhancement of Thermomechanical Properties. 2023. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1683828635899468.

    MLA Style (8th edition)

  • Lindenberger, Amy. "Fabrication and Blending of Nanostructured Microfibrous Chitin Material With Poly(Lactic Acid) for Enhancement of Thermomechanical Properties." Doctoral dissertation, Ohio University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1683828635899468

    Chicago Manual of Style (17th edition)

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© 2023, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.
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