Doctoral Dissertations


"In offering a scientifically succinct methodology which leads to property-enhanced biodegradable polymer products for broader application, as well as in promoting the use of bio-sourced renewable polymers such as Polylactide (PLA) in biodegradable polymers with desirable properties from petroleum based polymers such as PBAT, this study and its results both directly and indirectly contribute to the technological solutions that address growing environmental and energy problems caused by the increased use of and reliance upon nondegradable, nonrenewable, petroleum-based plastics. This work studied blends of PBAT and PLA compounded with organoclay through direct melt mixing in a twin-screw extruder and a batch mixer, determined the most compatible organoclay for this blend, evaluated the role of the particles on the physical properties and morphologies of the blends, compared different mixing procedures, and evaluated the effect of clay loading on the properties. Blended properly with PLA, PBAT showed significantly enhanced modulus, which was further increased by addition of organoclay. Cloisite 30B was the organoclay focused on for this blend and the incorporation of this organoclay was found to improve the thermomechanical performance of the composites. In blends with equal weight contents of PBAT and PLA, organoclay platelets exhibited better dispersion when they were mixed with either of the two polymers first, than being premixed with the blend. Migration of particles from one phase to the others was observed in both sequentially mixed blends. In addition, the effect of an AC electric field, based on the rheological and thermal analysis, resulted in a significant increase on the dispersion of the clay platelets in the PLA "--Abstract, page iv.


Lee, Sunggyu
Ludlow, Douglas K.

Committee Member(s)

Xing, Yangchuan
Westenberg, David J.
Dogan, Fatih


Chemical and Biochemical Engineering

Degree Name

Ph. D. in Chemical Engineering


Missouri University of Science and Technology

Publication Date


Journal article titles appearing in thesis/dissertation

  • Effects of mixing sequence on the morphological and rheological properties of polymer-clay nanocomposites of poly(butylene adipate-co-terephthalate) and poly(lactic acid) blend.
  • Comparative effects of Cloisite 30B and Cloisite 15A on PBAT and PBAT/PLA blends.
  • Effect of organically modified clay loading on the rheological and mechanical properties of the PBAT and PLA blends.
  • Effect of high-voltage AC electrical field on the dispersion of organoclay in a Polylactide matrix.
  • Mechanical and morphological properties of poly(butylene adipate-co-terephthalate) and poly(lactic acid) blended with organically modified silicate layers.


xii, 104 pages

Note about bibliography

Includes bibliographical references (pages 98-103).


© 2011 Mahin Shahlari, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Biodegradable plastics
Plastic containers -- Environmental aspects
Clay minerals
Nanocomposites (Materials) -- Mechanical properties
Polymers -- Analysis

Thesis Number

T 10175

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Electronic OCLC #