msepostdoc-list Reminder for Mitch Rencheck's Preliminary Exam Seminar, Sept 26, at 8:30 a.m., in ARMS 1021 "Buckling Mechanics Metrology of Cellulose Nanocrystal Thin Films"

[Son, Rosemary E]

Please consider attending the following:

MATERIALS ENGINEERING
SEMINAR


"Buckling Mechanics Metrology of Cellulose Nanocrystal Thin Films"


By
Mitchell L. Rencheck
Purdue MSE Ph.D. Preliminary Exam

Advisor: Professor Chelsea S. Davis



ABSTRACT





A major current need for sustainability is in the area of polyolefin plastics (grocery bags, disposable water bottles, milk cartons, etc.) that continue to contaminate our oceans as consumption progresses. Within the cell walls of wood lies a structural component called cellulose which has the potential to be a solution due to the high mechanical properties of the material (σ = 7.5 GPa and E = 110-220 GPa). Cellulose on the nanoscale is referred to as crystalline nanocellulose (CNC) and can be processed into thin films to be used as a suitable, sustainable replacement. Before CNC films can be implemented, proper mechanical characterization must be conducted. A technique utilizing buckling instabilities is identified as a solution, but cannot scale up to thicker films and conventional techniques struggle to deal with difficult CNC film properties. Free standing buckling mechanics are examined to present a viable solution for CNC film mechanical characterization. A novel mechanical testing frame was built to measure the critical buckling load of thin films. A cellulose acetate based transparent film was tested to find a critical load of 0.033N which yields an elastic modulus of 19.31 GPa. An overestimation was observed from insufficient equipment calibration and must be corrected before geometrical changes can be attributed to the transparencies to determine frame accuracy and precision. Once calibrated, CNC films will be tested to determine elastic moduli and anisotropy by varying load direction, crystal orientation, and crystal aspect ratio.



Date: Tuesday, September 26, 2017

Time: 8:30 A.M.
Place: ARMS 1021




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