Session: Research Posters

Paper Number: 172858

Compressive Response and Material Characterization of Chitin Biocomposite Foam: Structure-Properties Relationship 

Abstract

Polymeric foams are commonly used in various industries due to their energy absorption, cushioning, and good insulation properties.  Foams can be manufactured with various densities depending on functional needs.  While the manufacturing of foams can be modified based on needs to make the most advantageous structure, the process leads to significant ecological challenges.  Sustainability of foams is a primary concern in recent times, as many of the polymeric foams are not biodegradable and spend several decades, even centuries, in landfills and in nature.

Recently, a more natural, sustainable foam, Chitin foam, has been introduced in some industries as an alternative material to traditional foams.  With any new material, characterizing a material is essential for understanding its mechanical, chemical, structural, and thermal properties.  Understanding materials’ properties aids in determining what applications are better suited for the material.  In this work, Chitin foam is characterized by conducting compression tests, spectroscopy techniques, differential scanning calorimetry (DSC), and Fourier Transform Infrared spectroscopy (FTIR).

Microscopic techniques are used to examine the internal structure of foams.  In this work, scanning electron microscopy (SEM) and an optical profilometer were used to determine cell morphology attributes such as edge connectivity, cell wall thickness, and cell diameter.  From the micrographs, it is determined that the Chitin foam material is a closed-cell foam, the average cell wall thickness is 0.119 mm, and the average cell diameter is 2.563 mm.  Understanding these attributes aids in understanding the behavior of the Chitin foam under different loading conditions.

Compression tests, at different strain rates for different aspect ratios, were conducted on Chitin foam samples.  Three regions can be identified on the compressive stress-strain curve: (1) Liner elastic region where cell walls bend but recoverable when unloaded, (2) Plateau region where the cell walls begin to collapse at a roughly constant rate and (3) Densification region where the cell walls are crushing together and material compresses which causes the stress to increase rapidly.  For a strain rate of 0.1 s^-1, the compression test results show that as the aspect ratio increases, the plateau stress increases.  It is also seen that densification starts at a higher strain value as the aspect ratio increases.  There was no general trend observed for the strain rate of 0.76 s^-1.

When comparing aspect ratios of 0.5, 0.86, and 2, the compression test results show that as the strain rate increases, the plateau stress increases.  At an aspect ratio of 0.5, the onset of densification starts at nearly the same strain, but the onset of densification starts sooner with increased strain rate at aspect ratios of 0.86 and 2. 

Comparing the plateau region of all samples, it is seen that for a given aspect ratio, the slope of the plateau region increases as the strain rate increases.  The area under the compressive stress-strain curve is the energy absorbed per unit volume by the material.  The results show that the energy absorbed by Chitin foam increases for a given aspect ratio.

Although Chitin is a more sustainable, natural and ecologically friendly alternative to traditional foams, its properties must prove to be the same or better that its counterparts.  The remaining work includes thermal properties testing, analysis of the FTIR spectra and an investigation of structure-property relationship correlation to performance attributes.

Presenting Author: April Bonner University of Memphis

Presenting Author Biography: 4th-year Ph.D. student at the University of Memphis in the Mechanical Engineering department. 9 years in industry as a Senior Packaging Engineer.

Authors:

April Bonner University of Memphis
Amir Hadadzadeh University of Memphis