Preparation and characterization of biodegradable copolyester-starch based foams

Area of Science:

• Materials Science
• Polymer Science
• Food Science

Background:

• Biodegradable polymers and starches are explored for sustainable packaging.
• Extrusion processing is a common method for creating starch-based foams.
• Optimizing foam properties requires understanding the interplay of material composition and processing parameters.

Purpose of the Study:

• To investigate the effects of regular and waxy corn starches blended with Eastar Bio Copolyester (EBC) on loose-fill foam properties.
• To determine how EBC content and starch moisture levels impact foam expansion, density, water solubility, and mechanical characteristics.
• To compare the performance of regular versus waxy corn starch in extruded foam applications.

Main Methods:

• Twin-screw extrusion of corn starch and EBC blends at various ratios.
• Inclusion of two corn starch types (regular and waxy), three EBC levels, and three moisture contents.
• Evaluation of foam properties including radial expansion, unit and bulk densities, water solubility index (WSI), compressibility, and spring index.

Main Results:

• Waxy starch foams showed greater radial expansion and lower densities compared to regular starch foams.
• Higher EBC content led to reduced expansion and increased densities; 10% EBC resulted in higher compressibility.
• Optimal expansion was observed at 19% and 22% moisture content, with 22% moisture yielding softer foams and a lower WSI (18.5%).

Conclusions:

• Waxy corn starch is more suitable for producing highly expanded, low-density foams.
• EBC content and moisture significantly influence foam morphology and properties, offering avenues for tailored material design.
• The study provides insights into optimizing starch-based foam formulations for specific applications, balancing expansion, density, and mechanical performance.