Novel thermoplastic starch-clay nanocomposite foams
Meng Chen1, Biqiong Chen, Julian R G Evans
1Department of Materials, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
Nanotechnology
|September 7, 2010
Summary
Novel thermoplastic starch (TPS) foams incorporating clay were developed. Ammonium-treated clay acts as a blowing agent, creating regular foam structures with high porosity, unlike natural clay or TPS alone.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Thermoplastic starch (TPS) is a biodegradable polymer with potential applications, but it suffers from cracking during storage.
- Clay nanocomposites offer enhanced material properties but require effective dispersion of clay particles.
- Developing novel foam structures from biopolymers is crucial for sustainable materials.
Purpose of the Study:
- To prepare novel thermoplastic starch (TPS)-clay nanocomposite foams using melt-processing.
- To investigate the effect of urea as a plasticizer on TPS stability and clay dispersion.
- To explore the role of ammonium-treated clay in forming regular foam structures.
Main Methods:
- Melt-processing of thermoplastic starch (TPS) with natural and ammonium-treated clays.
- Use of urea as a plasticizer to prevent TPS cracking and improve clay dispersion.
- X-ray diffraction (XRD) to confirm nanocomposite formation by analyzing clay basal spacing.
- Scanning electron microscopy (SEM) to characterize foam structure and porosity.
- Thermogravimetric analysis (TGA) to investigate gas evolution during foaming.
Main Results:
- Urea effectively plasticized TPS, preventing cracking and enhancing ammonium-treated clay dispersion.
- XRD confirmed the formation of nanocomposites, indicated by increased basal spacing in both natural and treated clays.
- SEM revealed regular, spontaneously formed foam structures with 84% porosity in TPS-ammonium-treated clay nanocomposites.
- TPS and TPS-natural clay nanocomposites did not exhibit regular foam structures.
- TGA supported the hypothesis that ammonia gas, released from the ammonium surfactant, acts as an internal blowing agent.
Conclusions:
- Novel TPS-clay nanocomposite foams with regular structures and high porosity were successfully prepared.
- Ammonium-treated clay, through ammonia gas release, functions as an effective internal blowing agent for foam formation.
- Urea is a beneficial plasticizer for improving TPS processability and clay dispersion in nanocomposites.
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