Rheological Characteristics of Starch-Based Biodegradable Blends

Area of Science:

• Polymer Science
• Materials Science
• Biomaterials

Background:

• Thermoplastic starch (TPS) offers biodegradability but has limitations in performance and processability.
• Blending TPS with synthetic biodegradable polyesters like poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) can overcome these challenges.

Purpose of the Study:

• To investigate the morphology, thermal properties, and rheological behavior of TPS/PBAT and TPS/PBAT/PLA blends.
• To assess the impact of blending on the performance and processability of thermoplastic starch.

Main Methods:

• Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) for morphology and elemental analysis.
• Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for thermal properties.
• Rotational rheometry (steady shear and dynamic oscillation tests) to evaluate rheological behavior.

Main Results:

• SEM and EDS confirmed the morphology and composition of the blends.
• TGA and DSC provided insights into the thermal stability and transitions of the materials.
• All samples displayed shear thinning behavior, well-described by the Carreau model.
• TPS remained solid, while TPS/PBAT and TPS/PBAT/PLA blends showed viscoelastic liquid behavior above their melting temperatures, with frequency-dependent storage and loss moduli.

Conclusions:

• Blending thermoplastic starch with PBAT and PLA significantly improves its performance and processability.
• The resulting polymer blends exhibit tunable viscoelastic properties suitable for various applications.
• These findings contribute to the development of advanced biodegradable materials.