Injection-molded thermoplastic cassava starch modified with single and mixed polyol plasticizers

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Growing demand for sustainable, biodegradable materials drives research into alternatives like thermoplastic starch (TPS).
• Plasticizers are crucial for processing TPS, significantly impacting its mechanical properties and thermal behavior.
• Understanding polyol plasticizer effects is key to optimizing TPS for various applications.

Purpose of the Study:

• To investigate the impact of single and mixed polyol plasticizers (glycerol, xylitol, sorbitol) on the performance of injection-molded TPS.
• To analyze how polyol molecular weight influences TPS properties, including thermomechanical processability and final product characteristics.
• To identify optimal plasticizer combinations for balancing processability and performance in TPS.

Main Methods:

• Cassava starch was modified with single and mixed polyol plasticizers via extrusion.
• Thermoplastic starch extrudates were processed into test specimens using injection molding.
• Comprehensive characterization included melt flow index, moisture content, water contact angle, tensile, dynamic mechanical thermal analysis, FTIR, XRD, SEM, and TGA.

Main Results:

• Higher molecular weight polyols (xylitol, sorbitol) showed lower plasticizing efficiency but stronger hydrogen bonding with starch.
• Increasing polyol molecular weight enhanced tensile strength, Young's modulus, decomposition temperature, and glass transition temperature.
• Moisture content and surface stickiness decreased significantly with higher molecular weight polyols, though processability and melt viscosity were negatively affected.

Conclusions:

• A co-plasticizer blend of glycerol and xylitol is recommended for injection-molded TPS, balancing processability and performance.
• Optimized TPS exhibits improved mechanical strength, thermal stability, and reduced moisture absorption.
• The developed TPS holds potential for rigid, biodegradable products like pet chew toys, cutlery, and plant pots.