Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends

Area of Science:

• Polymer Science
• Materials Science
• Mechanical Engineering

Background:

• High-Density Polyethylene (HDPE) and Thermoplastic Starch (TPS) blends are widely used.
• Understanding their mechanical behavior is crucial for material design.
• Interfacial properties significantly influence blend performance.

Purpose of the Study:

• To investigate the mechanical behavior of HDPE/TPS blends.
• To evaluate the effect of HDPE-g-MA compatibilization on blend properties.
• To elucidate the toughening mechanisms in these polymer blends.

Main Methods:

• Preparation of HDPE/TPS blends with varying compositions.
• Addition of HDPE-g-MA as a compatibilizer.
• Mechanical testing, including fracture resistance and toughness evaluation (e.g., EWF method).
• Microstructural analysis to observe particle size and interfacial changes.

Main Results:

• Unmodified HDPE/TPS blends show high fracture resistance.
• Compatibilization with HDPE-g-MA significantly decreases fracture resistance.
• HDPE-g-MA addition reduces TPS particle size and increases surface area.
• A reaction between maleic anhydride and TPS hydroxyl groups likely decreases glycerol content, stiffening TPS particles.

Conclusions:

• Stiffer, smaller TPS particles reduce toughness and plastic deformation in HDPE/TPS blends.
• The primary toughening mechanism in these blends is shear-yielding.
• Reduced shear band formation due to stiff TPS particles lowers resistance to crack propagation.