Poly (Lactic Acid)/Ground Tire Rubber Blends Using Peroxide Vulcanization

Area of Science:

• Materials Science
• Polymer Science
• Sustainable Materials

Background:

• Poly (Lactic Acid) (PLA) is a brittle bio-based polymer requiring property enhancement.
• Ground Tire Rubber (GTR) represents a significant waste stream from the automotive industry.
• Recycling GTR into polymer composites offers a sustainable solution for waste management.

Purpose of the Study:

• To develop a novel recycling pathway for automotive waste rubber.
• To improve the toughness and impact strength of Poly (Lactic Acid) (PLA).
• To investigate the effect of Ground Tire Rubber (GTR) particle size and grinding method on PLA properties.

Main Methods:

• Preparation of Poly (Lactic Acid) (PLA)/Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent.
• Two GTR grinding methods were employed: cryo-grinding and dry ambient grinding.
• Characterization of GTR particle size, composition, and blend properties including swelling, tensile strength, modulus, strain at break, energy at break, and impact strength.

Main Results:

• Grinding processes induced mechanical damage to rubber chains, with finer GTR particles containing more reinforcing fillers (carbon black, clay).
• PLA/GTR blends using the finest cryo-grinded GTR with DCP exhibited minimal tensile strength reduction (-30%) and maintained tensile modulus.
• Significant improvements were observed in strain at break (+80%), energy at break (+60%), and impact strength (+90%) compared to neat PLA.

Conclusions:

• The use of fine GTR particles, particularly from cryo-grinding, effectively enhances the ductility and impact resistance of PLA.
• Good dispersion of fine GTR and clay particles within the PLA matrix is crucial for property improvement.
• Crosslinking via DCP likely contributes to improved mechanical properties at the PLA/GTR interface and within GTR particles.