Recycled Cellulose Polypropylene Composite Feedstocks for Material Extrusion Additive Manufacturing

Area of Science:

• Materials Science
• Polymer Science
• Additive Manufacturing

Background:

• Consumer-grade packaging plastics offer potential for additive manufacturing but often exhibit poor mechanical properties and dimensional instability.
• Reinforcing these recycled plastics with additives can enhance part stiffness and reduce warpage/shrinkage.

Purpose of the Study:

• To investigate the reinforcement of recycled polypropylene using cellulose waste materials.
• To develop a green composite feedstock for extrusion-based additive manufacturing.
• To evaluate the impact of cellulose fillers on the properties of 3D-printed recycled polypropylene.

Main Methods:

• Recycled polypropylene composites were fabricated with waste paper, cardboard, and wood flour using solid-state shear pulverization.
• Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) were used to assess filler content.
• Dynamic mechanical analysis (DMA) and tensile testing were performed to evaluate mechanical properties.

Main Results:

• Thermogravimetric analysis confirmed higher filler incorporation in recycled polymer composites compared to virgin polymer composites.
• Dynamic mechanical analysis revealed a 20-30% increase in storage modulus upon addition of cellulose materials.
• While tensile strength did not significantly increase at 10 wt% cellulose, the elastic modulus of virgin polypropylene increased by 38%.

Conclusions:

• Cellulose waste materials can be effectively incorporated into recycled polypropylene to create composite feedstock for additive manufacturing.
• The addition of cellulose enhances the stiffness and elastic modulus of the printed parts.
• Interfacial weakness between the filler and the polymer matrix was identified as a limiting factor for tensile strength improvement.