Surface modification of phosphogypsum and application in polyolefin composites

Area of Science:

• Materials Science
• Polymer Science
• Waste Management

Background:

• Phosphogypsum (PG) is a major industrial waste product with significant environmental concerns.
• Developing effective methods for utilizing PG is crucial for sustainable waste management.
• Incorporating PG into polymer matrices offers a potential route for its valorization.

Purpose of the Study:

• To investigate the performance of phosphogypsum (PG) as a filler in polypropylene (PP) and high-density polyethylene (HDPE) matrices.
• To evaluate the effects of calcination and surface modification on PG properties.
• To assess the mechanical properties and morphology of PG-filled polymer composites.

Main Methods:

• Calcination of PG at 500°C to transform its crystalline structure (CaSO₄·2H₂O to CaSO₄).
• Surface modification of PG using three different modifiers, evaluated by FTIR, oil absorption, water floatability, and contact angle.
• Fabrication of PP and HDPE composites with varying weight fractions of modified PG.
• Characterization of mechanical properties (tensile strength, impact strength) and morphology (SEM) of the composites.

Main Results:

• Calcined PG (CaSO₄) showed improved whiteness and impurity fixation.
• Modified PG dispersed uniformly in PP and HDPE matrices at low filling content.
• HDPE matrix showed increased tensile strength with PG addition, while PP showed a decrease.
• Impact strength of HDPE decreased with PG, while PP's impact strength increased initially then decreased.
• PG-filled composites exhibited lower apparent density, indicating lightweight characteristics.
• HDPE filled with PG showed better mechanical properties compared to those filled with calcium carbonate (CC).

Conclusions:

• Calcination and modification are effective in preparing PG for polymer composite applications.
• PG can be successfully incorporated into PP and HDPE matrices, offering lightweight properties.
• The mechanical performance of PG-filled composites is matrix-dependent, with HDPE showing promising results.
• PG utilization in polymer composites presents a viable strategy for waste valorization and sustainable material development.