Developing Post-Consumer Recycled Flexible Polypropylene and Fumed Silica-Based Nanocomposites with Improved...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Mechanical recycling of post-consumer flexible polypropylene (PP) is challenging due to its lightweight nature and degradation during reprocessing.
• Recycling alters PP's thermal and rheological properties, limiting its applications.

Purpose of the Study:

• To investigate the impact of two fumed nanosilica (NS) types on improving the processability of post-consumer recycled flexible polypropylene (PCPP).
• To evaluate the effect of NS on the thermal stability and rheological properties of PCPP.

Main Methods:

• Fourier-transform infrared spectroscopy (ATR-FTIR)
• Thermogravimetric analysis (TGA)
• Differential scanning calorimetry (DSC)
• Melt flow index (MFI) testing
• Rheological analysis

Main Results:

• Nanosilica addition significantly enhanced the thermal stability of PCPP, increasing onset decomposition temperature by approximately 15 °C.
• Nanosilica acted as a nucleating agent, increasing polymer crystallinity without altering transition temperatures.
• Processability improved, evidenced by increased viscosity and moduli in nanocomposites compared to control PCPP.
• Hydrophilic NS showed the greatest improvement in viscosity recovery and MFI reduction due to hydrogen bonding interactions.

Conclusions:

• Fumed nanosilica effectively enhances the thermal stability and processability of post-consumer recycled polypropylene.
• Nanosilica acts as a reinforcing agent and nucleating agent, counteracting degradation from recycling.
• The choice of nanosilica surface treatment (hydrophilic vs. organically modified) influences the extent of property recovery.