Solid State Cross-Linked Polypropylene via Reactive Extrusion: A Scalable Approach

Area of Science:

• Polymer Science
• Materials Science
• Chemical Engineering

Background:

• Conventional melt processing of semicrystalline polymers can lead to degradation.
• Solid-state reactive extrusion offers an alternative processing route.
• Modifying polymer properties requires controlled chemical reactions.

Purpose of the Study:

• To investigate solid-state reactive extrusion for modifying isotactic polypropylene.
• To evaluate the impact of benzoyl peroxide on polymer structure and properties.
• To compare solid-state modification with conventional melt-state processing.

Main Methods:

• Solid-state reactive extrusion of isotactic polypropylene with benzoyl peroxide below the melting temperature.
• Fourier-transform infrared spectroscopy (FTIR) and 13C CP-MAS NMR for structural analysis.
• Differential scanning calorimetry (DSC) for thermal properties and rheological measurements for network formation.

Main Results:

• Polypropylene backbone integrity was preserved during solid-state processing.
• Increased crystallization temperatures and reduced crystallinity were observed.
• Rheological data indicated increased molecular connectivity and network formation, with storage modulus increasing with peroxide concentration.

Conclusions:

• Solid-state reactive extrusion is an effective method for modifying polypropylene.
• This approach enhances intermolecular connectivity and network formation while minimizing degradation.
• It presents an energy-efficient and scalable strategy for tailoring polymer properties.