A New Approach to Estimating the Parameters of Structural Formations in HDPE Reactor Powder

Area of Science:

• Polymer Science
• Materials Science
• Crystallography

Background:

• Reactor powder (RP) morphology is crucial for polymer properties.
• High-density polyethylene (HDPE) synthesis involves complex crystallization processes.
• Understanding HDPE RP structure informs material design and application.

Purpose of the Study:

• To investigate the morphology of virgin HDPE reactor powder (RP).
• To correlate powder morphology with crystallization conditions.
• To analyze the structural features of shish-kebab formations.

Main Methods:

• Differential Scanning Calorimetry (DSC) for crystallinity and lamellar thickness.
• Scanning Electron Microscopy (SEM) for morphological units.
• Small-Angle X-ray Scattering (SAXS) for periodic structures.
• Wide-Angle X-ray Scattering (WAXS) for crystal structure.

Main Results:

• Identified macro- and micro-shish-kebab structures and individual lamellae.
• Revealed periodic morphoses (20-60 nm long periods) using SAXS, correlating with SEM observations.
• Estimated lamellar thickness and calculated surface energy based on DSC data and Gibbs-Thompson theory.
• Discussed fold regularity on shish-kebab lamellae and quantified morphosis percentages.

Conclusions:

• HDPE RP morphology is characterized by shish-kebab structures and lamellae.
• The observed morphology is attributed to specific crystallization conditions in suspension synthesis.
• Quasi-stationary synthesis regimes with overheating and shear stress variations likely influence HDPE RP structure.