Accelerated Storage Induced Structural Evolution in Natural Rubber: A Comparative Study of Two Constant Viscosity...

Area of Science:

• Polymer Science
• Materials Science
• Rubber Technology

Background:

• Constant viscosity (CV) natural rubber is crucial for consistent processing.
• Understanding storage stability of different CV preparation methods is essential.
• Current mainstream methods include dry-mixing and latex-mixing.

Purpose of the Study:

• To compare the structural changes of CV natural rubber prepared by dry-mixing and latex-mixing methods under accelerated storage.
• To evaluate the impact of these preparation methods on mesostructure and microstructure.
• To assess the long-term stability of key physical and chemical properties.

Main Methods:

• Preparation of CV natural rubber using both dry-mixing and latex-mixing techniques.
• Accelerated storage testing for 48 hours.
• Analysis of mesostructure and microstructure variations.
• Measurement of Mooney viscosity (ML) and Wallace plasticity (P0).
• Assessment of molecular weight, molecular weight distribution, and molecular chain shape.

Main Results:

• Both methods maintained consistent macrogel content after storage.
• A slight increase in microgel (>1μ) content was observed with both methods.
• Molecular weight, distribution, and chain shape remained stable across both methods.
• Dry-mixing showed superior performance in maintaining Mooney viscosity and Wallace plasticity.
• Latex-mixing demonstrated an advantage in preserving the number of branches per chain.

Conclusions:

• Dry-mixing is superior for maintaining constant viscosity properties of natural rubber during storage.
• Latex-mixing excels at preserving the molecular branching structure of natural rubber.
• Both methods offer stability in key structural parameters like molecular weight and macrogel content.
• The choice of preparation method impacts specific performance characteristics during storage.