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Title: Study on the Evolution of Molecular Network Structure during Natural Rubber Processing

Abstract: The molecular network structure of natural rubber plays a crucial role in determining its mechanical properties and processing behavior. In this study, we investigated the evolution of molecular network structure during natural rubber processing using various analytical techniques including dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR), and small-angle X-ray scattering (SAXS). Our results showed that the molecular weight distribution and crosslink density increased significantly during vulcanization, leading to a more compact and stable network structure. Moreover, we found that the addition of certain additives such as sulfur accelerators could further enhance crosslinking efficiency and improve mechanical properties. These findings provide valuable insights into the fundamental mechanisms underlying natural rubber processing and may have important implications for optimizing industrial production processes.

Keywords: Natural rubber; Molecular network structure; Vulcanization; Crosslink density; Additives

Introduction:

Natural rubber is an important industrial material widely used in various applications ranging from automotive tires to medical devices due to its unique combination of elasticity, toughness, durability, and biocompatibility. The mechanical properties of natural rubber are largely determined by its molecular network structure which is formed through chemical crosslinking between polymer chains during vulcanization process.

The process of natural rubber vulcanization involves heating raw latex or solidified sheets with sulfur or other curing agents under pressure to form strong covalent bonds between adjacent polymer chains. This results in a three-dimensional interconnected network structure with varying degrees of cross-linking density depending on factors such as temperature, time duration, curing agent concentration etc.

In recent years there has been growing interest in understanding how different factors affect the evolution of molecular networks structures during natural rubber processing as it can help optimize production processes for better performance characteristics.

Methods:

In this study we used dynamic mechanical analysis (DMA) to measure changes in viscoelastic modulus over time at different temperatures ranging from room temperature to 150°C. Fourier transform infrared spectroscopy (FTIR) was used to analyze changes in chemical bonding patterns during vulcanization process. Small-angle X-ray scattering (SAXS) was used to investigate the morphology and size distribution of polymer aggregates.

Results:

Our results showed that the molecular weight distribution of natural rubber increased significantly during vulcanization, indicating that crosslinking density had also increased. This led to a more compact and stable network structure with improved mechanical properties such as higher tensile strength and elongation at break.

Moreover, we found that the addition of certain additives such as sulfur accelerators could further enhance crosslinking efficiency and improve mechanical properties by promoting faster reaction rates between polymer chains.

Conclusion:

In conclusion, our study provides valuable insights into how molecular network structures evolve during natural rubber processing under different conditions. Our findings suggest that optimizing curing agent concentration, temperature, time duration etc can lead to better performance characteristics for industrial applications. Further research is needed to explore other factors affecting molecular network evolution in natural rubber processing such as strain rate effects or aging behavior over time.