Molecule weight distribution

Useful Technique for Cellulose Industry

RISE analyzes molecular weight distribution of many components within the cellulose industry such as pulp, carboxymethyl cellulose, polyacrylate, starch, biocides, lignin, black liquor, and hemicellulose.

Pulp: RISE can perform characterizations of pulp, including analyzing its chemical composition, fibre structure, density, and other physical properties. This is important for understanding the quality and properties of the pulp and how it can affect the printing process.

Carboxymethyl cellulose: This is a water-soluble polymer often used as an additive in printing inks and pulp to enhance their rheological properties and manage water retention. RISE can characterize carboxymethyl cellulose by analyzing its chemical composition, molecular weight, viscosity, and other relevant parameters.

Polyacrylate: Polyacrylate is a type of synthetic polymer used in various applications, including printing inks and water treatment. RISE can perform characterizations of polyacrylate to assess its properties such as molecular weight, solubility, reactivity, and stability.

Starch: Starch is a natural polymer often used as a binder in pulp and as an additive in printing inks to improve adhesion and manage water retention. RISE can perform characterizations of starch to assess its chemical composition, structure, and functional properties.

Biocides: Biocides are chemicals used to prevent the growth of microorganisms such as mold and bacteria in water-based systems. RISE can perform characterizations of biocides to assess their effectiveness, stability, and potential environmental impact.

Lignin: Lignin is a complex polymer naturally found in wood and other plant materials. It is often used as a raw material to produce chemicals and materials, including pulp and binders in printing inks. RISE can characterize lignin to assess its chemical composition, structure, and usability in various applications.

Black liquor: Black liquor is an alkaline solution used in the pulp industry to extract lignin from wood and other raw materials. RISE can perform characterizations of black liquor to assess its concentration, pH value, alkalinity, and other relevant parameters.

Hemicellulose: Hemicellulose is a polysaccharide found in plant cell walls and plays an important role in the structure and properties of pulp. RISE can characterize hemicellulose to assess its chemical composition, structure, and functional properties.

RISE has the capability to perform detailed analyses of molecular weight distribution in various types of cellulose samples, including bleached pulps, viscose solutions, and viscose fibres. For this purpose, an integrated high-temperature system for GPC analysis (Gel Permeation Chromatography) is used, equipped with a RI detector (Refractive Index Detector).

The molecular weight distribution of cellulose in different sample types can be analyzed by dissolving the samples and then running them through the GPC system at a constant temperature of 70°C. During the analysis, the cellulose molecules are separated and characterized based on their size and weight, allowing for a precise assessment of the distribution of different molecular weight fractions.

Methods and Instruments

Molecular weight distribution is a key parameter for understanding the structure and properties of polymer materials. Through careful analysis of molecular weight distribution, researchers and engineers can improve material design, optimize manufacturing processes, and ensure high quality and performance in a variety of applications.

Structural Characterization: Molecular weight distribution provides a detailed picture of the size variation among polymer molecules within a sample. This is crucial for understanding the chemical structure of the material and how it can affect its properties and behavior. For instance, a broad molecular weight distribution may indicate the presence of different polymer fractions with varying chain lengths, which can have significant implications for the mechanical, thermal, or optical properties of the material.

Quality Control: Molecular weight distribution can be used as a tool for quality control of polymer materials. By analyzing the distribution, one can assess the purity, homogeneity, and any potential contaminants in the material. This is particularly important in industrial applications where small variations in molecular weight distribution can impact the performance and durability of the product.

Process Optimization: For manufacturing and processing polymer materials, it is often necessary to optimize process parameters to achieve desired properties of the final material. Molecular weight distribution can be used as an indicator of how different process parameters affect the structure and properties of the material. By analyzing changes in molecular weight distribution, one can optimize the manufacturing process to maximize product quality and minimize costs.

Functionality: Molecular weight distribution can also affect the functionality and performance of the material in various applications. For example, a narrower molecular weight distribution can provide more homogeneous materials with uniform properties, which is important for applications where precision and uniformity are crucial, such as in the pharmaceutical industry or electronics manufacturing.

In summary, molecular weight distribution is a key parameter for understanding the structure and properties of polymer materials. Through careful analysis of molecular weight distribution, researchers and engineers can enhance material design, optimize manufacturing processes, and ensure high quality and performance in various applications. The method is well-suited for monitoring changes in operation or equipment of one or more process steps. It provides a measure of how the pulp quality has been affected by a process change. A reference before the process change is recommended to observe the difference in molecular weight distribution before and after.

For example, a shift towards a lower average molecular length indicates that the strength properties have deteriorated. By dissolving viscose fibers before analysis, we can similarly assess whether the fiber strength has been affected as a result of changes in molecular weight distribution. This can be supplemented, if necessary, with viscosity and light scattering detectors.

It is advisable to send multiple samples due to the time-consuming setup process.

Delivery

RISE offers a report that includes data in Excel format and relevant images and diagrams. It is carefully compiled using standard methods for the conducted analyses. The report also includes an assessment of measurement uncertainty to ensure the reliability of the presented results. All relevant parameters significant to the specific analysis are included to provide a comprehensive picture of the situation. Additionally, detailed comments and explanations are provided to offer further insight and understanding of the presented data.