Particle Size
1. Definition
● Particle Size refers to the dimensions of individual silica gel particles. For irregularly shaped particles, the "equivalent diameter" is typically used to describe their size. It is one of the most fundamental and critical physical properties of powders and granular materials.
2. Particle size directly affects several key product properties:
Specific Surface Area : Smaller particles have a larger specific surface area, leading to higher adsorption capacity and chemical reactivity.
Bulk Density and Porosity : The particle size distribution determines how particles pack together, influencing the product's density and fluid permeability.
Flowability: Uniform particles exhibit better flowability, which is critical for automated production and packaging.
End-Product Performance: In applications such as coatings and toothpaste, particle size directly affects the product's texture, gloss, cleaning efficacy, etc.
3. Units of Measurement
● Direct Dimension: Millimeter (mm), Micrometer (μm), Nanometer (nm).
● Mesh: A common standard referring to the number of openings per linear inch in a sieve. A higher mesh number indicates finer particles.
4. Key Concepts: Particle Size Distribution and Qualification Rate
● Particle Size Distribution (PSD): Refers to the relative percentage of particles of different sizes within a sample. It is typically represented as a range or a distribution curve and is a key indicator of product uniformity.
● Particle Size Qualification Rate: The weight percentage (%) of particles that fall within the specified size range (upper and lower limits) relative to the total sample weight. This is a core parameter for quality control. A higher qualification rate indicates more uniform particle size.
Testing Methods
● Sieve Analysis: Uses a stack of standard test sieves. It is low-cost but time-consuming, with limited accuracy for fine particles.
● Laser Diffraction Analysis: Measures particle size distribution by analyzing the scattering pattern of a laser beam passed through the sample. It is fast, accurate, reproducible, and the mainstream method in modern laboratories.
Summary
● Particle Size is a core parameter for measuring silica gel particles. Its distribution and qualification rate collectively determine the product's consistency, performance, and quality stability. Precise control of particle size allows for meeting the specific requirements of various downstream applications.
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