Definition
A grinding disperser is a type of laboratory equipment used to crush, disperse, and homogenize solid particles in a liquid medium. It depolymerizes the agglomerated particles and distributes them evenly in the dispersion medium through mechanical force, forming a stable suspension system to meet the requirements of sample uniformity and fineness for subsequent testing or processing.
How it works:
The equipment usually works on the principle of high-speed shearing and grinding. The motor drives the rotor to rotate at high speed in the stator cavity, generating strong mechanical shear and turbulence. The sample is squeezed, collided and rubbed in the narrow gap between the rotor and the stator, and the particle aggregates are gradually broken. At the same time, the vortices formed by the liquid medium promote the uniform dispersion of particles. Some models combine the impact of grinding beads to further improve the crushing efficiency of hard materials. The entire process follows the physical relationship between energy input and particle size reduction, and the energy expenditure model for particle breakage can be described using the following formula: E = k (1/df - 1/diwhere E is the specific energy input, k is the material-related constant, diand dfThe initial and final particle diameters are respectively.
Measurement and evaluation methods
The evaluation of the grinding dispersion effect is usually based on the particle size distribution and stability of the dispersion system. Laser diffraction is a common method for determining the size distribution of particles, and the volume distribution data is obtained by analyzing the scattering pattern of particles to the laser. Dynamic light scattering technology is suitable for particle size analysis of nanoscale dispersions. Dispersion stability can be evaluated by standing observation of stratification time, centrifugal settlement experiments, or zeta potential measurements. Changes in viscosity can also indirectly reflect the dispersion state and are measured at a constant shear rate using a rotary viscometer. It is recommended to take multiple samples and measurements after the operation to ensure data representativeness.
Influencing factors
The grinding dispersion effect is affected by multiple factors. Equipment parameters include rotor line speed, rotor and stator clearance design, processing time and cycle mode. The process conditions involved the viscosity of the dispersion medium, the ratio of solid content, the initial particle size of the sample and the hardness of the material. Chemical factors such as the type and amount of dispersant can change the surface properties of the particles and promote wetting and electrostatic repulsion. Temperature control is critical, and long-term high-speed operation can lead to heat-sensitive sample denaturation or solvent volatilization. The sequence of operations such as the pre-mixing step and the dosing method will also affect the final dispersion quality.
Applications:
The equipment is widely used in industrial and scientific research fields that require fine decentralization. In the coatings and inks industry, it is used for the dispersion of pigments and fillers to ensure uniform color and stability. In the preparation of nanomaterials, it is used for the deagglomeration and dispersion of carbon nanotubes, graphene, etc. in the matrix. Battery slurry preparation relies on the homogeneous mixing of active materials, conductive agents, and binders. It is used in the food industry for the homogenization of sauces and chocolate pulp. The environmental detection field is used for the pretreatment of soil and sediment samples to fully release the target components. The cosmetics industry is used to prepare lotions and pastes. These applications require equipment that can provide controlled shear strength and good repeatability.
Selection reference
The selection should comprehensively consider the sample characteristics and process objectives. For high-hardness or fibrous materials, models with high torque and wear-resistant structures should be selected, and cooling systems should be considered. When dealing with systems with high viscosity, it is necessary to pay attention to the motor power and shaft seal design. Nanoscale dispersion requires the device to produce sufficient shear rates and may require special rotor construction. If the sample is heat-sensitive or volatile, choose a model with temperature control or vacuum function. In terms of safety, attention should be paid to the chemical compatibility of explosion-proof requirements and contact materials. Ease of routine maintenance, noise levels and compliance with relevant safety standards should also be taken into account. It is recommended to verify the suitability of the equipment through small-batch process tests.