Definition
An electric dispersion mixer is a type of laboratory equipment that uses a motor to drive the mixing components to shear, disperse, and mix liquid or solid-liquid mixtures at high speed. It is commonly used in sample preparation to achieve uniform dispersion, emulsification, or dissolution of materials, providing a uniform and stable sample system for subsequent analytical tests.
Principle
The core working principle of an electric dispersion mixer is based on the shear action in fluid mechanics. The motor drives the agitator head (such as the rotor-stator structure or blades) to rotate at high speed through the drive shaft, creating strong turbulence and high shear areas near the agitation head. When the material passes through this area, it is subjected to a combination of mechanical force and hydraulic force, and the agglomerated particles are broken and the different components are evenly mixed. The shear rate generated by it is closely related to the rotor line speed and structural design, which can be roughly described by the following relationship:
γ ≈ (π· D·N) / h
Among them γ represents the shear rate, D is the diameter of the rotor, N is the rotor speed, and h is the clearance distance between the rotor and the stator.
Main measurement methods
When using an electric dispersion mixer for sample processing, it is often necessary to evaluate its dispersion effect. Common measurement methods include particle size analysis (e.g., laser diffraction or dynamic light scattering to determine particle size distribution), viscosity measurement (using a rotational viscometer to monitor changes in the rheological properties of the system), and stability observation (determining the uniformity and persistence of dispersion systems by static layering or centrifugal stability testing). These measurements are performed under standardized operating conditions to ensure comparability and reproducibility of results.
Influencing factors
The dispersion mixing effect is affected by multiple factors. In terms of equipment parameters, the geometry of the mixing head, rotor speed, processing time and power input are the key variables. In the process conditions, the initial state, solid content, viscosity, temperature and surface properties of the material will also significantly affect the final dispersion quality. In addition, if the shape and size of the container do not match the mixing head, it may cause flow dead angles or insufficient vortex current, resulting in uneven dispersion. During operation, these factors should be comprehensively controlled according to the characteristics of the material.
Applications
Electric dispersion mixers are widely used in many industrial and scientific research fields. In the coatings and inks industry, it is used for the uniform dispersion of pigments in substrates; In food science, it can be used for the homogenization of sauces and emulsions; in the field of materials, assist in the preparation of nanomaterials and composite materials; It is often used for the pre-extraction treatment of soil, sediment and other samples in environmental testing. Different applications have specific requirements for dispersion strength, shear rate, and thermal control, and need to be adapted to the appropriate equipment configuration.
Selection considerations
Selecting the right electric dispersion mixer requires a system evaluation based on specific needs. The physical properties of the sample (e.g., viscosity, solids, sensitivity) and the target dispersion fineness should be defined first. Secondly, consider whether the speed range, torque output, and power stability of the equipment meet the process window. In terms of function, it is necessary to pay attention to whether it has speed regulation accuracy, overload protection, and easy to clean design. For temperature-sensitive samples, models with cooling jackets or temperature control modules are available. In addition, equipment safety, noise level and compatibility with existing workflows are also factors that need to be weighed in the actual selection.