The Uses of a Vacuum Mixer
A vacuum mixer prevents air bubbles and thoroughly mixes all of the materials, making them more uniform. It is used for various applications including medical, manufacturing and chemical formulation analysis.
The VPM2 can create a variety of programs and store up to 99 mixes. If you need something simpler the VPM Mini is a good option.
Preparation of cements and amalgams
Cements and amalgams are the most common direct restorative materials used in daily dental practice. Various types are available, ranging from the traditional amalgam, with its long clinical history and good esthetics, to resin composites and glass-ionomer cements (GIC). [1]
In addition to their primary chemical combining ingredients, all dental cements contain an unstable powder component and a liquid component which is volatile in the presence of air. The main causes of porosities and other deteriorating properties in the resulting cured cements are air inclusion and entrapment in the structure as well as evaporation of excess monomer during exothermic polymerization thereby releasing bubbles.
Accordingly, the preparation of cements and amalgams requires their mixing in a substantially airless environment. To achieve this, a vacuum mixer can be used to evacuate the vapors and gaseous reaction products formed during mixing and subsequent polymerization.
The mixture of the powder component and the liquid component is placed in a mixing vessel within an evacuable housing with mixing vanes that are vacuum mixer operable from outside the housing. The housing is provided with vacuum conduits which can be connected to a vacuum source for withdrawing the vapors and the gaseous reaction product from the mixing vessel.
The evacuated space between the powder component particles is then flooded with the liquid component, and mechanical homogenization is achieved. The method of preparing the cement is illustrated in published International Patent Application WO 86/06618, by Tepic.
Mixing of powders and granules
When mixing powdered active ingredients with liquids it is important that the particles are wetted and dispersed uniformly. Efficient mixing minimizes costs for raw material and downstream filtering or rework operations. Vacuum mixers are an effective means for this. They accelerate the sublimation process of powdered active ingredients by providing a high shear force and avoiding any agglomeration. In addition, a vacuum can be applied, allowing the vapors to be extracted and the solvent vaporized in a dehumidification unit.
Vacuum can also be used to inject powders sub-surface in the batch, preventing them from becoming dusty or floating on the surface of the liquid. This can reduce the overall processing time and improve product quality. It is also an ideal method for drying heat-sensitive materials.
In addition, a vacuum can be used to reduce the temperature of the mixing process, reducing thermal degradation. This is particularly beneficial for food and pharmaceutical products. Vacuum mixing can also help improve the efficiency of the production process and reduce energy consumption.
Vacuum mixers are a good choice for mixing a wide range of powders and granules. They have a V-shaped chamber that is fitted inside a case, pumping out air to create vacuum conditions. The central mixer drum is equipped with a rotating blade insert that churns the materials. The combination of rotary action and high shear forces ensures that the powders are thoroughly mixed and dispersed.
Degassing
The vacuum mixer can be used to degass powdered or granulated materials in liquids. This is particularly important in the case of thixotropic products like powdered silica, which are often added to liquids such as epoxy resins or plastic epoxies during manufacturing. Using a vacuum mixer for this purpose can help to prevent air from entering these products and improve the quality of the finished product.
This process works by creating a low-pressure vacuum environment in which the mixing blades can thoroughly churn the mixture. This helps mixer manufacturer to remove any trapped air bubbles from the material and eliminates any oxidation or other unwanted chemical reactions during the mixing process. This process can be very useful in the manufacturing of pharmaceuticals, cosmetics, or other chemicals that must be kept as a gas-free and stable mixture.
Vacuum mixing also has other applications in the manufacturing of molded composites and a variety of other industries. It can be used to reduce oxidation and speed up the processing of heat-sensitive materials, and it is also beneficial for powdered fillers that need to be dispersed in liquids.
For the compounding of high-performance liquid epoxy coatings, it is essential to vacuum degass the resin components before adding the fillers. If the liquids are not vacuum degassed, the air bubbles will rise to the surface and break them, which could result in a cloudy appearance and reduced performance.
Impregnation of filler pellets
A vacuum mixer can be used to impregnate pellets with a thermoplastic polymer. The mixture is then injected into an injection molding process to form a reinforced article. The polymer preferably consists of a polypropylene homopolymer or copolymer with a small amount of other alpha-olefins. The mixture may also contain other fillers, such as alumina or silica. The pellets can have a sphere, plate, acicular or flake shape. A sphere-shaped pellet has a diameter of up to 10 mm, while a flint or whisker-shaped pellet has a diameter of 0.1 to 5 mm.
The ILE can be removed from the SCE pellets by soaking them in acetone. Alternatively, the ILE can be removed from the SCE using a liquid CO2 critical point dryer. This removes the ILE without requiring the use of solvents that can damage the pellets.
Vacuum mixing equipment is available in a variety of configurations for all types of applications. These include a range of single-shaft devices that can handle low viscosity formulations to multi-agitator systems for batching high viscosity, high density compounds. Many of these mixers are designed for vacuum and internal pressure operation and feature jacketed vessels that can be heated or cooled with steam, electric heating or a combination of both. They can be equipped with a wide variety of agitation systems, including counter-rotating anchor and blade, top or bottom entering high speed, high shear homogenizing turbine or dispersing agitators.