Question

Each student needs to submit a pdf file in ONLY ONE of the following topics:

1. Modern mixing devices in the preparation of semisolids.

2. Segregation in solid dosage form manufacture.

3. Different models of rotor stator turbines.

4. Agitation patterns in solid feeders.

Answer 1

Solution:

Selected topic is modern mixing devices in the preparation of semisolids.

Modern mixing devices in the preparation of semisolids are stated as follows,

1. Planetary mixer : The principle of planetary mixers is very simple, which usually have two or three multi-hinged blades, when the paddles are revolution and rotation running at the same time, so that the material will flows up and down as well as around the inner cylinder,which can reach the mixing effect in a very short time.

Uses : The planetary mixer is particularly suitable for paste, high viscosity, high density materials dissolving, mixing, kneading and polymerization etc.

2. Sigma mixers : The sigma mixer is caused by a strong shearing action of a pair of mutually cooperating and rotating blades so that the semi-dry state or the rubbery viscous plastic material can react quickly to obtain a uniform mixing of the material. The sigma blade mixer machine is mainly composed of five parts: kneading part, base part, hydraulic system, transmission system and electric control system.

Uses : Sigma mixer is especially suitable for chewing gum, bubble gum, toothpaste, plastic, rubber, silicone rubber, dyestuff, pigment, ink, food base, architectural coating, carbon, cellulose, high viscosity Sealant, neutral glass glue, aluminum paste, silicone, pulp, cellulose, battery paste, dyes, silicone resin, cosmetics and other industries.

3. Shear mixers : A shear mixer disperses or transports, one phase or ingredients (liquid, solid, gas) into a main continuous phase (liquid), with which it would normally be immiscible. A rotor or impeller, together with a stationary component known as a stator, or an array of rotors and stators which is used either in a tank containing the solution to be mixed or in a pipe through which the solution passes, to create shear.

Uses : A high-shear mixer can be used to create emulsions, suspensions, lyosols (gas dispersed in liquid), and granular products. It is also used in the adhesives, chemical, cosmetic, food, pharmaceutical, and plastics industries for emulsification, homogenization, particle size reduction, and dispersion.