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]]>Powder Mixing – Powder mixing is an operation that serves to make two or more components uniformly distributed in the powder bed.
Mechanisms – There are three main mechanisms involved in the mixing process, related to the different kinds of particle motion.
Problems during powder mixing – Powder segregation (demixing) is the opposite process of mixing, which means the separation of the drug from the powder components. Under some circumstances, the mixing process provides the necessary situations for powder to segregate, because, during the mixing process, particles are moving relatively close to each other, and their movement may differ due to their different properties, such as size, shape, or density. Conversely, particles having similar properties tend to move together, causing that region of the powder bed to have a higher composition concentration. Some other handling processes may also cause powder segregation, such as transportation, packing, feeding, and storage. The smallest region that can measure the homogenous state in a powder mixture is called the scale of scrutiny and can be a length, area, or volume. The scale of scrutiny is a scale of the finished product. For instance, for a 100 mg tablet, the scale of scrutiny is 100 mg. When the scale of scrutiny is large or the particle size is small, which indicates a large number of particles are present in the sample, the powder mixture are relatively uniform. Segregation can never be completely avoided, so powder sampling is preferred for the final product.
Mixing equipment –
Multiple choice questions:
1.An operation that serves to make two or more components uniformly distributed in the powder bed is called as
a)powder segregation
b)powder mixing
c)powder size reduction
d)comminution
2.How many mechanisms are involved in the mixing process of powders?
a)1
b)2
c)3
d)5
3.Which of the following mechanisms are involved in the mixing process?
a)Convection
b)Shear
c)Diffusion
d)All of these
4.In which of the following the large group of particles are moving together in the mixer, driven by the rotational force provide by a mixer vessel, paddle, blade, ribbon, or gas flow?
a)Convection
b)Shear
c)Diffusion
d)All of these
5.The mixing rate is relatively high in which of the following mechanisms?
a)Convection
b)Shear
c)Diffusion
d)All of these
6.The action that one layer of powder particles moves relative to another layer of particles is known as
a)Convection
b)Shear
c)Diffusion
d)All of these
7.Shear mixing can be caused by particles from a different powder layer, having different velocities developed in a rotary vessel or due to the compression force and extension of the powder bed.
a)true
b)false
8.The rate of shear mixing is intermediate and mainly causes _____ mixing.
a)microscopic
b)semi microscopic
c)macroscopic
d)all of these
9.The moment of individual particles, due to random motion of powder particles is called
a)Convection
b)Shear
c)Diffusion
d)All of these
10.Powder segregation is also known as
a) demixing
b)mixing
c)sticking
d)flocculation
11.Which of the following handling processes may cause powder segregation?
a)transportation
b)packing
c)feeding
d)all of these
12.The smallest region that can measure the homogenous state in a powder mixture is called
a)the scale of scrutiny
b)the scale of homogenosity
c)the graph of scrutiny
d)the scale of mixing
13.Which of the following mixing equipment’s are used in powder mixing?
a)mortar and pestle
b)ribbon mixer
c)nautamixer
d)all of these
14.The mortar and pestle method combines _____ and _____ in a single operation.
a)comminution and mixing
b)comminution and demixing
c)separation and mixing
d)sampling and mixing
15.Fluidization of the powder particles can be achieved by blowing cooled and filtered air into the equipment.
a)true
b)false
Solutions:
References:
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The post Powders: Powder handling, manufacturing and equipments, special care and problems in manufacturing of powders and MCQs for GPAT, NIPER, Pharmacist and Drug Inspector Exam appeared first on Gpatindia: Pharmacy Jobs, Admissions, Scholarships, Conference,Grants, Exam Alerts.
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