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MANUFACTURING OF PLASTIC COMPONENTS
1 What are the characteristic of thermoplastics ?
ANS: Themoplastics polymers soften when heated and harden, when cooled.These types of polymers are soft and ductile. They have low melting temperature and can be repeatedly moulded and remoulded to the required shapes.
2 List out the material for processing of plastics?
ANS: The following metioned are the various polymer additives used in practice:
(1) Filler material (2) Plasticizers (3)Stabilizers
(4) colorants (5)Flame retardants (6) Reinforcements (7)Lubricants.
3 List the advantage of cold forming of plastics?
• Cold forming can be carried out at room temperature
• It is used to produce filament and fibres
• It is a simple process.
4 What is film blowing?
Ans: In this process a heated doughy paste of plastic compound is passed through a series of hot rollers, where it is squeezed into the from of thin sheet of uniform thickness. It is used for making plastic sheets and films.
5 What are the types of plastics ?
Ans: Polymers are classified in two major categoies:
o Thermoplastic polymers (Soften when heated and harden when cooled) o Thermosetting polymers (Soften when heated and permanently hardened when cooled).
6 What is compression moulding?
Ans: The main objective is to melt the material due to compression.
7 Name the parts made by rotational moulding.
Ans: Rotational moulding process is mostly used for the production of toys in P.V.C like horse, boats, etc. Larger containers upto 20 m3 capacity, fuel tanks of automobile are made from polythene and nylon. This process is also used for production of large drums, boat hulls, buckets, housings and carrying cases.
8 What is parison ?
Ans: Blow moulding consists of extrusion of the heated tubular plastic piece called as parison which is transferred to the two piece mold.
9 Define degree of polyenerization.
Ans: It is the number of repetitive units present inone molecule of a polymer.
Degree of polymerisation =Molecular weight of a polymer / Molecular weight of a single monomer
10 What is rotational mouldig of plastics?
• Rotataional moulding also called as roto-moulding.
• A measured amount of polyemer power is placed in a thin walled metal mould and the mould is closed.
• Then the mould is rotated about two mutually perpendicular axes as it is heated.
11.What are the two types of polymerization.
12. Rubber is a ___________________ Polymer
Rubber is a Organic Polymer.
13.Write the two types of Injection Moulding.
1.Ram Or plunger type injection moulding 2.Screw type Injection Moulding
Polymers are long chain molecules and are formed by polymerization process,linking and cross linking a particular building block called monomer, a unit cell.
Plastic is defined as the organic polymer which can be moulded into any required shape with the help of heat and pressure.
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