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(a) (i) Describe, with the aid of diagrams, the addition polymerisation process - Leaving Cert Engineering - Question 6 - 2011
Question 6
(a) (i) Describe, with the aid of diagrams, the addition polymerisation process. (ii) Name one polymer material produced by addition polymerisation. (b) With refer... show full transcript
Worked Solution & Example Answer:(a) (i) Describe, with the aid of diagrams, the addition polymerisation process - Leaving Cert Engineering - Question 6 - 2011
Step 1
Describe, with the aid of diagrams, the addition polymerisation process.
Answer
Addition polymerisation is a chemical process that involves the joining of small molecules known as monomers to form a long-chain polymer. This reaction typically occurs with unsaturated monomers that contain double bonds (C=C).
Step 1: Initiation
In the first step, a free radical is generated which initiates the reaction. This free radical can be produced by various methods, such as heat or radiation.
Step 2: Propagation
The generated free radical reacts with a monomer, opening its double bond and forming a new radical. This new radical then continues to react with more monomers, resulting in the continuous growth of the polymer chain.
Step 3: Termination
Eventually, two growing polymer radicals can combine or react with an impurity to terminate the chain growth, resulting in the final polymer structure.
Step 2
Step 3
Name the process and describe the principle of operation;
Answer
The process illustrated in the diagram is known as Extrusion. In this method, thermoplastic powder or granules are fed into a heated chamber. The rotating screw within the chamber moves the material while simultaneously applying pressure to force it through a die. This continuous process ensures that the material is evenly melted and shaped as it exits the die, producing a continuous profile of the desired shape.
Step 4
Step 5
Step 6
Explain the function of any three of the following polymer additives: Plasticiser, Filler, Lubricant.
Answer
Plasticiser
Plasticisers are added to polymers to enhance their flexibility. They work by reducing the intermolecular forces between polymer chains, allowing them to move more freely.
Filler
Fillers are additives that improve the mechanical properties of the polymer, such as its strength and durability. They reduce production costs by replacing some of the expensive polymer material while maintaining overall product quality.
Lubricant
Lubricants are used to facilitate easier processing of polymers. They help in reducing friction during the molding process, improving flow characteristics and preventing wear on equipment.