Question

1. How does a thermoplastic material differ from a thermosetting material ? Give one example
Plastic toys, PVC shoes.
C LONG-ANSWER TYPE QUESTIONS : Answer in 20-25 words
thermoplastic and thermosetting materials.
2. Mention two advantages and two disadvantages of synthetic fibres.
3. Mention a few problems associated with the excessive use of plastics.
4. Explain why the following are made of thermosetting plastics.
(a) Pressure cooker handle
(b) Electric plugs/switches
DASAN​

Answer 1

Answer:

Ans 1) Thermoplastics vs. Thermosetting Polymers: Properties, Processing and Applications

Thermoplastics and thermosetting polymers are types of plastic that undergo different production processes and yield a variety of properties depending on the constituent materials and production method. The terms thermoplastic and thermoset stand for how a material is or can be processed under a changed temperature.

Ans 2) Advantages of Waterways:

1. It is the cheapest means of transport.

2. It is a fuel-efficient and eco-friendly mode of transport.

Disadvantages of Waterways:

1. It depends of weather conditions.

Ans 3) Few problems associated with the excessive use of synthetic plastic are as follows:-

1) As plastic don't burn completely, it pollutes the environment.

2) Animals such as cows, dogs etc die when they eat the non-biodegradable  plastic.

3) When they are burnt, they produce gases which are harmful for the environment.

4) They clog drains leaving overflowing drains during a rain.

5) They could be used for some extent. If damaged, it could be no more of a good use.

Ans 4) the handles of a saucepan are made of thermosetting plastic because it is a bad conductor of heat and does not get heated up while cooking. (b) Electric plugs/ switches/ plug boards are saucepan is made of thermosetting plastic because it is a bad conductor of electricity.

Answer 2

Answer:

Q1.

A. Thermoplastics

• It can be melted and recycled.
• Dimensional with no crosslinks.
• Prepared mostly by additional polymerisation.
• Mostly processed by conventional methods such as injection molding, extrusion and blow molding.
• Examples include polyethylene (PE), polyethylene terphthalate (PET).

B. Thermosetting plastics

• It cannot be melted and recycled.
• Dimensional with multiple crosslinks.
• Prepared mostly by condensation polymerisation.
• Mostly processed by special methods such as compression, transfer and casting.
• Examples include Phenol formaldehyde, melamine formaldehyde.

Q.2

Advantages....

1- They do not shrink.

2- They are quick drying and need very little or no ironing.

Disadvantages...

1- Synthetic fibres do not absorb water or sweat. In hot and humid weather therefore the clothes made of synthetic fibre stick to the body and make the wearer uncomfortable.

2- Synthetic fibres melt and burn easily.

Q.3

1)As plastic don't burn completely, it pollutes the environment.

2) Animals such as cows, dogs etc die when they eat the non-biodegradable plastic.

3) When they are burnt, they produce gases which are harmful for the environment.

4) They clog drains leaving overflowing drains during a rain.

Explanation:

Q.4

a) Pressure cooker handle need to resist sustained heat transferred to it while cooking for a long time. So, it uses thermosetting plastics as it cannot be melted.

b) Electric plugs/switches are made from thermosetting plastics because they are bad conductors of heat and electricity. It does not allow the current to pass through it.O