Thermoplasts

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Question

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BPSC AE Paper 6 (Mechanical) 14 Oct 2022 Official Paper

have a three-dimensional network of primary bonds as polymerization proceeds in all directions
are long chain molecules held together by secondary bonds
have decreasing ability to deform plastically with increasing temperature
have secondary bonds and as the thermal energy increases, the secondary bonds never break

Answer 1

Explanation:

Thermoplasts:

Polymers that soften when heated and stiffen when cooled, with both processes being completely reversible are known as a thermoplastic polymers.
Thermoplastic polymers can be recycled.
Thermoplastic polymers consist of long linear molecular chains held together by weak secondary bonds or by inter-winding.
In thermoplastic polymers, cross-linking is absent between the molecular chains.
Examples of thermoplastic polymers are Acrylics, PVC, Nylons, etc.
The thermoplastics are synthesized by addition polymerization.
The melting point and tensile strength of thermoplastic are low.

Thus, option (2) is the correct answer.

Additional Information Thermosetting polymer:

Plastics that are ‘set’ under the application of heat and/or pressure is known as a thermosetting polymer.
The thermosetting polymers can not be recycled.
The thermosetting polymers consist of three-dimensional structures having strong covenant bonds to make rigid solid.
The thermosetting polymers are synthesized by condensation polymerization.
When compared with thermoplastic, thermosetting has high modulus, rigidity, and dimensional stability.
Examples of thermosetting polymers are Epoxies, Amino resins, etc.