Polymerisation of polyfunctional monomers (functionality > 2) tends to produce networks. Which general property outcome is most associated with such crosslinked polymers?
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AGood mechanical strength
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BLow viscosity in the solid state
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CVery low melting point and easy remelting
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DNone of these
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EUnlimited cold flow at room temperature
Answer
Correct Answer: Good mechanical strength
Explanation
Introduction / Context:Monomer functionality dictates polymer architecture. When functionality exceeds two, networks form at gelation, resulting in thermoset behaviour and enhanced structural properties.
Given Data / Assumptions:
- Crosslinking restricts chain mobility.
- Mechanical strength and heat resistance increase with network density (to a point).
- Melting is not observed for fully cured networks.
Concept / Approach:Crosslinked polymers cannot flow like viscous melts; their rigidity and cohesive strength generally rise. Therefore, “good mechanical strength” is the characteristic outcome, whereas low viscosity/melting are inconsistent with networks.
Step-by-Step Solution:Recognise effect of functionality on network formation.Relate crosslinks to strength and dimensional stability.Select “Good mechanical strength.”
Verification / Alternative check:Phenolic and epoxy composites demonstrate high strength due to crosslinked matrices.
Why Other Options Are Wrong:Low viscosity/low melting: contradict network behaviour.None of these/unlimited cold flow: incorrect; networks resist flow.
Common Pitfalls:Assuming more crosslinks always increase toughness; excessive crosslinking can embrittle despite high strength.
Final Answer:Good mechanical strength