Question

The process of cross-linking in polymerization affects the mechanical properties of the resulting polymer by:

• A. Decreasing its tensile strength
• B. Making it more flexible
• C. Increasing its thermal stability
• D. Reducing its electrical conductivity

Hint:

Cross-linking locks polymer chains together — this boosts heat resistance but limits flexibility!

Answer 1

The Correct Option is C

Cross-linking is the formation of covalent bonds between different polymer chains, resulting in a three-dimensional network structure. This process significantly influences the mechanical and thermal properties of polymers.
When polymers are cross-linked, their molecular motion is restricted. This leads to an increase in thermal stability, as more energy is required to break the interconnected structure. Cross-linked polymers are also more resistant to deformation under heat and pressure, which is why they are commonly used in high-temperature and high-stress applications.
Clarification of incorrect options:

• (A) Cross-linking generally increases tensile strength rather than decreasing it.
• (B) It actually reduces flexibility, making the material more rigid.
• (D) Electrical conductivity is typically unrelated unless the polymer is doped with conductive fillers.

Hence, the primary mechanical effect of cross-linking is increased thermal stability of the polymer.