Higher degree of crystallinity equals

• A. Greater thermal conductivity
• B. Lower thermal conductivity
• C. No change
• D. Only affects optical clarity

Answer: (A)

Higher crystallinity means a more ordered, tightly packed structure that provides continuous pathways for heat to move. In polymers, heat is carried mainly by vibrations (phonons) and by chain interactions. Amorphous regions scatter these vibrations, hindering heat flow, while crystalline areas offer fewer scattering sites and denser packing, so heat can be conducted more efficiently. Therefore, increasing crystallinity raises thermal conductivity. The other options miss this transport effect: lower conductivity would be opposite, no change ignores the structural impact, and crystallinity affects more than just optical clarity.