Compared with linear polymers, branched-chain polymers typically show which difference in solid-state packing and related properties?

Introduction / Context:
Polymer architecture (linear vs branched) influences crystallinity, density, and thermal properties. Branching generally hinders close packing and reduces crystallinity.

Given Data / Assumptions:

• Linear chains pack more efficiently than highly branched chains.
• Greater packing efficiency often raises density, crystallinity, and melting point.
• Branched chains introduce irregularity and free volume.

Concept / Approach:
Branch points disrupt lamellar crystal formation, lowering crystallinity and density and often decreasing tensile strength and melting temperature compared with linear analogues of similar chemistry and molecular weight.

Step-by-Step Solution:
Relate branching to packing inefficiency.Infer reduced crystallinity/density and melting point.Select “higher irregularity in atomic packing.”

Verification / Alternative check:
Contrast LDPE (branched) with HDPE (linear): LDPE has lower density and melting point due to branching.

Why Other Options Are Wrong:
Higher density/strength/melting point: more typical of linear, well-packed chains.Perfect lamellae: contradicted by branching defects.

Common Pitfalls:
Ignoring molecular weight effects; comparisons should assume similar Mw.

Final Answer:
Higher degree of irregularity in atomic packing