Typical molecular-weight range of commercial plastics: which range is most representative?

Introduction / Context:
Engineering thermoplastics achieve useful mechanical properties only when the number-average or weight-average molecular weight is sufficiently high to entangle chains and distribute loads. Understanding order-of-magnitude ranges is vital in polymer processing and property prediction.

Given Data / Assumptions:

• Commodity plastics often exhibit Mn or Mw from roughly 2e4 up to 1e6 depending on polymer and grade.
• Very low molecular weights behave like waxes or oligomers.
• Extremely high values (10^9+) are unrealistic for linear chains due to processing limits.

Concept / Approach:
A representative lower bound for practical plastics is around 2e4, where tensile strength and melt elasticity become useful. While many grades exceed 2.5e4, the option closest to a reasonable, representative range among the choices given is 20,000 to 25,000.

Step-by-Step Solution:
Eliminate impossible or nonsensical ranges (5,000 to 1,000; 10^9 to 10^11).Recognise 1,000 to 5,000 as too low for most plastics (oligomeric).Choose 20,000 to 25,000 as the most representative option provided.

Verification / Alternative check:
Datasheets often quote Mw: LDPE 1e5–5e5; PP 1e5–7e5; PVC 6e4–1.2e5. The selected option captures a plausible minimum threshold.

Why Other Options Are Wrong:
Too low or physically unrealistic for processable plastics.

Common Pitfalls:
Confusing degree of polymerisation with molecular weight; not distinguishing Mn vs Mw.

Final Answer:
20,000 to 25,000