Polymer science — elastomers (rubber-like polymers) can typically be stretched up to approximately what multiple of their original dimensions and still recover substantially on unloading?

Introduction / Context:
Elastomers are polymers with high elasticity arising from their molecular architecture (long, flexible chains with occasional cross-links). Their defining feature is the ability to undergo large reversible deformations compared with plastics or metals. This question asks for a representative upper-bound multiple of extension often cited in introductory materials science texts.

Given Data / Assumptions:

• Room temperature deformation; strain rates typical of manual stretching.
• Lightly cross-linked elastomers (e.g., natural rubber, SBR) under safe service stress.
• “Extend up to” refers to order-of-magnitude capability, not continuous service strain.

Concept / Approach:

Elastomers can sustain very large strains (hundreds of percent). A commonly quoted figure is extension up to about 10 times the original length (≈900% strain) before rupture, depending on formulation and temperature. Recovery on unloading is substantial because chains uncoil/ recoil, with cross-links restoring the network configuration. Options like three or five times are achievable for many elastomers, but the traditional teaching point emphasizes the remarkable ability to reach about an order-of-magnitude extension under favorable conditions.

Step-by-Step Solution:

Verification / Alternative check:

Material datasheets for natural rubber and certain thermoplastic elastomers report elongation at break ranging from 400% to 1000%, supporting the “≈10×” statement for suitable compounds.

Why Other Options Are Wrong:

Three, five, or seven times — Possible for many grades but do not capture the commonly taught upper capability benchmark.

Common Pitfalls:

Confusing elastic recovery at service strain with elongation at break; ignoring variation across elastomer families and filler/cross-link density.

Final Answer:

ten times their original dimensions