The Poisson's ratio (μ) of natural rubber undergoing strain-induced crystallization was studied across a broad stretch range. Below the crystallization onset stretch (\({\lambda }_{{||}}\)* ≈ 4.1), μ remains near 0.5, indicating incompressibility. Beyond \({\lambda }_{{||}}\)*, μ decreases with increasing crystallinity, reaching 0.33 at fracture (\({\lambda }_{{||}}\) ≈ 7.1), as the matrix transforms from amorphous to semicrystalline. The true stress at fracture, accounting for lateral contraction, is approximately 85% of the estimated value assuming μ = 0.5. These insights are vital for modeling the mechanical behavior of strain-crystallizing elastomers.
- Takuho Naraoka
- Ruito Tanaka
- Kenji Urayama
