Nonlinear and linear viscoelastic behaviors of thermoplastic vulcanizates containing rubber nanoparticle agglomerates

Dependence of the nonlinear and linear viscoelastic behaviors of thermoplastic vulcanizates (TPV) on the content (φ) of rubber nanoparticle agglomerates (NPAs) was explored by dynamic oscillation shear tests. Under a large strain, TPV exhibit a φ-dependent yield stress (σ_y) as σ_y∝φ^1.53±0.87. As φ increases, the rubber NPAs network becomes stronger, and the elastic modulus and viscosity of TPV increase. φ-dependent modulus (G₀ ^') of TPV is G₀ ^'∝φ^3.18±0.24 in the low-ω region. Rubber NPs agglomerate to form a network more easily than rigid particles. The fractal dimension d_f (=1.65 ± 0.09) of the rubber NPAs in TPV is lower than the universal d_f (~1.8) of rigid particles aggregates. The φ-dependent modulus G₀ ^' of TPV in the linear viscoelastic region shows G₀ ^'~{(φ_c−φ)¹,forisolatedrubberNPAs,φ≤φ_c(φ−φ_c)^2.15±0.12,forrubberNPAsnetwork,φ≥φ_c, where φ_c is the percolation threshold of φ. This study provides an understanding of the viscoelasticity of TPV containing rubber NPAs and their network structure.