Nanocavitation in Carbon Black Filled Styrene鈥揃utadiene Rubber under Tension Detected by Real Time Small Angle X-ray Scattering

详细信息    查看全文

• 作者：Huan Zhang ; Arthur K. Scholz ; Jordan de Crevoisier ; Fabien Vion-Loisel ; Gilles Besnard ; Alexander Hexemer ; Hugh R. Brown ; Edward J. Kramer ; Costantino Creton
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：February 14, 2012
• 年：2012
• 卷：45
• 期：3
• 页码：1529-1543
• 全文大小：681K
• 年卷期：v.45,no.3(February 14, 2012)
• ISSN：1520-5835

文摘

Nanocavitation was detected for the first time in carbon black filled styrene鈥揵utadiene rubber (CB-SBR) under uniaxial loading by real time small-angle X-ray scattering (SAXS) using synchrotron X-ray radiation. A three phase model was developed to calculate the void volume fraction from the scattering invariant Q determined from the observed SAXS patterns. The normalized scattering invariant Q/Q₀, where Q₀ is the invariant before deformation, greatly increased above a critical extension ratio 位_onset which we attribute to the formation of nanovoids. Analysis of the 2D scattering patterns show that voids formed are 20鈥?0 nm in size and elongated along the tensile direction. Cavities formed beyond 位_onset are smaller as 位 increases. Results from the scattering experiments are strongly supported by macroscopic volume change measurements on the samples under similar uniaxial strain. A nearly constant nanocavitation stress 蟽_onset (25 MPa) was observed when the filler volume fraction _CB was larger than 14%. This value is much higher than that predicted based on the elastic instability of small voids in an unfilled elastomer and shows only a weak dependence on the cross-linking density 谓_C in heavily cross-linked samples. An energy based cavitation criterion stressing the importance of confined domains between particles or clusters of particles was adopted and found to be consistent with the observed results. The nanocavities are thought to alter the local stress state and promote local shear motion of filler particles.