TY - JOUR
T1 - Porosity Governs Normal Stresses in Polymer Gels
AU - de Cagny, Henri C. G.
AU - Vos, Bart E.
AU - Vahabi, Mahsa
AU - Kurniawan, Nicholas A.
AU - Doi, Masao
AU - Koenderink, Gijsje H.
AU - Mac Kintosh, Fred
AU - Bonn, Daniel
PY - 2016/11/18
Y1 - 2016/11/18
N2 - When sheared, most elastic solids including metals, rubbers, and polymer gels dilate perpendicularly to the shear plane. This behavior, known as the Poynting effect, is characterized by a positive normal stress. Surprisingly, fibrous biopolymer gels exhibit a negative normal stress under shear. Here we show that this anomalous behavior originates from the open-network structure of biopolymer gels. Using fibrin networks with a controllable pore size as a model system, we show that the normal-stress response to an applied shear is positive at short times, but decreases to negative values with a characteristic time scale set by pore size. Using a two-fluid model, we develop a quantitative theory that unifies the opposite behaviors encountered in synthetic and biopolymer gels.
AB - When sheared, most elastic solids including metals, rubbers, and polymer gels dilate perpendicularly to the shear plane. This behavior, known as the Poynting effect, is characterized by a positive normal stress. Surprisingly, fibrous biopolymer gels exhibit a negative normal stress under shear. Here we show that this anomalous behavior originates from the open-network structure of biopolymer gels. Using fibrin networks with a controllable pore size as a model system, we show that the normal-stress response to an applied shear is positive at short times, but decreases to negative values with a characteristic time scale set by pore size. Using a two-fluid model, we develop a quantitative theory that unifies the opposite behaviors encountered in synthetic and biopolymer gels.
U2 - 10.1103/PhysRevLett.117.217802
DO - 10.1103/PhysRevLett.117.217802
M3 - Article
SN - 0031-9007
VL - 117
JO - Physical Review Letters
JF - Physical Review Letters
IS - 21
M1 - 217802
ER -