Crosslinked biopolymers: Experimental evidence for scalar percolation theory

Rheological measurements have been performed on pectin biopolymers close to the sol-gel transition. From these measurements scaling exponents were determined independently for the viscosity, s=0.82(5), for the elastic modulus, t=1.93(8), for the frequency-dependent modulus, Δ=0.71(2), and for the relaxation times below and above the transition, νz=2.67(12) and νz’=2.65(9). The exponents satisfy the scaling relations predicted by the theory and their numerical values agree with those from scalar elasticity percolation. Universal scaling functions were constructed from the data for the complex modulus and the dynamic viscosity.