2.4 Mooney viscosity, Payne effect and flocculation rate constant of unvulcanized compounds
Mooney viscosity (ML(1+4), 100 °C) was tested using a Mooney viscometer (MV 2000VS, Alpha Technologies) according to ASTM D1646. The Payne effect or filler–filler interaction of the uncured silica-filled compounds were studied by using a Rubber Process Analyzer (RPA 2000, Alpha Technologies) at 100 °C, frequency 0.5 Hz and varying strains in the range of 0.56–100%. The difference of storage moduli at low strain (i.e. 0.56%) and high strain (i.e. 100%) is reported.
The flocculation rate constant (ka) of the uncured silica-filled compounds was studied by using the RPA at 100 °C, strain 0.56%, frequency 1.00 Hz, and test time for 12 min. The ka was calculated following Eqs. (2) and (3)