مطالعه خواص ريولوژيكي آميزه هاي لاستيك - دوده در مرحله درهم فرورفتن مواد در مخلوطكنهاي داخلي

Study of Rheological Properties of Rubber / Carbon Black Compounds During Incorporation Stage in Internal Mixers

The rheological properties of the first stage (i.e., incorporation step) of mixing of rubber and carbon black in internal mixers are studied. The SBR and N330 were selected as the raw rubber and filler, respectively. Rheological measurements were carried out by the use of a modern rubber process analyzer instrument known as RPA 2000. A new method was developed based on experimental simulation of the mixing process in rheometer for the viscosity and modulus of rubber compound during incorporation step. A series of rubber/carbon black mixtures with different agglomerate sizes were first prepared in a laboratory internal mixer at various mixing times. Then an empirical relation was proposed to predict the effective filler volume fraction (EFVF) from mixing time, initial filler volume fraction, size of agglomerates and applied frequency in rheometer. A sharp increase in viscosity of a mixture during the incorporation stage is observed which is due to the immobilization of entrapped rubber in filler agglomerates and increasing the filler content known as EFVF. A similar trend but in opposite direction was previously reported for the second stage of mixing and dispersion. The results of this research and those reported for the second stage of mixing are in close agreement.