CONTINUOUS DEVULCANIZATION BY SHEAR FLOW STAGE REACTION CONTROL TECHNOLOGY FOR RUBBER RECYCLING, PART 3

STUDY OF DEVULCANIZATION PROCESS FOR EPDM

Abstract

We studied devulcanization process by measuring rubber state, viscosity, gel fraction, its effective network chain density and average molecular weight of sol. When passing through grinding zone, vulcanized rubber was ground by screw rotation and its size became small. Next, devulcanization proceeded in the devulcanizing zone and viscosity of rubber decreased. Gel fraction and its effective network chain, density decreased too. Finally, gel fraction of devulcanized rubber was 45% and its effective network chain density was one twentieth of virgin vulcanized rubber. On the other hand, average molecular weight of sol part did not change and its value was nearly equal to virgin raw rubber. Devulcanization process depended on shear stress by screw rotation. Gel fraction and its effective network chain density decreased by increasing screw rotation. Devulcanization rate depended on reaction temperature and became high by raising temperature.