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The formation of space charge in EPDM (ethylene-propylene-diene terpolymer) filled with ATH (alumina trihydrate) or clay has been investigated by measuring charge distributions. It is found that the type and amount of space charge developed in crosslinked EPDM or its compounds is governed by the type of diene in EPDM and the composition of the semicon electrodes. The amount of charge in the EPDM compounds containing 1,4-hexadiene decreases with an increase of ATH content and increases with an increase of clay content. The heat treatment of EPDM compounds in a vacuum oven increases the amount of space charge in them. These features were explained by the effects of low molecular weight molecules present at the surface of fillers. It is found that the homocharge increases as the clay content increases, while EVA decreases the homocharge in the EPDM compounds. Possible reasons for these results are discussed.

Due to the stronger bond strength of the Fe-S molecule than that of the Fe-Fe molecule, at the stage of nucleation the surface-segregated sulfur hinders the systematical movement of matrix atoms into the exact positions at the surface for the formation of the (110)[001]. When the (110) grains form selectively at the strip surface, even a subdivision of a low concentration of surface-segregated sulfur determines, therefore, the degree of disturbance against movement of matrix atoms and, thus, the direction of the (110): the (110)[001] at a much lower concentration of surface-segregated sulfur and the (110)[[uvw].sub.[not equal to][001]] under a lower condition of segregated sulfur. Due to the relatively higher mobility of matrix atoms, the probability that, at a fixed final reduction, the (110) grains survive through the selective growth of (100) grains and have finally a chance for selective growth decreases with increasing heating rate. Index Terms--3% silicon steel, nucleation, segregation kinetics, selective growth, sulfur.

Focuses on space charge distributions in ethylene-propylene-diene terpolymer (EPDM) compounds. Use of polymer/filler composites; Role of interface between the filler and the polymer; Details on experimental procedures; Results of the study.