| 초록 |
The effect of the cure time of rubber compound on the adhesion with brass-plated steel cord was investigated in conjunction with the formation, growth and degradation of the adhesion interphase formed between the rubber compound and brass-plated steel cord and the formation of weak boundary layer in rubber near adhesion interphse. With increasing the cure time from a fourth of t90 to four times of t90, the pull-out force after vulcanization increased significantly up to a half of t90, and then increased slightly to t90, and decreased slowly further increase of cure time. This decrease in pull-out force at prolonged vulcanization may be explained by the severe degradation of rubber compound attached to the adhesion interphase. Also, at a prolonged vulcanization, the adhesion interphase with a rich ZnS layer, which may act as a barrier to copper diffusion for the formation of the adhesion interphase of copper sulfide. After thermal aging of the adhesion samples, the pull-out force decreased in comparison with that of the unaged. The decrease of pull-out force after thermal aging stemmed mainly from the decline of tensile property after thermal aging. The adhesion property after humidity aging was different from that after thermal aging. With increasing the cure time to a half of t90, the pull-out force increased. But a further increase in the cure time caused a decline in pull-out force. This phenomenon can be explained by the degradation of the adhesion interphase. At longer cure time, a severe growth of copper sulfide and a large generation of dezincification were observed in the adhesion interphase. At shorter cure time, a significant growth of copper sulfide in the adhesion interphase does not appear whereas the formation of ZnS layer appeared after humidity aging. With increasing cure time, the formation weak boundary layer in rubber near adhesion interphase increased resulting in the cohesive failure of rubber layer. The properformation of the adhesion interphase and the good physical property of the rubber compound at optimum cure time can be ascribed to the high retention of adhesion property. |
