염소화 처리에 따른 천연고무 쉬트(sheet)의 마찰특성을 새로운 형태의 마찰시험기를 이용하여 조사하였다. 아울러 염소화에 따른 표면의 분자구조, 표면 모폴로지 및 경도의 변화를 조사하였다. 천연고무 쉬트의 표면은 염소화 반응으로 분자구조의 변화가 확인되었고, 장시간 처리조건에서는 고리화 반응도 관찰되었다. 염소화 처리시간에 따라 마찰계수는 큰 폭으로 감소하였고, 염소화 초기단계에서 보다 급격한 감소를 보였다. 염소화에 따른 마찰계수 감소의 주요 원인은 경도와 표면 거칠기로 설명되었다. 경도의 증가는 접촉면적과 고무의 변형을 감소시킴으로써 각각 접착마찰과 히스테리시스 마찰을 감소시키고, 거칠기의 증가는 접촉면적을 감소시켜 접착마찰을 감소시킨 것으로 설명되었다.
Using a new friction tester, the frictional property of chlorinated-natural rubber sheet was investigated as a function of the chlorination time. The changes in molecular structure, morphology, and hardness on the surface of the rubber sheet were also investigated with the chlorination time. It was confirmed that the molecular structure on the surface of natural rubber sheet has changed due to the chlorination reaction, and with a longer chlorination treatments a cyclization reaction was observed. The frictional coefficient decreased significantly with increasing the chlorination time, and the decrease rate was the highest at the initial stage of the chlorination reaction. Such rapid drop in the frictional coefficient--upon chlorination--can explained by two main parameters: surface roughness and hardness. The increase in the hardness caused a reduction in both the contact area and deformation of rubber, thereby decreasing the adhesive and hysteresis frictions. The increase in the surface roughness reduced the contact area, which in turn decreased the adhesive friction.