Effects of Foaming Temperature and Carbon black Content on the Cure Behaviors and Foaming Characteristics of the Natural Rubber Foams

발포온도와 카본블랙 함량이 천연고무 발포체의 가황거동 및 발포특성에 미치는 영향

  • Published : 2006.09.30

Abstract

To investigate the influence of the foaming temperature and carbon black content on the cure behaviors and foaming characteristics of the foams. natural rubber (NR) was foamed at five temperature zones (145, 150, 155, 160 and $165^{\circ}C$) and different feeding ratios of the carbon black. A decreasing trend of the scorch time, $t_{s2}$ and cure time, $t_{90}$ was observed upon increasing foaming temperature and carbon black content. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be $165^{\circ}C$ where density of the loomed NRs is lower than those at other four temperature regions. The rule rate index of the NRs foamed at $145^{\circ}C$ is smaller than those at 150, 155, 160 and $165^{\circ}C$. The results of the expansion ratio and micrographs of the foamed NRs were founded to support the density characteristics. The thickness of each of the struts formed inside the rubber matrix decreases with increasing the foaming temperature, while it increases with increasing the carbon black content.

본 연구에서는 발포체의 가황거동과 발포특성에 발포온도 및 카본블랙 함량이 미치는 영향을 조사하기 위해 카본블랙을 변량 배합하고 $145^{\circ}C$에서 $165^{\circ}C$까지 $5^{\circ}C$ 간격으로 발포하여 천연고무 발포체를 제조하였다. 발포온도 및 카본블랙 함량이 증가함에 따라 $t_{s2}$ 그리고 $t_{90}$의 감소 경향이 관찰되었다. 본 연구에서 천연고무의 발포 가황특성의 최적 온도는 $165^{\circ}C$ 였으며 이때 발포된 천연고무 밀도가 가장 낮은 것으로 확인되었다. $145^{\circ}C$에서 발포된 천연고무발포체의 가교속도지수가 가장 작은 값을 보였다. 발포 천연고무의 발포 및 모폴로지 특성으로부터 발포체의 밀도 특성을 확인할 수 있었다. 고무내부에 생성된 각 발포 격벽의 두께는 발포온도가 증가함에 따라 감소하는 반면 카본블랙 함량 증가와 더불어 증가함을 보였다.

Keywords

References

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