Nanocomposites based on epoxy and nanoclay were prepared employing organically modified mica type silicate (OMTS), diglycidyl ether of bisphenol A (DGEBA) type epoxy, curing agent(dicyandiamide; DICY), and catalyst(benzyl dimethyl amine; BDMA). Both melt mixing and solution mixing were used for the sample preparation and structural developments with curing reaction were analyzed using X-ray diffractometer (XRD) and small angle X-ray scattering (SAXS). Because of the different curing rate between extra-gal-lery and intra-gallery reactions of epoxy mixtures, only intercalated structure was observed for the sample prepared by melt mixing while fully exfoliated structure was observed for the sample prepared by solution mixing. Mechanical properties of exfoliated epoxy nanocomposite were investigated using a dynamic mechanical analyzer (DMA). The dynamic storage modulus of the nanocomposite in both glass and rubbery plateau regions were increased with increasing OMTS contents, but glass transition temperatures (T(g)) remained unchanged. Thermal properties of epoxy nanocomposite were investigated using thermogravimetric(TGA) and limit oxygen index(LOI) methods. Thermal decomposition onset points and LOI values were increased with increasing OMTS contents due to barrier effects of OMTS sheets.

에폭시(diglycidyl ether of bisphenol A; DGEBA), 경화제 (dicyandiamide; DICY), 촉매(benzyl dimethyl amine; BDMA), 그리고 유기치환된 실리케이트(organically modified mica type silicate; OMTS)를 용융법 및 용액법을 이용해 나노복합체를 제조하였고, 170 ℃에서 시간에 따라 경화 반응을 진행하면서 X선 회절분석기 (XRD)와 소각 X선 산란장치 (SAXS)를 이용하여 구조 변화를 관찰하였다. 용융법으로 제조된 시료의 경우 박리된 구조를 관찰할 수 없었으나 용액법에 의해 제조된 경우 박리된 구조를 관찰할 수 있었다. 이는 OMTS 층 내·외부의 경화 속도차이 때문인 것으로 생각된다. 박리된 에폭시 나노복합체의 OMTS 첨가량에 따른 기계적 물성을 동적기계적 분석기 (DMA)를 이용해 측정한 결과 OMTS의 첨가량이 증가할수록 모둘러스는 증가하였으나 유리전이온도는 큰 차이가 없었다. OMTS 첨가량에 따른 열적 성질을 열중량분석기 (TGA)와 한계산소지수 (LOI)를 이용해 측정한 결과 OMTS양이 증가할수록 OMTS 판의 차단효과로 인해 열분해 시작 온도와 LOI 값이 증가하였다.

Keywords: epoxy nanocomposite; OMTS; exfoliation; mechanical property; thermal property