Structure and crystallization behaviour of poly(ε-caprolactone)/clay intercalated nanocomposites

Nanocomposites of poly(epsilon-caprolactone)/M-HTAB were obtained by polymerization of caprolactone with various amounts (10, 30, 50 and 64 weight ratio) of montmorillonite organophilized with hexadecyltrimethylammonium bromide (HTAB). The microstructure of nanocomposites was studied by small angle X-ray scattering (SAXS). Additionally, the melting enthalpies (DeltaH(m)), the crystallinities and the half-time of isothermal crystallization were evaluated by differential scanning calorimetry (DSC). As a result of SAXS experiments for the composite PCL/M-HTAB 90/10, in the temperature range from 313 to 283 K, a rapid change in the interlamellar distance from 3.1 nm to 2.72 nm was observed. Similar scattering curves were obtained for the nanocomposite PCL/M-HTAB 70/30. In the composites containing 50% and 64% wt of M-HTAB, the decrease in interlayer distance was less pronounced in the same temperature range (d(001) 3.15 - 3.2 nm). DSC results clearly showed that the crystallization is divided into two separate processes: primary crystallization in the PCL matrix, and secondary crystallization.