Nonisothermal crystallization behavior of exfoliated poly(ethylene terephthalate)-layered silicate nanocomposites in the presence and absence of organic modifier

다국어 초록 (Multilingual Abstract)

<P>Exfoliated poly(ethylene terephthalate) (PET)-layered silicate nanocomposites (P<SUB>et</SUB>LSNs) excluding (P<SUB>et</SUB>LSN<SUB>eom</SUB>) and including (P<SUB>et</SUB>LSN<SUB>iom</SUB>) organic modifiers were obtained by solution methods with and without solvent-nonsolvent system, respectively. From wide angle X-ray diffraction and high resolution transmission electron microscopy, both P<SUB>et</SUB>LSNs were found to have exfoliated structure attributed to sufficient dispersion of silicate in prepared solvents, regardless of sample preparation method. However, organic modifier in P<SUB>et</SUB>LSN<SUB>eom</SUB> was confirmed to be well removed by elemental analysis, whereas organic modifier was still remained in P<SUB>et</SUB>LSN<SUB>iom</SUB>. Thus, the effect of the presence and absence of organic modifiers in P<SUB>et</SUB>LSNs on the nonisothermal crystallization behavior was investigated by differential scanning calorimetry (DSC) on the basis of a modified Avrami analysis and polarized optical microscopy (POM). From DSC results, it was found that both P<SUB>et</SUB>LSNs had higher degrees of crystallinity and shorter crystallization half-times than neat PET, because of the dispersed silicate layers acted as nucleating agents in both P<SUB>et</SUB>LSNs. However, P<SUB>et</SUB>LSN<SUB>iom</SUB> exhibited a lower degree of crystallinity and longer half-time of crystallization than P<SUB>et</SUB>LSN<SUB>eom</SUB>. Difference of crystallization behavior between P<SUB>et</SUB>LSN<SUB>eom</SUB> and P<SUB>et</SUB>LSN<SUB>iom</SUB> was ascribed to organic modifier in P<SUB>et</SUB>LSN<SUB>iom</SUB>, which may act as crystallization inhibitors. POM measurements also revealed the results which were in good agreement with crystallization behavior observed from DSC measurement. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 989–999, 2008</P>