A modified clay was used to prepare poly(L-lactic acid)/clay nanocomposite dispersions. X-ray diffraction and transmission electron microscopy experiments revealed that poly(L-lactic acid) was able to intercalate the clay galleries. IR spectra of the poly(L-lactic acid)/ clay nanocomposites showed the presence of interactions between the exfoliated clay platelets and the poly(L-lactic acid). Thermogravimetric analysis and differential scanning calorimetry were performed to study the thermal behavior of the prepared composites. The properties of the poly(L-lactic acid)/clay nanocomposites were also examined as functions of the organoclay content. The exfoliated organoclay layers acted as nucleating agents, and as the organoclay content increased, the crystallization temperature increased.

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In this study, we modified montmorillonite (MMT) with dilauryl dimethyl ammonium bromide (DDAB) and then exfoliated the structures in a poly(L-lactic acid) (PLLA) matrix. We used polar optical microscopy and X-ray diffraction (XRD) to examine the morphologies of the resulting composites, differential scanning calorimetry to study the melting and crystallization behavior, and Fourier transform infrared (FTIR) and Raman spectroscopy to measure the influence of the intermolecular interactions between PLLA and MMT on the isothermal crystallization temperature. We found that the DDAB-modified MMT was distributed uniformly in the PLLA matrix. At temperatures ranging from 130 to 140 C, the crystalline morphology resembled smaller Maltese cross-patterned crystallites; at temperatures from 150 to 170 C, however, the number of crystallites decreased, their sizes increased, and they possessed ringed spherulite structures. In the XRD spectra, the intensity of the diffraction peaks of the 200/110 and 203 facets of the PLLA/MMT nanocomposites decreased as the crystallization temperature increased. In the FTIR spectra, the absorption peak of the C¼ ¼O groups split into two signals at 1748 and 1755 cm À1 when the isothermal crystallization temperature was higher than 140 C.

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ABSTRACT:We prepared a novel series of water-soluble silicone-modified polyesters [poly(ethylene glycol) (PEG)-silicone polyesters] by reacting organopolysiloxane with a hydroxy-terminated polyester. The polyesters were obtained by the polymerization of maleic anhydride and PEGs (molecular weights ϭ 2000, 4000, 6000, 8000, and 10000). These water-soluble PEG-silicone polyesters can be used as auxiliaries in dyeing process because they exhibit good surface activities such as surface tension, low foaming, and wetting power. The presence of these surfactants also retarded the rate of nylon dyeing with acid dyes. The retarding effect and low-foaming property of these novel PEGsilicone polyesters make it possible for these surfactants to be used as leveling agents for modern nylon dyeing with acid dyes.