Polypropylene (PP)-clay hybrids (PPCH) have been prepared by simple melt-mixing of three components, i.e., PP, maleic anhydride modified polypropylene oligomers (PP-MA), and clays intercalated with stearylammonium. The dispersibility of 10-Å-thick silicate layers of the clays in the hybrids was investigated by using a transmission electron microscope and X-ray diffractometer. It is found that there are two important factors to achieve the exfoliated and homogeneous dispersion of the layers in the hybrids: (1) the intercalation capability of the oligomers in the layers and (2) the miscibility of the oligomers with PP. Almost complete hybrids were obtained in the case where the PP-MA has both intercalation capability and miscibility. The hybrids exhibit higher storage moduli compared to those of PP especially in the temperature range from Tg to 90°C. The highest relative storage modulus at 80°C of the hybrid based on a mica and the miscible PP-MA is as high as 2.0 to that of PP and is 2.4 to that of the PP/PP-MA mixture, which is considered to be the matrix of the PPCH. Also, the effects of the kinds of clays and oligomers on the dynamic moduli are discussed.

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Polypropylene–clay hybrids (PPCHs) were prepared by melt blending maleic anhydride modified PP and organophilic clay. In these PPCHs the silicate layers of the clay were exfoliated and dispersed to the monolayers. The hybridization of the clay in PP was achieved with modified PP with a small amount of maleic anhydride groups. The tensile modulus of the PPCH with 5 wt % clay was 1.9 times higher than that of the matrix resin at 25°C. The dynamic storage moduli (E′) of the PPCHs were also higher than those of the modified PP. The E′ was 2.5 times higher than that of the matrix resin at 60°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1918–1922, 2000

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Polystyrene-clay hybrids (PSCHs) were prepared by melt blending a styrene vinyloxazoline copolymer with organophilic clay. In the PSCHs, the silicate layers of the clay were delaminated and dispersed homogeneously to the nanometer level. The moduli of the PSCHs were higher than that of the PS copolymer. For example, the tensile modulus of the PSCH with 5 wt % clay was 1.4 times higher compared to that of the PS copolymer.

Green nanocomposites based on renewable plant oils have been developed. Curing of epoxidized plant oils in the presence of organophilic montmorillonite produced triglyceride−clay nanocomposites showing flexible property. A nanocomposite with homogeneous structure was obtained, in which silicate layers of the clay were intercalated and randomly distributed in the polymer matrix.

IntroductionIn recent years, organic-inorganic nanometer-composites have attracted great interest to researchers since they frequently exhibit unexpected hybrid properties synergistically derived from the two components. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] One of the most promising composite system would be hybrids based on organic polymers and inorganic clay minerals consisting of silicate layers [4][5][6][7][8][9][10][11][12][13][14][15][16][17] . In our previous works, we have synthesized nylon 6-clay hybrid (NCH) in which 1 nm thick silicate layers of clay minerals are exfoliated and homogeneously dispersed in the nylon 6 matrix. [5] The NCH exhibits various superior properties such as high strength, high modulus, and high heat resistance, compared to conventional nylon 6. [6] Since then, other polymer-clay hybrids such as polyimide, [7] epoxy resin, [8] polystyrene, [9] polycaprolactone, [10] acrylic polymer, [11] polyurethane, [12] and poly(ethylene terephthalate) [13] were reported. However, the dispersion of exfoliated silicates was achieved only in a few cases, i. e., nylon, [5,6] polyimide, [7] epoxy resin, [8] and polystyrene. [9 d, e] Polyolefins, i. e., poly(propylene) (PP), polyethylene (PE), ethylene-propylene rubber (EPR), are the most widely used polymers. However, there was few report of polyolefin-clay hybrids in which the silicate layers were exfoliated and homogeneously dispersed. It has been considered that the silicate layers of the clay have high polarity and are incompatible with polyolefins. Coates [14] and Mülhaupt [15] independently reported the in-situ olefin polymerization in the existence of organophilic clay to afford polyolefin-clay nanocomposites wherein the polyolefins were intercalated into the clay galleries. Recently, we have found polyolefin oligomers with polar functionality were intercalated into the organophilic clay galleries during melt-blending and these phenomena were the key to achieve the dispersion of exfoliated silicates in polyolefins. [16] We reported that PP and organophilic clay were melt-blended in the presence of maleic anhydride modified PP oligomer to obtained PP-clay hybrids wherein a large fraction of the clay silicates were found to be exfoliated. Since then, this system using modified PP oligomers as the compatibilizer was investigated by many researchers. [17] In this study we report a novel and general approach to prepare polyolefin-clay hybrids by using organophilic clay and maleic anhydride modified polyolefins during melt-blending and examine the morphologies and the basic properties of the hybrids. Results and discussionAll samples of polyolefin-clay hybrids were prepared by melt-blending maleic anhydride modified polyolefins and organophilic clay above each melting point. On the Full Paper: A novel and general approach to prepare polyolefin-clay hybrids by using the maleic anhydride modified polyolefins and organophilic clay during meltblending was reported. The silicate layers of the clay were exfoliated and homogen...

The dehydrogenative polymerization of coniferyl alcohol by horseradish peroxidase was performed in 0.10 M phosphate buffer at 27 degrees C. Dehydrogenative polymer (DHP) from coniferyl alcohol was characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. The ratio of 8-O-4':8-5':8-8' linkages was determined by the 1H NMR spectrum of DHP acetate which had good solubility. In "end-wise like" polymerization (the slow addition of hydrogen peroxide), addition of alpha-cyclodextrin to the medium led to DHP with increased 8-O-4' content and a decrease in 8-5' linkages. Under higher pH conditions, DHP with higher 8-O-4' and 8-5' content was obtained in the presence of alpha-cyclodextrin. In the end-wise polymerization (the slow additions of coniferyl alcohol and hydrogen peroxide), using alpha-cyclodextrin also gave DHP with a 8-O-4' richer structure than that prepared in no additive system. The analysis of thioacidolysis products from DHP supported the results of the alpha-cyclodextrin effects on the 8-O-4'-rich structure of DHP. The 8-O-4' structure in DHP prepared in the presence of alpha-cyclodextrin had racemic form as shown by ozonation.