ABSTRACT:In this study, three cationic surfactants (hexadecyltrimethylammonium chloride, hexadecyldimethylbenzylammonium chloride, and octadecyltrimethylammonium chloride) were used to modify montmorillonite and polyethylene (PE)/maleic anhydride grafted polyethylene (PE-g-MAH)/organic-montmorillonite (Org-MMT) nanocomposites, prepared by two blending processes (directmelt blending and solution blending). X-ray diffractometry and transmission electron microscopy were used to investigate the intercalation behavior and microstructure of composites. Mechanical properties were also tested. It was found that the intercalation effect of PE/PE-g-MAH/Org-MMT could be enhanced by increasing the content of PE-g-MMT, using the silicate modified by a cationic surfactant with a benzyl group or long alkyl chain, adopting the solutionblending method or using high-density polyethylene as matrix. The degree of crystallinity of composites and the crystalline thickness perpendicular to the crystalline plane [like (110) and (200)] decreased with increasing amounts of PEg-MAH and, under certain prescription, the crystalline thickness of the composite made by the solution method was much smaller than that made by direct-melt blending. This clearly showed that Org-MMT and PE-g-MAH had a heterogeneous nucleation effect on crystallization of PE from the melt, resulting in a decrease of crystalline thickness, and the heterogeneous nucleation effect was more evident in the nanocomposite made by the solution-blending method than in that made by the direct-melt intercalation process. The tensile strength initially increased and then decreased with increasing contents of PE-g-MAH. The maximum value in tensile strength (23.3 MPa) was achieved when the concentration of PE-g-MAH was 6 wt %. The impact strength increased concomitantly with the content of PE-g-MAH; it was 122.2 J/m when the concentration of PE-g-MAH was 9 wt %.

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A sensitive and reliable approach for the detection of the glass transition of polymers using AIE luminogens as fluorescent probes was reported.

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Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X-ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in ␥-crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami-Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed.

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Polypropylene (PP)/organo‐montmorillonite (Org‐MMT) nanocomposites toughened with maleated styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) were prepared via melt compounding. The structure, mechanical properties, and dynamic mechanical properties of PP/SEBS‐g‐MA blends and their nanocomposites were investigated by X‐ray diffraction (XRD), polarizing optical microscopy (POM), tensile, and impact tests. XRD traces showed that Org‐MMT promoted the formation of β‐phase PP. The degree of crystallinity of PP/SEBS‐g‐MA blends and their nanocomposites were determined from the wide angle X‐ray diffraction via profile fitting method. POM experiments revealed that Org‐MMT particles served as nucleating sites, resulting in a decrease of the spherulite size. The essential work of fracture approach was used to evaluate the tensile fracture toughness of the nanocomposites toughened with elastomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3112–3126, 2005