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Natural rubber (NR)-montmorillonite (MMT) nanocomposites were prepared by a novel in situ organomodified and latex compounding method, followed by melt compounding technique. Effects of cationic surfactant on MMT dispersion, curing characteristic, mechanical, and dynamical properties were investigated. The number of layers in the layered MMT stack was determined by Small-Angle X-Ray Scattering (SAXS). The dispersion of MMT tends to form high ordered structure in NR-MMT masterbatch when cationic surfactant of more than 4 phr was used. The morphology of Na-MMT shows partly intercalated and exfoliated structure in the matrix after mixing and hot pressing process with reduced number of layers compared to the pristine MMT. The use of cationic surfactant over 4 phr introduces a plasticizing effect resulting in the reduction of crosslink density, hardness and modulus, but increase in tensile strength due to higher interfacial adhesion between NR and MMT as determined by Maeir-Goritz model and Field Emission Scanning Electron Microscopy (FESEM). The optimum cationic surfactant loading is observed at 4 phr with the highest stable bonds, which result in the highest crosslink density, tear strength and storage modulus while the lowest Payne effect and tan delta at 60[degrees]C., INTRODUCTION After the successful work of Toyota research groups on the preparation of polyamide 6 (PA6)-montmorillonite (MMT) nanocomposites [1]. layered silicate has been increasingly used as reinforcing filler for rubbers [...]

In this study, the influences of processing conditions, that is, injection speed and holding pressure, on the gradient crystal structural formation in the injection‐molded cap specimens were investigated. Skin‐, shear‐ and core‐layers across the specimen thickness were investigated in detail by using small‐angle x‐ray scattering, wide‐angle x‐ray diffraction, and atomic force microscopy techniques. The results showed that high holding pressure caused high density and large weight of the cap specimens. This strongly contributed to high displacement resistant on applied pressure (doming resistant), while the lamellar thickness (Lc) of the skin layer also played a role. On the contrary, low holding pressure promoted the formation of the random‐oriented lamellae in the core layer, which contributed to high environmental cracking resistance (ESCR). Moreover, the lower injection speed caused the thicker Lc of the skin layer, and this improved the ESCR of the specimen. The results allowed us to propose its failure mechanism. [ABSTRACT FROM AUTHOR]

Cubosomes and other lyotropic liquid crystal (LLC) phases are of great interest in many fields due to their potential as delivery systems. This study prepared poloxamer 188 (Pluronic® F68 [F68]) based cubosomes utilizing a low energy method and reports LLC structure stability, rheological behavior and carrier properties of the formed cubosomes. Mixtures of F68 and water were investigated and showed a concentration dependent viscoelastic behavior, ranging from a viscous liquid (30% F68) to hard gels (70% F68). Small‐angle X‐ray scattering showed cubosomes (Im3m) were present at F68 concentrations between 45% and 60%. Cubosomes fabricated from 50% F68 and 50% water were selected as the best composition and gave stable cubic structures for at least 10 months without additional stabilizing agent. To assess the use with poor water‐soluble molecules, artocarpin (AR) was added to the F68‐based cubosome. The developed cubosome possessed enhanced AR solubility due to the high affinity to the hydrophobic regions present in the cubic formation. Furthermore, an in vitro permeation study showed faster permeation rates of the developed cubosomes when compared to a cream‐based formulation. Collectively, these findings demonstrate that the F68‐based cubosomes represent a promising low‐cost active carrier for enhancing the solubility and permeability of low water‐soluble molecules. [ABSTRACT FROM AUTHOR]

The size distribution of gold hydrosol aggregates induced by ascorbic acid has been characterised by small angle x-ray scattering (SAXS). The results are used to compute the extinction coefficients around the localised surface plasmon resonance (LSPR) wavelengths and verified by comparing experimental extinction spectra obtained via spectrophotometry. Citrate refluxed gold nanoparticles with initial ionic ratio of 0.94 measured by fitting an averaged intensity profile from two scattering lengths exhibit lognormal distribution with mean diameter of 27.4 nm (σd = 14.4 nm), while ascorbic acid induced agglomeration on gold nanoparticles at pH of 3.2 has mean diameter of 51.2 nm (σd = 19.2 nm). Both experiment and simulated optical extinction shows agreement in LSPR peak wavelength corresponding to their respective mean particle sizes. [ABSTRACT FROM AUTHOR]

A synchrotron small-angle X-ray scattering (SAXS) study on PVA/Fe3O4 magnetic hydrogels has been performed to investigate the effect of clustering on their magnetic properties. The hydrogels were prepared through freezing-thawing (F-T) processes. The structure, morphology and magnetic properties of magnetite (Fe3O4) nanoparticles (NPs) were investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer, respectively. In this study, SAXS data were used to reveal the structural dimensions of the magnetite and its distribution in the polymer-rich PVA and magnetic hydrogels. As calculated using the Beaucage and Teubner-Strey models, the average of the structural dimensions of the PVA hydrogels was 3.9nm (crystallites), while the average distance between crystallites was approximately 18nm. Further analysis by applying a two-lognormal distribution showed that the magnetite NPs comprised secondary particles with a diameter of 9.6nm that were structured by primary particles (3.2nm). A two-lognormal distribution function has also been used in describing the size distributions of magnetite NPs in magnetic hydrogels. The clusters of magnetite NPs in the magnetic hydrogels are significantly reduced from 30.4nm to 12.8nm with decreasing concentration of the NPs magnetite from 15wt.% to 1wt.%. The saturation magnetization values of the magnetite NPs, the 15% and 1% magnetic hydrogels were 34.67emu/g, 6.52emu/g and 0.37emu/g, respectively. The PVA/Fe3O4 magnetic hydrogels were successfully fabricated by freezing-thawing processes. The structures were investigated by using small angle X-ray scattering. The secondary particles and clusters of magnetite nanoparticles in the magnetic hydrogels fitted by two lognormal distributions presented clustering degradation with lowering Fe3O4 composition. Furthermore, the effect of clustering on the magnetic properties was also performed by means of SQUID magnetometer. The saturation magnetization of the magnetic hydrogels is proportional to the Fe3O4 composition and also their clusters. [ABSTRACT FROM AUTHOR]