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The development of capsules with additives that can be added to polymers during extrusion processing can lead to advances in the manufacturing of textile fabrics with improved and durable properties. In this work, caffeine (CAF), which has anti-cellulite properties, has been encapsulated by liquid-assisted milling in zirconium-based metal–organic frameworks (MOFs) with different textural properties and chemical functionalization: commercial UiO-66, UiO-66 synthesized without solvents, and UiO-66-NH2 synthesized in ethanol. The CAF@MOF capsules obtained through the grinding procedure have been added during the extrusion process to recycled polyamide 6 (PA6) and to a biopolymer based on polylactic acid (PLA) to obtain a load of approximately 2.5 wt% of caffeine. The materials have been characterized by various techniques (XRD, NMR, TGA, FTIR, nitrogen sorption, UV–vis, SEM, and TEM) that confirm the caffeine encapsulation, the preservation of caffeine during the extrusion process, and the good contact between the polymer and the MOF. Studies of the capsules and PA6 polymer+capsules composites have shown that release is slower when caffeine is encapsulated than when it is free, and the textural properties of UiO-66 influence the release more prominently than the NH2 group. However, an interaction is established between the biopolymer PLA and caffeine that delays the release of the additive. [ABSTRACT FROM AUTHOR]

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In clay polymer nanocomposite technology, nowadays there is concern about the safety and environmental effects of the nanometric materials. In this work, sheets of layered titanosilicate JDF-L1 were synthesized with a size of 5.3 μm and thickness of 115 nm and used to fabricate composite polyamide 6 (PA6) films. The JDF-L1 synthesis was scaled in one pot and the rosette-like particles obtained were disaggregated using a simple process with NaOH solution. The composite with 2 wt.% of disaggregated JDF-L1, characterized by X-ray diffraction and electron microscopy, showed parallel orientation (with respect to the film itself) and good dispersion of the sheets. The composite had a similar barrier effect as the PA6 and its mechanical properties did not deteriorate. This opens up the use of this composite as a packing material providing other properties, such as a biocidal effect and synergy effect in combination with other additives. [ABSTRACT FROM AUTHOR]

MFI-type zeolite membranes prepared on stainless steel and alumina tubular supports were used to separate a CO/air mixture at very low CO concentrations (160 ppbv). The influence of the temperature, pressure gradient across the membrane, sweep gas and retentate gas flow rates in the performance of the membranes was studied. At 245 K, a CO/air separation factor of 3.14 was achieved. [Copyright &y& Elsevier]

Gel permeation chromatography with differential refractometry is used to obtain molecular weight distributions (MWD) of poly-(epsilon-caprolactams). Elution is carried out using an m-cresolchlorobenzene mixture (50:50, v/v) at 50 degrees C. MW values are obtained by a Hamielec-based calibration method, using broad-MWD poly-(epsilon-caprolactam) standards with the same chemical nature and similar MWD to the samples. Relative errors for the number-average MW (Mn) using this calibration method range from 0.4% (in the low polyamide MW range) to 20% (in the high polyamide MW range). These values are much lower than those obtained from narrow-MWD polystyrene calibration, which range from 39% to 78%. Similar values have been obtained for the other usual average MW parameters. The ability to obtain repeatability parameters for a given confidence interval and the utilization of statistical criteria for chromatogram rejection allow this method to be used in quality control for MWD of poly-(epsilon-caprolactams). Thus, production variables are related to polyamide-6 behavior in its ulterior treatment. Typical relative standard deviation percentages (for n=6) of a polyamide sample range from 1.9% (for Mn) to 3.3% (for M(z+1)).