Thermally driven adsorption chillers and heat pumps are a very promising approach toward an efficient use of energy as well as an effective climate protection through reduced CO2 emission of conventional heating and cooling devices. With regard to current market entrance of this technology, this paper presents results on the stability of current available materials like silica gels and zeolites, recently developed materials like aluminophosphates (AlPO) and silica-aluminophosphates (SAPO) and novel materials like metal organic frameworks (MOF) under hydrothermal treatment.Seven materials as powders or granules as well as three composite have been analyzed under continuous thermal cycling in a water vapour atmosphere in order to evaluate their suitability for the use in a periodically working heat pump with water as working fluid.The stability of powders has been analyzed in-situ by thermogravimetry in a first stage short-cycle test. In case of the composite, made up of an active sorption material and a support structure, a cycling-test rig has been developed in order to realize a life-cycle stress. The need for a first stage short-cycle test is demonstrated impressively by the dramatic loss of 40% in sorption capacity of a Cu-BTC sample within the first 15 cycles

Emulsifier-free aqueous dispersions of functionalized graphene (FG) represent key intermediates for the production of rubber composites, enabling uniform dispersion of predominantly single FG sheets. In this comparative study on styrene-butadiene rubber (SBR) composites with conventional and novel carbon-based fillers the influence of filler type, content, and dispersion process is examined. For SBR/FG nanocomposites two aqueous dispersion blend strategies based on thermally and chemically reduced graphite oxide are explored. Electron microscopy and X-ray tomography confirm the highly effective FG dispersion in SBR leading to simultaneous improvement of mechanical properties, electrical conductivity, and gas barrier resistance.

A state-of-the-art, medium-resolution H-NMR spectrometer (62 MHz) is used as a chemically sensitive online detector for size-exclusion chromatography of polymers such as polymethylmethacrylate (PMMA) and polystyrene (PS). The method uses protonated eluents and works at typical chromatographic conditions with trace amounts of analytes (<0.5 g L after separation). Strong solvent suppression, e.g., by a factor of 500, is achieved by means of T -filtering and mathematical subtraction methods. Substantial improvements are made with respect to previous work in terms of the sensitivity (signal-to-noise ratio up to 130:1, PMMA OCH ) and selectivity (peak width, full width half maximum (FWHM) 4 Hz on-flow). Typical homopolymers and a blend are investigated to deformulate their composition along the dimensions of molecular weight and NMR chemical shift. These results validate this new hyphenated chromatography method, which can greatly facilitate analysis and is much more effective than previously published results.

This paper describes the production of graphene nanocomposites via melt mixing of thermally reduced graphite oxide with ethylene vinyl‐acetate copolymers of different (0–70 wt%) vinyl acetate content, and their measured electrical and rheological properties. The aim of these studies was to investigate the influence of a continually changing polymer matrix polarity on the dispersion and percolating behavior of graphene fillers, an effect that can be expected to be most prominent with the high specific surfaces of the latter. Composites with graphite and multi‐walled carbon nanotubes were produced and examined for comparison. The effectivity of the dispersion process was checked by measuring the melt rheology and electrical conductivity of the samples. The percolation thresholds derived from these measurements show a minimum for VA contents around 20 wt%. The thresholds for electrical conductivity are by a factor around 1.5 lower than the rheological values, and both are distinctively higher than those observed from composites produced via solution mixing. The percolation behavior is compared to predictions made from the surface energy of the compounds.

Time-domain NMR is a well known tool for assessing the molecular dynamics in soft matter by measuring the excitation and subsequent decay of 1H nuclear magnetization. It is widely used, e.g., to quantify the composition of heterogeneous soft matter systems like semicrystalline polymers or emulsions. Further applications, known from academic research and industrial application, include measuring the moisture content in solids, the residual magnetic dipolar coupling for quantifying molecular motion in crosslinked systems, or diffusometry. We report the integration of a permanent magnet based pulsed NMR spectrometer into a modern, commercially available high-end shear rheometer. The setup allows for the first time to simultaneously conduct time-domain 1H NMR and steady shear or dynamic rheological measurements on one sample and to directly correlate the results from both, without concerns about differences in the sample history or temperature calibration. Moreover, the new in-situ combination allows the full usage of the rheometer to apply nonlinear deformation, under steady shear or large amplitude oscillatory shear, and directly measure the effect on the time evolution of the sample properties. This publication introduces the technical setup of this novel instrument combination and describes the shear induced crystallization of polyolefins to demonstrate its capabilities. Further potential applications are outlined.

Semi crystalline polymers play an enormously important role in materials science, engineering, and nature. Two thirds of all synthetic polymers have the ability to crystallize which allows for the extensive use of these materials in a variety of applications as molded parts, films, or fibers. Here, we present a study on the applicability of benchtop 1 H NMR relaxometry to obtain information on the bulk crystal linity and crystallization kinetics of the most relevant synthetic semi crystalline polymers. In the first part, we investigated the temperature dependent relaxation behavior and identified T ¼ T g þ 100 K as the minimum relative temperature difference with respect to T g for which the mobility contrast between crystalline and amorphous protons is sufficient for an unambiguous determination of polymer crystal linity. The obtained bulk crystallinities from 1 H NMR were compared to results from DSC and XRD, and all three methods showed relatively good agreement for all polymers. In the second part, we focused on the determination of the crystallization kinetics, i.e., monitoring of isothermal crystallization, which required a robust design of the pulse sequence, precise temperature calibration, and careful data analysis. We found the combination of a magic sandwich echo (MSE) with a short acquisition time followed by a Carr Purcell Meiboom Gill (CPMG) echo train with short pulse timings to be the most suitable for monitoring crystallization. This study demonstrates the application of benchtop 1 H NMR relaxometry to investigate the bulk crystallinity and crystallization kinetics of polymers, which can lead to its optimal use as an in situ technique in research, quality control, and processing labs.

Rheological set‐ups with in situ analytical sensors, combine information on the flow and deformation behavior of soft matter, with simultaneous insights into structural and dynamic features. Furthermore, they permit the study of soft matter under well‐defined flow conditions. Herein are presented hyphenations of rheology and nuclear magnetic resonance (NMR), small angle X‐ray scattering (SAXS), and optical microscopy. They are employed to unravel relationships between the molecular dynamics, morphology, and rheology of crystallizing polymers. The results confirm a physical gelation process during polymer crystallization, mediated by the interaction of growing superstructures at volume fractions of 10–15%. The buildup of row‐nucleated structures during flow‐induced crystallization is found to reduce the time of gelation as detected by the rheological response. These investigations help to clarify the crystallization mechanism, structure–property relationships, and the hardening behavior of crystallizing polymers.

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