Some thermodynamic quantities of n-alkanes as a function of chain length

Summary Results from high pressure dilatometry onn-alkanes and linear polyethylene and literature data yield a linear relation between specific volume, entropy and enthalpy of fusion, the reciprocal melting temperature and 1/n, wheren denotes the number of C-atoms per molecule. Extrapolating towards infiniten one always obtains polyethylene data.The differences in the properties ofn-alkanes and polyethylene can be ascribed to the influence of the chain ends. Assuming entropy and enthalpy contributions from these chain ends as made probable by a molecular model one can quantitatively explain then-dependence of the above mentioned quantities including their pressure dependence.With 10 figures and 2 tables     

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Synchrotron Microbeam Diffraction Study of the Microstructure and the Chemical Composition in a Monocrystalline Ni-Base Turbine Blade After a Thermomechanical Mission Test

High-performance turbine blades composed of monocrystalline Ni-base / superalloys are often protected by coatings to resist the high-temperature corrosive atmosphere environment applications. During applications severe thermal and mechanical loads cause drastic and complicated changes in the microstructure and the chemical composition, also combined with strong lateral gradients of both temperature and stress. Microbeam X-ray diffraction experiments with a spatial resolution of about 5 m enabled the determination of both the microstructural and the chemical composition gradients within material volumes of the sizes of the order of about 1 mm³ or smaller. The high angular and spatial resolution was achieved by a special focusing technique using a Bragg–Fresnel focusing monochromator at the BM5 beamline of the ESRF synchrotron at Grenoble. The X-ray diffraction experiments were complemented and supported by electron microscopy investigations of the microstructure and the chemical composition.     

Linear response in chaotic states of discrete dynamics

The importance of the coupling operatorA of an external disturbance to a 1-dimensional map is discussed. A time dependent susceptibility _t ^BA is introduced describing the linear response in chaotic states observed with observableB. Its properties are given, its temporal decay, and its relation to correlations (fluctuations). Some examples are evaluated explicitely. The static susceptibility depends on the correlation decay as usual, and diverges if the state changes its character under the perturbation.     

Depolymerization of Polyethylene Using Induction-Coupled Plasma Technology

A significant, valuable percentage of today's municipal solid wastestream consists of polymeric materials, for which almost no economicrecycling technology currently exists. This polymeric waste is incinerated,landfilled, or recycled via downgraded usage. Thermal plasma treatment is apotentially viable means of recycling these materials by converting themback into monomers or into other useful compounds. The technical, laboratoryscale, feasibility of using an induction-coupled RF plasma (ICP) heatedreactor for this purpose has been demonstrated in the presentstudy. Polyethylene powder was injected axially through the center of anICP torch. Results from the initial set of experiments, analyzed using astatistical design of experiment technique, showed that plasma plate power,central gas flow rate, probe gas flow rate, powder feed rate, and theinteraction between the quench gas flow rate and power input were the keyprocess parameters affecting the yield of ethylene in the product gasstream. The gaseous products obtained were mainly mixtures of ethylene andpropylene. The amount of propylene obtained was significantly higher thananticipated and was believed to be due to -scission reactionsoccurring at the higher plasma temperatures.