In recent years the fractional calculus approach to describing dynamic processes in disordered or complex systems such as relaxation or dielectric behavior in polymers or photo bleaching recovery in biologic membranes has proved to be an extraordinarily successful tool. In this paper we apply fractional relaxation to filled polymer networks and investigate the dependence of the decisive occurring parameters on the filler content. As a result, the dynamics of such complex systems may be well–described by our fractional model whereby the parameters agree with known phenomenological models.
Unidirectional elongation of magnetic field sensitive polymer gels, called ferrogels, have been studied. In ferrogels, finely distributed colloidal particles having superparamagnetic behavior are incorporated into a swollen network. These particles couple the shape of the gel to the nonuniform magnetic field. Shape distortion occurs instantaneously and disappears when the external field is removed. A discontinuous elongation and contraction in response to infinite-small change in the external magnetic field has been observed and a theoretical interpretation based on coupled magnetic and rubber elastic properties is provided.
Articles you may be interested inMelting of α-Al2O3 and vitrification of the undercooled alumina liquid: Ab initio vibrational calculations and their thermodynamic implications J. Chem. Phys. 138, 064507 (2013); 10.1063/1.4790612 Microscopic structure and thermodynamics of a core-softened model fluid: Insights from grand canonical Monte Carlo simulations and integral equations theoryAtomic-force pictures reveal a heterogeneous microstructure at the surface of glassy layers which should be similar to one of the many equivalent microstructures a liquid is running through. These microstructures are described with the aid of a kinetic model of reversible aggregation which goes back to formulations as used in the description of living polymerization or aggregation of polymers in solution. Aggregates are considered as dynamic subsystems wherein collective modes of motions are excited. Fluctuations of the aggregates, densely packed in a disordered pattern, leads to a broad size distribution which happens to be controlled by Boltzmann's factor. The disordered structure within the aggregates themselves is optimized, reduced aggregate energy and entropy should be equal. Symmetries are deduced which elucidate many universal properties of the dynamic microstructure of liquids. Thermodynamic properties like the specific heats of aggregation in liquids or the dependence of the glass transition of homologues of linear atactic polystyrene are consistently described.
Crystallinity, mean crystal thickness, thickness distribution of crystals, and mean thickness of the amorphous layers in LDPE are deduced by treating it as a eutectoid copolymer. This knowledge is transferred into a van der Waals network theory which includes plastic shear deformation of crystals. The fit of stress-strain pattern a t different temperatures and of temperature induced relaxation and shrinkage informs about the deformation mechanism in semicrystalline polymers. Deformationsmechanismen bei grogen Dehnungen in partiell-kristallinen Polymeren -L D P EKristallanteil, mittlere Dicke der Kristalle, Dickenverteilung der Kristalle, Dicke der amorphen Bereiche in LDPE folgen aus seiner Beschreibung als eutektoides Copolymer. Diese Kenntnis wird in ein van der Waals-Kristallnetzwerk-model1 iibernommen, welchcs die plastische Scherdeformation der Kristalle einschlieBt. Die Wiedergahe der Spannungs-Dehnungs-Kurven bei verschiedenen Temperaturen und der temperaturinduzierten Ruckstellung fuhrt zu einer Identifikation von Deformationsmechanismeii in teilweise kristallisierten Polymeren.
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