Influence of hydrogen bonds on glass transition and dielectric relaxations of cellulose

The molecular dynamics in hydrated cellulose has been investigated by a combination of thermal analyses and dielectric spectroscopy. Differential scanning calorimetry shows the dependence upon hydration of the glass transition temperature Tg. A physical ageing phenomenon has been observed. At the molecular scale, bound water is hydrogen bonded to polar sites of cellulose macromolecules. At the macroscopic scale, water molecules play the role of a plasticizer for cellulose lowering its Tg. Dynamic dielectric spectroscopy combined with thermostimulated currents have allowed us to follow more localized molecular mobility. The β relaxation mode is characterized by activation entropies that vanish for higher water contents indicating molecular mobility localization. It is plasticized by water like the glass transition. This analogy is explained by a common origin of both mechanisms: the mobility of the cellulose backbone. The evolution of the γ mode upon hydration follows an anti-compensation law. Water acts as an anti-plasticizer in a hydrogen bonded network

Molecular mobility in piezoelectric hybrid nanocomposites with 0-3 connectivity: Particles size influence

Polyamide 11/barium titanate nanocomposites have been studied by a combination of dynamic dielectric spectroscopy, thermo stimulated current and differential scanning calorimetry. The correlation between results obtained by dielectric and calorimetric methods allows us to describe the evolution of the physical structure of the hybrid nanocomposites. The molecular mobility of 0-3 connectivity nanocomposites has been explored. The influence of the nanoparticles size is specifically studied. The smaller sized fillers produce a shift of the relaxation modes observed above the glass transition temperature of polyamide 11 towards lower frequency. The increase of the organic/inorganic interface induces an increase of the ratio rigid amorphous phase/soft amorphous phase. The interfaces favour local ordering stabilized by hydrogen bonds at a nanometric scale

La enseñanza del derecho en los sistemas legales islámico, judío y zoroástrico

Analiza a la luz de la enseñanza del derecho las semejanzas y diferencias de los sistemas jurídicos islámico, judío y zoroástrico. El estudio permite así contemplar las relaciones y desencuentros que se dan entre estas tradiciones jurídicas orientales.Legal education in Islamic, Jewish and Zoroastrian law. The similarities and differences between the Islamic, Jewish and Zoroastrian legal systems are discussed in the light of their legal education. The study allows a gaze at the correspondences and variances between those three oriental juridical traditions

Electroactive influence of ferroelectric nanofillers on polyamide 11 matrix properties

Barium titanate ceramic powders have been incorporated in polyamide 11 to form homogeneous dispersion of particles in the matrix. Barium titanate/polyamide 11 nanocomposites have been synthesized using a solvent casting method with ultrasonic stirring to homogeneously disperse inclusions in the matrix. Composites with volume fraction of barium titanate / ranging from 0.01 to 0.4 were elaborated. Films were fabricated using a hot press method. Only the inclusions were poled in the matrix to form a ferroelectric particles/ unpoled matrix composite. Interactions between the particles and the matrix, pyroelectric and piezoelectric response were studied as a function of / by dynamic dielectric spectroscopy. Composites show interesting pyro-piezoelectric activity. Pyroelectric merit factor increases linearly and it reaches a limit value of 0.3 for a volume fraction / = 0.1

Physical structure of P(VDF-TrFE)/barium titanate submicron composites

Dynamic Dielectric Spectroscopy and Thermo Stimulated Current were used to investigate of the dielectric relaxation of hybrid Poly(vinylidene-fluoride-trifluoroethylene)/barium titanate 700 nm composites with 0–3 connectivity. The results obtained by this method allow us to describe the physical structure of these composites in the glassy state at a nanometric scale. The decrease of the activation enthalpies and activation entropies involved in the dynamics of the α relaxation is attributed to: the decrease of Cooperative Rearranging Region sizes and an increase of intra/inter macromolecular interactions in the amorphous phase with the volume fraction

Coming Home: The Bruderhof Returns to Germany

The Bruderhof Community, founded by Eberhard Arnold in Germany shortly after World War I, envisions communal life according to the principles of early Anabaptism, Christian Socialism, and the German Youth Movement. Persecuted by the National Socialists in the 1930s, the group migrated to America. Despite harassment and expulsion from Germany, it has attempted to reunite with its geographic birthplace. Reasons for continued efforts to reconnect to the German homeland can be found in the movement’s historical development as a free church with a global awareness and outreach. Analyzing the Bruderhof’s experience with persecution, its distinct theology, and perseverance as a communal order, I explore the motivations that led to the community’s resettlement in Germany and the consequences of that endeavor