Investigations on electric conductivity have been performed on polycarbonate (PC) containing 0.6 vol% of multi-walled carbon nanotubes (MWNT) in a rheometer, where the plates act as capacitor plates for dielectric spectroscopy. The time dependent recovery of the DC-conductivity was recorded in the rest time after a transient shear deformation. The DC-conductivity shows a tremendous increase with the time after shearing. This conductivity recovery is explained by the reorganization of the conducting MWNTnetwork, which was destroyed by the shear. The reformation kinetics of MWNT-clusters is considered as a cooperative cluster-cluster aggregation coupled to electrical percolation of conductive MWNT.
The forward effect of testing refers to the finding that retrieval practice of previously studied information increases retention of subsequently studied other information. It has recently been hypothesized that the forward effect (partly) reflects the result of a reset-of-encoding (ROE) process. The proposal is that encoding efficacy decreases with an increase in study material, but testing of previously studied information resets the encoding process and makes the encoding of the subsequently studied information as effective as the encoding of the previously studied information. The goal of the present study was to verify the ROE hypothesis on an item level basis. An experiment is reported that examined the effects of testing in comparison to restudy on items’ serial position curves. Participants studied three lists of items in each condition. In the testing condition, participants were tested immediately on non-target lists 1 and 2, whereas in the restudy condition, they restudied lists 1 and 2. In both conditions, participants were tested immediately on target list 3. Influences of condition and items’ serial learning position on list 3 recall were analyzed. The results showed the forward effect of testing and furthermore that this effect varies with items’ serial list position. Early target list items at list primacy positions showed a larger enhancement effect than middle and late target list items at non-primacy positions. The results are consistent with the ROE hypothesis on an item level basis. The generalizability of the ROE hypothesis across different experimental tasks, like the list-method directed-forgetting task, is discussed.
We present results of in situ measurements of the filling process of polymer melts in nanopores. After accurate characterization of the empty nanopores, they are filled with the hydrophobic polyisobutylene and the hydrophilic poly-epsilon-caprolactone. The filling process is investigated in situ with small angle x-ray scattering. The time-dependent scattering intensity is investigated with a model function based on the Lucas-Washburn equation for the filling process of liquids in cylindrical pores. The model function describes the data qualitatively well in terms of a t-dependency of the filling height, but deviates clearly from the expected quantitative values of the bulk material properties. Furthermore, the occurrence of a precursor film wetting the nanopore surface on a short time scale is observed.
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