Institutfuer K u n s t s t o~c~2 o g i eUnwersitaet Stuttgart 70199 Stuttgart, G e m y Poly(1actide) (PLA). a biodegradable aliphatic polyester with excellent property profiles for different polymer applications, will play a major role in future markets for biodegradable polymers from renewable resources. PLA is a very brittle and stiff polymer with a glass transition temperature of around 58°C. The mechanical properties of PLA are comparable to those of polystyrene, with an elasticity modulus of 3500 MPa, a maximum tensile strength of 50 MPa. and an elongation at break of 4%. To introduce PLA into other applications requiring other mechanical property profiles, especially higher flexibility and higher impact resistance, it is necessary to use plasticizers. In this study the influence of several biocompatible plasticizer systems on the mechanical properties of PLA is determined. Poly(ethy1ene glycol), glucosemonoesters and partial fatty acid esters are introduced at 2.5, 5, and 10 wt?h into polylactide. The mechanical properties, such as impact strength and the stress-strain-interrelationship of tensile tests, show changes, which are discussed. IlllTRODUCTION liphatic polyesters represent an important familyA of biodegradable polymers (1-4) that can be produced from renewable resources. Polylactide (PLA) is the best known polymer of this family and has become of economic interest since recent advances have been achieved in the production of lactide from lactic acid as well as in catalyst development for ring-opening polymerization in bulk to form PLA. In particular, polylactide and copolymers of polylactide with other aliphatic polyesters have been widely examined for their use in biomedical applications (5-9).For several years applications of biodegradable polymers in commodity areas such as packaging and f i l m wrap (1 0) have been closely investigated. Recent advances in polymerization technologies (11-13) mean that the previously expensive PLA-polymers now have a good chance of being introduced in such low-priced packagmg applications.The mechanical properties of polylactides (PLA) are of great interest (14). Attempts have been made to improve the mechanid properties, either by chain orientation, by blending with other biodegradable polymers such as poly-e-caprolactone (PCL), or by using the formation of copolymers of PLA and PCL or other polyesters (15)(16)(17)(18)(19)(20)(21)(22). Indeed, it is known that by the copolymerization of PLA with other monomers, a huge range of mechanical properties can be achieved, but none of these copolymerization processes is yet economically viable and none is known to produce polymers on an industriaJ scale for packaging applications. As polylactide, similar to polystyrene, is a comparatively brittle and stif€ polymer with low deformation at break, one main task is to modify these properties in such a way that PLA is able to compete with other more flexible commodity polymers such as polyethylene, polypropylene, PET. or PVC. One interesting possibility is to alter the mech...

The electromagnetic interaction between Io and the Jovian magnetosphere generates a UV auroral footprint in both Jovian hemispheres. Multiple spots were observed in the northern Jovian hemisphere when Io was in the northern part of the plasma torus and vice‐versa for the South. Based on recent Hubble Space Telescope (HST) measurements, we report here the discovery of a UV leading spot, i.e., a faint emission located ahead of the main spot. The leading spot emerges at System III longitudes between 0° and 100° in the northern hemisphere and between 130° and 300° in the southern hemisphere, i.e., in one hemisphere when multiple spots are observed in the other hemisphere. We propose as one potential mechanism that electron beams observed near Io are related to the generation of the leading spot and the secondary spot in the opposite hemisphere.

Institutfuer KunststoflechnoZogie Universitaet S w a r t s w a r t , Germany +Centerfor Education and Research on Macromolecules University of Liege Liege, BelgiumPoly(1actide) (PLA), a biodegradable aliphatic polyester with excellent properties for different polymer applications, has been used mostly in the biomedical field, m a d y because of its high price, resulting from expensive polymerization and purification techniques. Although this polymer can play a major role in future markets for biodegradable polymers, the current high price has to be reduced significantly to at least $4 US/kg. Therefore, this paper aims to partially review the polymerization techniques traditionally used in PIA synthesis and to propose new developments that enable us to produce these polymers by an innovative process for just a portion of the costs traditionally charged, using reactive extrusion techniques in a closely intermeshing co-rotating twin screw extruder. This paper gives an overview of attainable mechanical properties and future markets.

[1] Io's relative motion in the plasma torus strongly perturbs the incident magnetoplasma. The waves generated by Io then propagate through the dense plasma torus, the low-density magnetospheric plasma and finally reach the Jovian ionosphere producing the well-known Io footprint. Direct spacecraft observations by the Voyager and Galileo spacecraft demonstrated that Io's interaction is nearly fully saturated, i.e. the plasma flow close to Io is nearly brought to a halt in conjunction with a strong magnetic field perturbation. Here we use a nonlinear, three-dimensional, time-dependent MHD model to examine how the Iogenerated waves propagate, are partly reflected at plasma density gradients, and nonlinearly interact. In this work, we concentrate on the basic properties of the wave propagation based on a simplified magnetic field geometry. Despite the idealization, structural features such as the shape and morphology of the Io footprint and its wake can be qualitatively compared to measured data. We show that a strong and saturated interaction fundamentally modifies Io's wave field from the linear wave morphology picture traditionally studied. In particular, we find that due to the strong and thus nonlinear interaction the standard law of reflection completely breaks down. Io's Alfvén waves are reflected in Jupiter's ionosphere nearly anti-parallel to the incident wave. We also notice overlapping and blending together of the multiply reflected Alfvén wings with increasing strength of Io's interaction. This could be a possible explanation for the disappearance of multiple footprints when Io moves to the torus center. Citation: Jacobsen, S., F.M. Neubauer, J. Saur, and N. Schilling (2007), Io's nonlinear MHDwave field in the heterogeneous Jovian magnetosphere, Geophys.

Although there are substantial differences between the magnetospheres of Jupiter and Saturn, it has been suggested that cryovolcanic activity at Enceladus could lead to electrodynamic coupling between Enceladus and Saturn like that which links Jupiter with Io, Europa and Ganymede. Powerful field-aligned electron beams associated with the Io-Jupiter coupling, for example, create an auroral footprint in Jupiter's ionosphere. Auroral ultraviolet emission associated with Enceladus-Saturn coupling is anticipated to be just a few tenths of a kilorayleigh (ref. 12), about an order of magnitude dimmer than Io's footprint and below the observable threshold, consistent with its non-detection. Here we report the detection of magnetic-field-aligned ion and electron beams (offset several moon radii downstream from Enceladus) with sufficient power to stimulate detectable aurora, and the subsequent discovery of Enceladus-associated aurora in a few per cent of the scans of the moon's footprint. The footprint varies in emission magnitude more than can plausibly be explained by changes in magnetospheric parameters--and as such is probably indicative of variable plume activity.

Poly(lactic‐acid) (PLA), a biodegradable polyester with excellent properties for different polymer applications, will play a major role in future markets for biodegradable polymers. But only if the currently very high price level can be reduced significantly to at least 4 $US/kg. Therefore, studies to fill poly(lactic acid) (PLA) with relative inexpensive native corn starch were conducted. Because PLA is a very brittle material with a glass transition point at 54°C, filling of PLA with native starch might seem unrealistic, as the brittleness is increased by the dispersed starch granules. To avoid this, low molecular weight poly(ethylene glycol) (PEG) is introduced into the PLA to enhance crystallization and to lower the glass transition temperature significantly under possible usage temperatures. The polymer that is modified in this way is then filled with native starch. The thermal behavior of the achieved di‐ or triblends is determined by means of differential scanning calorimetry (DSC) and the degradation behavior at high temperature has been looked at with the help of thermogravimetric analysis (TGA).

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International audienceThe Io footprint (IFP) is a set of auroral spots and an extended tail resulting from the strong interaction between Io and the Jovian magnetosphere. For the first time, we present measurements of the brightness and precipitated power for each individual spot, using the image database gathered from 1997 to 2009 with the Hubble Space Telescope in the Far-UV domain. We show that the relative brightness of the spots varies with the System III longitude of Io. Moreover, our novel measurement method based on 3D simulations of the auroral features allows to derive the precipitated energy fluxes from images on which the emission region is observed at a slant angle. Peak values as high as 2 W/m2 are observed for the main spot, probably triggering a localized and sudden heating of the atmosphere. Additionally, strong brightness differences are observed from one hemisphere to another. This result indicates that the location of Io in the plasma torus is not the only parameter to control the brightness, but that the magnetic field asymmetries also play a key role. Finally, we present new data confirming that significant variations of the spots' brightness on timescales of 2-4 minutes are ubiquitous, which suggests a relationship with intermittent double layers close to Jovian surface