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...

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.

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).

For the first time, the manufacturing of metal‐organic framework‐based monoliths using a two‐step process is reported. In a first experiment, the in situ synthesis of Cu3(BTC)2 (benzene tricarboxylate [BTC]) on cordierite monoliths was chosen to immobilize Cu3(BTC)2. As this approach turned out to be of major disadvantages, the manufacturing of Cu3(BTC)2 monolithic structures was chosen. The two‐step fabrication process included the manufacturing of a molding batch in a lab‐scale kneader followed by extrusion in a ram‐extruder. As additives, methyl hydroxyl propyl cellulose and methoxy functionalized siloxane ether were chosen. The resulting monolithic structures have a specific inner surface area of 370 m2/g and show a high mechanical stability of 320 N.

Silane‐grafted polyethylene materials are processed in conventional thermoplastic fabrication machines. The shaped articles are then crosslinked in water by the formation of Si‐O‐Si crosslinks. This paper represents studies on the crosslinking progress in different environments at various temperatures. Molecular orientation is shown to become permanent and mostly irrecoverable even at 150°C, in the silane‐grafted solid state crosslinked specimens (the crosslinking temperature in water is well below the polymer melting temperature). These frozen molecular orientations have a significant effect on the tensile properties of the crosslinked materials causing higher yield stresses and lower elongations at break. The thermal and tensile properties of some silane‐grafted crosslinked polyethylene samples and peroxide‐crosslinked materials are compared and analyzed.