Rheology for processing

The core competence of the Materials Technology group (MATE) is formed by the triangle of numericalmethods, constitutive equations and experimental methods. The ultimate goal of the group is to bridgethe gap between science and technology in the area of materials processing and design, via the useof computational tools in the modelling of the full thermo-mechanical history of material (elements)during their formation, processing and nal design, in order to be able to quantitatively predict productproperties.This approach will be demonstrated with some illustrative examples of research projects. The rstexample is the (extended) POMPOM model for describing viscoelastic ows of polymer melts. Thisnew model shows excellent predictive capability and is considered to be a break through in the area ofviscoelastic modelling. The results of viscoelstic modelling are an important part of other issues like owinstabilities (example 2) and ow induced crystalization of semi-crystaline polymers (example 3). Thelast two examples are applied to injection moulding. Finally, the modeliing of mixing is dealed elds. A new tool, the so-calledmapping method, is demonstrated, This method allows, for the rst time, optimization of highly viscousmixing processes with a constant rheology

Flow-induced crystallization and resulting anisotropic properties

It is well known that flow gradients can have a major influence on the crystallization of semi-crystalline polymers. Not only the nucleation rate can change dramatically, but also the type of nuclei can change depending on the level of orientation of the molecules; especially the orientation the high molecular weight fraction. The level of modeling of flow induced crystallization (FIC) has improved quite a lot the last few years. Even the influence of hard particles on the local stress level and the FIC behavior is now studied numerically. These models reveal the importance of the coupling between rheology and FIC. Having available reliable parameters values that enter these models is becoming more urgent and so is the need for reliable and accessible experiments that combine rheological characterization methods with structure characterization methods. We use shear and extensional flow combined with different structure characterization methods such as microscopy, TEM and SEM, SALS, FIB and WAXS/SAXS on both linear and a branched polymers. The evolution of the detailed structural information, including crystallinity, lamellae thickness, long spacing, spherulite size and orientation, is linked to the evolution of the rheological parameters and providing, in this way, the input for the models. Next, we link this structural information to mechanical properties, in particular the impact strength.A full multi scale approach is used that allows for taking into account anisotropy at different levels and the influence of both soft and hard particles

Mechanical modeling of skin

\u3cp\u3eThe chapter describes the work that was performed in the soft tissue biomechanics laboratory at Eindhoven University of Technology on the biomechanics of skin. A rationale is given for the changes from standard testing methods to inverse methods, from in vitro to in vivo and back to in vitro testing and for the more detailed studies on individual skin layers of the last decade. The chapter tries to explain how our vision on testing methods and modeling changed over the years and why the pursuit towards a complete constitutive model is still ongoing.\u3c/p\u3

Mandrel for making stented or stentless heart valve comprising a fibre reinforced composite material

he mandrel comprises a cylindrical lower mandrel half-section with at least three sloping surfaces at its top end, and a cylindrical upper mandrel half-section containing a cavity with sloping side walls in its bottom end, the angles of these side walls corresponding to the angles of the sloping surfaces at the top end of the lower mandrel half-section. The bottom end of the upper mandrel half-section is provided with protuberances extending in the circumferential direction, the number and positions of which correspond to the cavity side walls. A mandrel used for making a synthetic, fibre-reinforced heart valve comprises an essentially cylindrical lower mandrel half-section with at least three sloping surfaces at its top end, and an essentially cylindrical upper mandrel half-section containing a cavity with sloping side walls in its bottom end, the angles of these side walls corresponding to the angles of the sloping surfaces at the top end of the lower mandrel half-section. The bottom end of the upper mandrel half-section is provided with protuberances extending in the circumferential direction, the number and positions of which correspond to the cavity side walls. Independent claims are also included for (a) two methods for making a synthetic, fibre-reinforced stentless heart valve using this mandrel, (b) a method for making a synthetic, fibre-reinforced stented heart valve using this mandrel, and (c) a synthetic, fibre-reinforced stentless heart valve comprising an essentially cylindrical tube with outwards protruding parts and leaflets on the inner wall, the leaflets containing reinforcing fibres (42) that extend into the tube material

Drug delivery devices: recent devolpments and expectations

This study, forming part of the Public Health Status and Forecast 2002, produced by the National Institute of Public Health and the Environment in the Netherlands, describes the state of the art on drug delivery devices, as well as future developments for their use. It is concluded that many examples of new or improved drug delivery devices have improved drug therapy and patient convenience in the last decade. Still, besides the development of new active compounds, the improvement of drug delivery devices is a key factor in the future development of drug therapy. In drug therapy, administration as well as formulation of substances is difficult. A drug delivery device is required to stabilise the characteristics of these compounds. For example, the application of gene therapy is still hampered by the lack of adequate ways of administration. New drug delivery devices with colloidal carriers (for example liposomes or polymers) are expected to play an important role in the treatment of life threatening, frequently occurring or difficult to cure diseases. In the future macromolecular and other complex compounds will become more and more important. Consequently, the technology that facilitates the administration of these substances has to improve accordingly.Een overzicht van de stand van zaken en toekomstige ontwikkelingen met betrekking tot veel voorkomende toedieningsvormen en -systemen wordt in dit rapport van het Rijksinstituut voor Volksgezondheid en Milieu beschreven, als achtergrondstudie van de Volksgezondheid Toekomst Verkenning 2002. Een geneesmiddeltoedieningsvorm of -systeem is vrijwel altijd noodzakelijk omdat de werkzame stof niet zomaar aan de pati6nt kan worden toegediend. Vele voorbeelden van nieuwe en veranderde toedieningsvormen hebben in de afgelopen decennia het licht gezien, en hebben bijgedragen aan een veranderende therapie. Veelal betekent dit een vergroting van het gebruiksgemak voor de pati6nt. Toch blijft er nog een grote behoefte aan verdere ontwikkeling van toedienings-vormen en -systemen omdat ze, naast nieuwe werkzame stoffen, essentieel zijn in de verdere verbetering van de therapie voor veel ziekten. Nieuwere toedieningsvormen met collo6dale dragers (zoals liposomen en polymeren) zullen een belangrijkere rol gaan spelen in de behandeling van levensbedreigende, veel voorkomende, of nog niet of moeilijk te behandelen ziekten. Naast deze geheel nieuwe ontwikkelingen zal ook de zoektocht naar methodes om bestaande stoffen veiliger en effectiever toe te dienen zich blijven voortzetten. In de toekomst zullen er namelijk steeds meer macromoleculaire en complexe verbindingen als werkzame stof worden toegediend. Niet alleen qua toediening maar ook qua formulering zijn dit veelal lastige verbindingen. Een toedieningsvorm is dan noodzakelijk om de eigenschappen van deze werkzame stoffen onder verschillende omstandigheden (produktie, opslag, toediening aan het lichaam) constant te houden. Dat toedieningsvormen een belangrijke rol kunnen spelen speelt bijvoorbeeld bij gentherapie een rol: deze toepassing wordt vertraagd door toedieningsproblemen