Magnetic actuation principles using superparamagnetic beads suspended in a fluid are studied in this paper. An experimental setup containing a submicroliter fluid volume surrounded by four miniaturized electromagnets was designed and fabricated. On the basis of optical velocity measurements, the induced behavior of single beads and ordered chains was analyzed and compared to a theoretical model. This research can be used to develop new techniques for accelerated transportation in lab-on-a-chip bio-assays.

The specific volume change of Bisphenol A polycarbonate was measured at room temperature for several years. The effects of formation conditions like cooling rate and pressure, the addition of low molecular additives, and injection molding and quenching were investigated. The volume shrinkage at long times was found to be much higher than extrapolated from short term measurements. A general pattern is observed in the volume recovery curves. They start with a small constant slope on the logarithmic time scale. After about 107 s a transition is observed to a much steeper slope. Whereas in the first section the characteristic increase in τeff is observed, the volume recovery during the transition can be fitted quite well with a single exponential. The sharp transition suggests that there is a long retardation time, which may represent the genuine α-relaxation. It also means that the self-retardation during physical aging is finite. The slope at long times (>107 s) scales with the distance from equilibrium, as extrapolated from measurements close to T g. The cooling rate during vitrification affects the slope in the first zone only, while the formation pressure leads to a vertical shift of the curves. Addition of low molecular weight additives leads to a dramatic densification and accelerates the volume recovery.

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A multiflux static mixer can be used to produce multilayered structures. The flow is repeatedly cut, stretched and stacked by mixing elements in the channel of such a device. In the standard design, however, the obtained layer thicknesses are inhomogeneous. The causes for the multiflux static mixer's deviation from ideal behavior are identified by 3D numeical simulations as unequal pressure drops in the separating flows. Changes in the arrangements of the elements are proposed and their effects are verified by simulations and experiments. A significant improvement of the layer homogeneity is achieved by introducing additional elements with separatings walls at the inlets and at the outlets of the mixing elements.

Physical properties relating to chain stiffness are determined for a series of copolycarbonates of Bisphenol A and 1,1′-spiro[bis(3,3′-dimethyl-6-hydroxyindan)] (SBI) of varying composition. The entanglement molecular weight, Me, is derived from the rubbery plateau modulus. The recoverable compliance, J e 0 , is determined from the dynamic moduli as well as from steady shear creep and recovery experiments. It is found that all properties change in a nonlinear fashion with SBI content. For small SBI content the entanglement density is hardly affected, whereas Tg and J e 0 increase strongly. With further increase in SBI content the effect on Tg is less pronounced. Me, however, starts increasing progressively to about 10 times that of pure Bisphenol A polycarbonate. The functional dependence of Me on composition is not predicted correctly from group contributions.

The birefringence distributions in injection‐molded Compact Discs (CD) are determined in radial and tangential cross‐sections and interpreted in terms of the process. The influence of processing conditions is discussed in several examples. It is shown that despite the high birefringence level the retardation of a beam of normal incidence is almost zero due to several compensation mechanisms. One optical axis is almost perpendicular to the surface. The medium, however, is biaxial with the preferential directions depending on the distance from the surface and the radial position. In contrast to a parallel beam, zero retardation cannot be achieved with a convergent beam in injection‐molded polycarbonate disks for that reason.

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