Compatibilization of polymer blends from poly(styrene‐co‐acrylonitrile) and polycarbonate by oxazoline modification of poly(styrene‐co‐acrylonitrile) in the melt

A good way of achieving compatibility in polymer blends of poly(styrene‐co‐acrylonitrile) (S/AN) and bisphenol A polycarbonate (PC) is the chemical modification of S/AN in the melt. A catalyzed reaction of the nitrile groups with a substituted 2‐amino alcohol or 2‐amino phenol resulted in a conversion of nitrile groups of 55–75% in 60 min. The introduced heterocyclic structures were ethyl hydroxymethyl oxazoline (EHMOXA) and benzoxazole (BenzOXA), respectively. The use of dibutyltin oxide as a catalyst led to the highest efficiency. The modified polymer was characterized by Fourier transform infrared and NMR spectroscopy, elemental analysis, and reactions with organic acids and anhydrides. The modified S/AN showed good technical compatibility (single glass‐transition temperature) with PC in blends made from solution and from the melt. All blends were characterized with oscillating rheometry and differential scanning calorimetry. Rheological measurements showed that EHMOXA–S/AN reacted with PC and had crosslinked structures, whereas BenzOXA–S/AN showed compatibilization without any (crosslinking) reaction. The melt blends of BenzOXA–S/AN and PC showed a downward shift in the complex viscosity due to the influence of the BenzOXA group. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2322–2332, 2003     

Analysis of microbending of CuZn37 brass foils based on strain gradient hardening models

Microbending experiments of brass foils were conducted and demonstrated clear size effects, i.e., the normalized bending moment increased with the reduction of foil thickness. The experiments were modeled using the classical plasticity model and three strain-gradient plasticity models. A modified Nix-Gao model was proposed to consider the number of twins across the thickness direction in strain hardening. It was found that the proposed model could better predict the normalized bending moment for both fine-grain and coarse-grain foils and the proposed equation for material intrinsic length could better capture the physics of material deformation. Furthermore, micro-hardness distributions in the bending area were measured and obvious lower-hardness region was found in the middle layer of fine-grain foils instead of coarse-grain foils. This indicates that the modified Nix-Gao model and the assumption of fully plastic bending worked better for coarse-grain foils than for fine-grain foils.     

Ersatzneubau der Kajen im Marinestützpunkt Wilhelmshaven

Replacement construction of quays at the naval base in Wilhelmshaven At the naval base of Wilhelmshaven the quay walls and dolphins of a floating bridge system are being renewed. The existing quays show extensive damage and stability deficits. In particular, microbially induced corrosion (MIC) on the back of the old sheet piling lead to rust corrosion of the old sheet pile walls. Content of the report is the conceptual and structural implementation of the measure quay renewal that has been executed since the beginning of 2013. Special attention is paid to the security of the stock during the construction period, the selected corrosion protection measures as well as the requirements for the installation of combined sheet piling.     

Shape memory alloy based controllable multi-port microvalve

This paper describes an innovative miniature multi-port valve with a thin foil of shape memory alloy (SMA) as actuator for switching and dosing gaseous and liquid media. The normally closed (NC) microvalve has two structured SMA actuators that are switched independently of each other and either two inputs and one output or one input and two outputs. In addition to switching the media in the 3/4-way arrangement, it can also be used with a flow sensor in a closed loop control for dosing. Furthermore, the valve design is layer-based so that individual components can be manufactured according to given requirements or using different manufacturing technologies depending on the batch size. The SMA multi-port microvalve showed flow rates of about 2300 ml/min (nitrogen gas) and about 45 ml/min (water) for an applied pressure difference of 200 kPa and a heating current of about 400 mA. For flow regulation a closed loop control was realized and evaluated for a pressure difference of 100 kPa and a setpoint value of 900 ml/min.

     

Chemical modification of poly(styrene-co-acrylonitrile) with 2-aminoalcohols and 3-aminoalcohol

Nitrile groups of poly(styrene-co-acrylonitrile) (SAN) can be converted to 2-substituted Δ²-oxazoline using 2-aminoethanol. The formation of oxazoline in SAN can be significantly increased through addition of substituted aminoalcohols like 2-amino-2-ethylpropane-1,3-diol and 2-aminobutanol and through reaction with 3-aminopropanol using dibutyltin oxide as catalyst. Using this procedure, dihydro-4H-oxazine can be easily produced from 3-aminopropanol due to the lower ring tension in comparison with the five-membered oxazoline ring.     

Multi-objective optimization of actuator system design for laser micro adjustment

Complex design processes require a high level of expertise and are time consuming. By assisting the engineer with a computer aided design system the design process can be accelerated and be made more reliable. Actuator system design for laser micro adjustment is complex and its challenges may be a hindrance for the application of laser micro adjustment. To overcome this obstacle a computer aided design system was developed which utilizes a multi-objective optimization algorithm to automatically improve actuator design. In this paper, the system and its components are presented. A special focus will be upon the assessment functions which allow the efficient assessment of an actuator design. An application example will be given to demonstrate the functionality of the design system. The presented work was carried out within the research project 530/59-2 entitled “Algorithmen und Bewertungsmethoden zur Optimierung von Aktorsystemen für die Mikrosystemtechnik” funded by the German Research Foundation (DFG). The authors would also like to thank the Erlangen Graduate School in Advanced Optical Technologies (SAOT) for their support.     

Network Formation Under Cumulative Advantage: Evidence from The Cambridge High-Tech Cluster

When joining a social network, the already well-connected often make for especially attractive partners because they can facilitate links to other network members. However, the effect is potentially weakened by increasing redundancy of contacts with network size. We consider the trade-off between these two factors in a dataset of the Cambridge High-Tech Cluster and compare results with the county of Cambridgeshire as a whole. As expected, network effects are stronger in the former, but in both datasets, redundancy does not offset the benefits of reach in attracting new partners.     

: a toolset for creating customized interfaces for grid user communities

is a comprehensive set of tools for creating customized graphical user interfaces (GUIs). It draws from the concept of computing portals, which are here seen as interfaces to application-specific computing services for user communities. While was originally designed for the use in computational grids, it can be used in client/server environments as well.Compared to other GUI generators, is more versatile and more portable. It can be employed in many different application domains and on different target platforms. With , application experts (rather than computer scientists) are able to create their own individually tailored GUIs.     

Influence of Lignin Type on the Mechanical Properties of Lignin Based Compounds

Several types of sulfur‐free lignins were melt compounded in a Werner & Pfleiderer twin screw extruder (ZSK 25) together with polyamide 11 (PA11), a biodegradable polyester (Ecoflex®) and a biodegradable polyesteramide (BAK®). Sulfur‐free lignins, precipitated from black liquors of alkaline pulping of annual plants, like sisal and abaca, were compared to a sulfur‐free lignin (Alcell™) obtained by organosolv wood pulping. Lignin content and lignin type were varied systematically in order to examine stress/strain characteristics and impact behavior. Compounds with lignins from annual plants showed similar or better mechanical properties in comparison to compounds with Alcell™ lignin. A polyamid 11 compound containing 30 wt.‐% abaca lignin gave a Young's modulus of 1 890 MPa, compared to 1 420 MPa for PA11 and a 28% increase of yield stress. The morphology of the lignin compounds was investigated by means of environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM).