Liquid crystalline matrix polymers for aramid ballistic composites

Five semi‐flexible thermotropic liquid crystalline (LC) polyesters and poly(ester‐amide)s were synthesized and used as matrix resins for Twaron™ aramid‐based ballistic fabrics. The ballistic performance was investigated as a function of the neat resin content. For the most successful liquid crystalline polyester system, the effect of blending with styrene‐ethylene‐butylene‐styrene (SEBS) and polyvinyl butyrate (PVB) rubber was also explored. The best neat resin V50 values were obtained for 20 wt% LC polyester (LCPE)‐Twaron™ composites, that is, 418 m.s⁻¹, whereas SEBS/LCPE and PVB/LCPE modifications resulted in maximum V50 values of 460 and 466 m.s⁻¹, respectively. It was found that the ballistic impact resistance is strongly influenced by the elastic modulus of the resin component and to a lesser extent to the level of adhesion between the resin and fabric. The effect of resin content, resin strength, elongation‐at‐break, and resin toughness on the ballistic impact resistance was found to be small. The best ballistic protection could be obtained when the Young's modulus of the LC resin was in the range of 0.01–1 GPa. This result seems to be in agreement with existing inter‐yarn friction models. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Zeitliche Darstellung des Alterungsverhaltens eines Oxidationskatalysators in einem Biogas-BHKW

The emissions released during the burning of biogas are subject to legal limits. In order to comply with these limits, exhaust aftertreatment is required by oxidation catalyst. Over time, decreasing pollutant conversion occur due to aging of the catalyst. Therefore, after only 1.5 years working time, compliance with the formaldehyde limit is no longer possible with certainty. The main reason is the deposition of inorganic compounds called oil ashes. These flue gas components from biogas engines block the catalytic active species and plugs pores.     

Microbiological Environmental Monitoring After the Use of Air Purifier Ozone Generator

The work aimed to evaluate the indoor microbiological air quality after using the purifier ozone generator (Brizzamar®), by counting the total viable microorganisms. The plates containing the culture media were exposed on pre-defined locations for 10 min at the times 0 h (without purifier), 1, 2 and 3 h (with purifier). The results showed significant decreases in the microorganisms after using the purifier, reaching a reduction up to 80% of the fungi and bacteria in the environment after two hours. The amount of ozone in the atmosphere was kept at 0,01 ppm, which is considered non-toxic to human exposure. The purifier significantly improved the air quality in indoors.     

Automatic measurement of streamer chamber pictures

Streamer chamber pictures were measured with a flying spot device, which uses a CRT and is controlled by a PDP-7. It is possible to recognize each individual streamer along the track. Ionization measurements can be done automatically. These results are compared with hand measurements.     

Hyperbaric oxygenation in a large hyperbaric chamber (author's transl)

Hyperbaric Oxygenation has been used routinely with 503 persons (1100 compressions) in a large walk-in hyperbaric chamber. An optimal interdisciplinary teamwork and mastering of the transportation problems by helicopter is mandatory to make this treatment accessible for patients in distant hospitals as an additional conservative management. In 51 operations under pressure (28 congenital heart disease cases) the luxury oxygenation was a protective measure. The procedure can be done safely with plenty of working time.     

How mold inserts influence the replication of metallic microparts produced by electroplating into two-component templates

Multi-component injection molding combined with electroplating, the so-called MSG process, represents a promising process chain to replicate metallic microstructures. MSG is the German acronym of ‘Mehrkomponenten-Spritzgießen und Galvanoformung’, in English ‘Multi-component Injection Molding and Electroplating’. The process is based on the highly accurate reproduction of surface details through injection molding to build a microstructure into a two-component template and electrodeposition of e.g. nickel into this cavity. This electroplated micropart is the replication of the former structure. To study the influence of the mold insert on the accuracy of the molded part and the produced microparts, a test specimen was fabricated and analyzed using a milled mold insert. On the mold insert, three microcoil parts, the components of a microgripper, were micromilled. The effect of the individual process steps on the surface quality and dimensional changes of the final microcoil will be presented. It will also be shown how the quality of the injection molding insert influences the dimensional accuracy of the produced microparts. Finally, potential process improvements will be outlined.