Kinetic studies and process analysis of the reactive compatibilization of nylon 6/polypropylene blends

This article describes a study on the reactive compatibilization of nylon 6 (N6) and polypropylene (PP) blends through a functionalized PP. A graft copolymer was formed in-situ by reacting an acid modified PP with N6 during blend compounding. The compatibilization reactions are studied in detail. Kinetics were estimated by means of experiments in a batch mixer. Three time constants were estimated, corresponding to (a) reactions, (b) melting of polymers, and (c) melt mixing. The effects of temperature and rotor speed on the reaction kinetics were also measured. There was a substantial increase in initial reaction rate, as the rotor speed was increased. Increasing the temperature did not significantly affect the reaction rate. Process parameters important for such a reactive compatibilization process were identified by statistically designed experiments in a co-roatating intermeshing twin-screw extruder. Screw speed, presence of venting, and sequence of feeding were shown to have a noticeable effect on the reactive compatibilization process during continuous compounding.     

Online political marketing in Greece: An evaluation of the 2007 national elections and two case studies

This paper presents findings on the use of Web sites as a political marketing tool in the context of the 2007 Greek national elections. The questions guiding this research are how popular were online campaigns in terms of candidate use of Web sites and which trust and credibility-building Web site design cues were leveraged by candidates. This study also explored differences in online campaign practices both between Greek political parties and between the 2007 national Greek elections and the 2002 federal US elections.     

Critical modeling parameters identified for 3D CFD modeling of rectangular final settling tanks for New York City wastewater treatment plants

New York City Environmental Protection is in the process of incorporating biological nitrogen removal (BNR) in its wastewater treatment plants (WWTPs) which entails operating the aeration tanks with higher levels of mixed liquor suspended solids (MLSS) than a conventional activated sludge process. The objective of this paper is to discuss two of the important parameters introduced in the 3D CFD model that has been developed by the City College of New York (CCNY) group: (a) the development of the 'discrete particle' measurement technique to carry out the fractionation of the solids in the final settling tank (FST) which has critical implications in the prediction of the effluent quality; and (b) the modification of the floc aggregation (K(A)) and floc break-up (K(B)) coefficients that are found in Parker's flocculation equation (Parker et al. 1970, 1971) used in the CFD model. The dependence of these parameters on the predictions of the CFD model will be illustrated with simulation results on one of the FSTs at the 26th Ward WWTP in Brooklyn, NY.     

Do websites influence the nature of voting intentions? The case of two national elections in Greece

This paper aims to contribute to the growing body of research on online political marketing by investigating the use of websites as a marketing tool in the 2007 and 2009 general elections in Greece. The two main research objectives are firstly to establish the key factors affecting voters’ trust when it comes to using politicians’ websites and secondly to examine whether and to what extent the influence of trust-building factors changes over-time, as the online environment matures. The key findings of this research are that users tend to visit the websites of favoured candidates, which reinforces their positive perceptions of them, while as far as the websites themselves and their content and the services provided are concerned there is still room for improvement.     

Numerical simulation of the wire‐pinning process in PET film casting: Steady‐state results

Poly(ethylene terephthalate) (PET) film casting involves melt flow through a slot die, across a small span, and onto a fast moving quench drum. In the “wire‐pinning” casting process, a thin electrified wire close to the line of contact with the drum creates a strong pinning force that delays air entrainment to higher line speeds. Nonuniform wetting of the die lips by the extruded melt is thought to be responsible for the formation of streaks, a defect in the machine direction. A finite element model of the film casting process with wire pinning was developed to assist in understanding what causes significant wetting of the lips and whether this can be avoided by electrostatic pinning. The solution of the governing equations provide the location of the static and dynamic contact lines, thus finding the wetting and pinning points in the process. The simulations investigate the sensitivity of the static wetting line locations on the die lands to the imposed values of static contact angle and die‐lip gap. It was found that while the contact angle has a small effect on the extent of die‐lip wetting within the parameter ranges examined, there is a considerable chance that the feed slot surfaces can be dewetted. This seems to be the greatest danger for causing streaks rather than excessive wetting of the die lands. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Extended survey of indoor and outdoor terrestrial gamma radiation in Greek urban areas by in situ gamma spectrometry with a portable Ge detector

The results obtained from more than 1000 indoor and outdoor in situ gamma spectrometry measurements in 41 towns (from all geographic subdivisions) of the Greek mainland (not islands) are presented. From the in situ gamma spectra the absorbed dose rate in air due to uranium series, thorium series, 40K and 137Cs are derived and discussed.