CHARACTERIZATION OF EVA-BASED ADHESIVES CONTAINING DIFFERENT AMOUNTS OF ROSIN ESTER OR POLYTERPENE TACKIFIER

Different amounts (50-170 php--parts per hundred parts of EVA, 33-63 wt%) of two tackifiers (hydrogenated rosin ester, polyterpene resin) were added to an ethylene vinyl acetate (EVA) copolymer containing 28 wt% vinyl acetate. The EVA and the tackifier were characterized using infrared (IR) spectroscopy, DSC measurements, and stress-controlled plate-plate rheology. The properties and compatibility of the EVA-tackifier mixtures were studied using DSC, DMTA, and stress-controlled plate-plate rheology. Immediate adhesion was measured as a quantification of tack, and the T-peel strength of roughened styrene-butadiene rubber/EVA-tackifier adhesive joints was also obtained. The increase in the amount of tackifier noticeably changed the crystallinity of polyethylene blocks in the EVA, and the temperature at the cross-over between the curves of the storage and loss moduli as a function of the temperature was displaced to a lower value. Whereas the hydrogenated rosin ester was compatible with the amorphous ethylene vinyl acetate copolymer regions of the EVA (Tg value increased) reducing its crystallinity, the polyterpene resin was compatible with the polyethylene blocks of the EVA (T g value was not modified), increasing its crystallinity. Immediate adhesion of the EVA-tackifier mixtures was improved by adding both hydrogenated rosin ester and polyterpene tackifiers. On the other hand, there was an optimum tackifier content at which the maximum T-peel strength value was obtained.     

Puerta of Dreams

Inside, Puerta América is a hotchpotch, but the problem is lessened by using the arch-minimalist John Pawson to design the communal areas, creating a passive backdrop to the chaos of themes that inhabit the rooms on different floors. A few architecture critics have claimed that some of the more famous contributors have merely placed their signature style within a hotel context. Copyright © 2005 John Wiley & Sons, Ltd.     

Photographic Propaganda under Peronism, 1946–55: Selections from the Archivo General de la Nación Argentina

This article analyses a representative selection of photographs from the Archivo General de la Nación Argentina produced by an army of photographers who assiduously chronicled Eva and Juan Domingo Perón’s public engagements. These images were shrewdly informed by an array of popular forms (tango lyrics, the storylines of photo–romances, movies, and radio serials), and by a set of visual models borrowed from the nineteenth-century photography tradition, commercial photography studios of celebrities, Hollywood fashion codes, Soviet-related paradigms anchored in the legacy of the socialist and anarchist movements of early twentieth-century Argentina, and from royal and religious iconography. Through their careful staging before the camera, Perón and Eva amalgamated these visual traditions with their political content in order to reach and unify the multiple socio-political constituencies of Argentina at the time. The conventional aesthetic – in terms of view angles, lighting, and composition – of such images granted their movement a patina of legitimacy and the sense of an enduring legacy.     

Investing in the Ground: Reflections on Scarcity,Remediation and Obdurate Form

Douglas Spencer develops David Harvey's notion of the ‘spatial fix’ in which material processes in the built environment and the ground itself are repeatedly used up for the purposes of capital investment. This can be to the detriment of the quality of the land itself, which is often abandoned after a period of time as polluted and unusable brownfield sites; while available resources are bled dry. It is a situation that has been worsened over the last few decades with the emphasis on entrepreneurial and intensive modes of urbanisation. Spencer indicates how this situation can be negated by landscape urbanism through critical interventions, such as those represented here in the work of the Architectural Association Landscape Urbanism (AALU) Masters programme in London and Groundlab, the practice associated with it.     

SURFACE MODIFICATIONS ON EVA TREATED WITH SULPHURIC ACID

In this study, treatment with sulphuric acid was used to increase the adhesion of an ethylene-vinyl acetate copolymer containing 20 wt% vinyl acetate (EVA20). The treatment with sulphuric acid improved the wettability of EVA20 due to thecreation of different oxygen and sulphonic acid moieties on the surface. The treatment also created cracks and heterogeneities on the EVA20 surface, and enhanced T-peel strength values of EVA20/polychloroprene adhesive+5 wt% isocyanate joints were obtained. The loci of failure of the joints were mixed, i.e. , adhesional and cohesive in the adhesive. Peel strength values of both as-received and sulphuric acid-treated EVA20/polychloroprene adhesive joints increased after ageing at 50°C and 95 wt% relative humidity for 72 because the complete cure of the adhesive was thereby was produced. The durability of the EVA20 treated with sulphuric acid was monitored between 15 min and 5 years. High peel strength values were obtained for times up to 61 days; the joints produced with the treated EVA20 five years after treatment showed lower peel strength value due to the creation of a weak boundary layer produced by reaction of the residual sulphuric acid on the surface with EVA20. On the other hand, different experimental variables in the treatment of EVA20 with sulphuric acid were considered. The optimum treatment conditions for EVA20 were obtained by immersion in highly concentrated sulphuric acid (96 wt%) for one minute followed by neutralisation with ammonium hydroxide.     

On the Outskirts of Physics: Eva von Bahr as an Outsider Within in Early 20th Century Swedish Experimental Physics

Abstract.   Eva von Bahr (1874–1962) got her doctorate in experimental physics at the Physics Institute at Uppsala University in 1908. Subsequently she became the first woman assistant professor in physics in Sweden. In the face of many obstacles, she worked as a physicist for six years in Uppsala and Berlin. In 1914 she took a position as a school teacher. This article explores von Bahr's trajectory through academic experimental physics. It is argued that network connections with male scientists enabled her work. Her associations were a mix between institutional relationships and informal connections, resulting in what is labeled a 'hybrid of connections'. Furthermore it is argued that von Bahr became an 'outsider within' in academic experimental physics. Her connections created openings, but these coexisted with hindrances. It is argued that von Bahr oscillated between being an insider and an outsider which created a fractured identity. Her position and identity was a mix between membership and non-membership. Through examining von Bahr's career this article aims to bring together historical research on women in science and theoretical work in science studies. Furthermore, the article argues the analytical value of feminist perspectives on scientific collaborations as a way to a deeper understanding of the network structures of science.     

Surface modifications on eva treated with sulphuric acid

In this study, treatment with sulphuric acid was used to increase the adhesion of an ethylene-vinyl acetate copolymer containing 20 wt% vinyl acetate (EVA20). The treatment with sulphuric acid improved the wettability of EVA20 due to thecreation of different oxygen and sulphonic acid moieties on the surface. The treatment also created cracks and heterogeneities on the EVA20 surface, and enhanced T-peel strength values of EVA20/polychloroprene adhesive+5 wt% isocyanate joints were obtained. The loci of failure of the joints were mixed, i.e. , adhesional and cohesive in the adhesive. Peel strength values of both as-received and sulphuric acid-treated EVA20/polychloroprene adhesive joints increased after ageing at 50°C and 95 wt% relative humidity for 72 because the complete cure of the adhesive was thereby was produced. The durability of the EVA20 treated with sulphuric acid was monitored between 15 min and 5 years. High peel strength values were obtained for times up to 61 days; the joints produced with the treated EVA20 five years after treatment showed lower peel strength value due to the creation of a weak boundary layer produced by reaction of the residual sulphuric acid on the surface with EVA20. On the other hand, different experimental variables in the treatment of EVA20 with sulphuric acid were considered. The optimum treatment conditions for EVA20 were obtained by immersion in highly concentrated sulphuric acid (96 wt%) for one minute followed by neutralisation with ammonium hydroxide.     

Parallel Indexing: Infrastructure and Space

As governments around the world open the public coffers in an attempt to pull their economies back from collapse, Holger Kehne and Jeff Turko describe how they have extended the work of the Architectural Association Diploma Unit 12 to incorporate the pertinent subject of infrastructure and architecture, employing ‘indexical systems’. Copyright © 2009 John Wiley & Sons, Ltd.