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Latex Films (latex + film)
Selected AbstractsA New Method of Reproduction of Fingerprints from Corpses in a Bad State of Preservation Using LatexJOURNAL OF FORENSIC SCIENCES, Issue 6 2007Davide Porta B.Sc. Abstract:, In view of the problems arising while fingerprinting corpses in a bad state of preservation, especially in case of mummification and carbonization, the authors propose an innovative technique which uses latex film. To better illustrate the potential of the method, two cases where the latex technique was applied successfully are reported: the first one is a mummified body discovered in a shack on the outskirts of Milan and the second one is the case of a burnt corpse found in a car boot. Such a technique is versatile, easy to apply, and allows the operator to work quickly on cadavers without amputating parts, except in rare cases (i.e., burnt bodies with muscle retraction). By the latex technique, a perfect and enduring negative copy of the fingerprint is obtained, ready to be inked and photographed. The numerous copies produced this way can be inked several times allowing for the repeatability of the procedure and this is crucial in cases of problematic legal identification of corpses. In both the cases illustrated, the fingerprints obtained by the latex technique were useful for identification. The quality was good enough for the automatic fingerprint identification system research system to be applied. [source] Synthesis of an alkali-swellable emulsion and its effect on the rate of polymer diffusion in poly(vinyl acetate-butyl acrylate) latex filmsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Jung Kwon Oh Abstract We describe the synthesis and characterization of a weakly cross-linked poly(methacrylic acid- co -ethyl acrylate) alkali-swellable emulsion (ASE), as well as an investigation of its influence on the rate of polymer diffusion in latex films. The films examined were formed from poly(vinyl acetate- co -butyl acrylate) latex particles containing a small amount of acrylic acid as a comonomer. Polymer diffusion rates were monitored by the energy transfer technique. We found that the presence of the ASE component, either in the acid form or fully neutralized by ammonia or sodium hydroxide, had very little effect on the polymer diffusion rate. However, in the presence of 2 wt % NH4 -ASE, there was a small but significant increase in the polymer diffusion rate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5632,5642, 2005 [source] Epoxy-functionalized, low-glass-transition-temperature latex.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2002Abstract This article describes the results of experiments examining the competition between the polymer diffusion rate and the crosslinking rate in low-glass-transition-temperature, epoxy-containing latex films in the presence of a diamine. We examined films formed from donor- and acceptor-labeled poly(butyl acrylate- co -methyl methacrylate- co -glycidyl methacrylate) copolymer latex and studied the influence of several parameters on the growth rate of gel content and the rate of polymer diffusion. These factors include the molecular weight of the latex polymer, the presence or absence of a diamine crosslinking agent, and the cure protocol. The results were compared to the predictions of a recent theory of the competition between crosslinking and polymer diffusion across interfaces. In the initially formed films, polymer diffusion occurs more rapidly than the chemical reaction rate. Therefore, these films fall into the fast-diffusion category of this model. In our system (unlike in the model), the latex polymer has a broad distribution of molecular weights and a distribution of diffusivities. The shortest chains contribute to the early time diffusion that we measure. At later stages of our experiment, slower diffusing species contribute to the signal that we measure. The diffusion time decreases substantially, and we observe a crossover to a regime in which the chemical reaction dominates. The increases in chain branching and gel formation bring polymer diffusion to a halt. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4098,4116, 2002 [source] Interactions between aroma compounds and latex films: partition coefficients and influence on latex film formationPACKAGING TECHNOLOGY AND SCIENCE, Issue 2 2006A. Nestorson Abstract The potential of various latex grades to take up, retain and release different types of aroma compound has been explored. The latex grades used included two styrene,acrylate latices and two styrene,butadiene latices, of which one contained talc. The aroma compounds used were ethyl butyrate, 1-hexanol, heptanal, 3-octanone, ,-pinene and limonene dissolved in propylene glycol. It was shown that talc improves both the uptake of aroma compounds in the dispersion phase and the retention during the film formation process. However, the styrene,acrylate latex had a greater ability than the styrene,butadiene latex to hold the aroma compounds once the films were formed. These results have been compared to calculated solubility parameters. The uptake of 1-hexanol and propylene glycol in the latex dispersions were higher than expected from the theoretical calculations, probably because of the amphiphilic nature of these molecules. In addition, the influence of aroma compounds on the film formation was evaluated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Viscoelastic and damping characteristics of poly(n -butyl acrylate)-poly(n -butyl methacrylate) semi-IPN latex filmsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2007K. I. Suresh Abstract This article reports the synthesis, characterization, and damping characteristics of semi-interpenetrating (semi-IPN) latex systems composed of poly n -butyl acrylate (PBA) core and poly n -butyl methacrylate (PBMA) shell. The IPN's were prepared by seeded emulsion polymerization using crosslinked PBA seeds with varying crosslinker (m -diisopropenyl benzene) concentration. The polymer weight ratio in the first and second stage polymerization is maintained at 1:1 in all the cases. The particle size determined by dynamic light scattering shows a decrease in the shell thickness with increasing crosslinker concentration of the seed. The mechanical properties, like Shore A hardness of the films, increased from 18 to 65 when the crosslinker concentration is increased from 0 to 4.8,mol%. The dynamic mechanical studies show that the modulus value of the IPN's is below that of non-crosslinked films, and the value depends upon the crosslink density of the seed. Mechanical models, such as the Kerner's model and the Takayanagi's model, were used to explain the variation in the dynamic mechanical properties with the degree of seed crosslinking. The study indicates lower bound (rubbery) behavior for the films with lightly crosslinked cores. The study also shows that, at lower crosslinker concentration enhanced phase separation and better damping properties are achieved but at higher cross linker concentration (>2,mol%) greater interpenetration of the shell monomer to the cores takes place and tough films, with reduced damping properties are formed. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||