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The curing kinetics of a sequential dual-curing system based on an off-stoichiometric amine-epoxy formulation with intermediate latent reactivity has been analyzed. The first curing stage is an epoxy-amine polycondensation taking place at low temperatures, while the second curing stage is an anionic homopolymerization of the excess epoxy groups, taking place at high temperatures and catalyzed by a latent base. The different reactivity of both polymerization processes allows an excellent separation into well-defined curing stages each of which can be analyzed individually. The kinetics of the two curing stages have been analyzed by integral isoconversional procedures and model-fitting methods. Both methodologies successfully simulated each curing stage and also the global curing process, showing that it is possible to control the activation of both curing stages. Isoconversional integral analysis is a simple yet powerful method that can be used for the simulation of temperature-controlled curing programmes. Model-fitting analysis is more suitable for the flexible simulation of processing scenarios such as the curing of composites.

We investigate the critical behavior of a reaction-diffusion system exhibiting a continuous absorbing-state phase transition. The reaction-diffusion system strictly conserves the total density of particles, represented as a non-diffusive conserved field, and allows an infinite number of absorbing configurations. Numerical results show that it belongs to a wide universality class that also includes stochastic sandpile models. We derive microscopically the field theory representing this universality class., Comment: 13 pages, 1 eps figure, RevTex style

PdO·1.4H2O 1 prepared in our laboratories, as well as commercially available palladium oxides 2–4 have been found to act as efficient catalysts for the Suzuki–Miyaura reaction in ethanol/water mixture at room temperature in air. Thus, in the presence of 1 mol% catalyst, the reaction between different aryl bromides and arylboronic acids afforded a wide range of functionalized biphenyls in quantitative yield. Catalyst 1 has shown to be the most active for all couples of substrates, and it can be recovered and recycled several times without marked loss of activity. It has been demonstrated by means of suitable tests that the true catalyst is a soluble form of palladium originated by metal leaching from the metal oxide precursor. It is worth of note that the amount of catalyst both in the solution and in the isolated organic product is about 1 ppm.