Prediction of mechanical properties of compatibilized styrene/natural‐rubber blend by using reaction conditions: Central composite design vs. artificial neural networks

A polystyrene (PS)/rubber blend compatibilized with PS‐g‐rubber copolymer, prepared via emulsion polymerization using redox initiator system, is used to investigate the utilization of central composite design (CCD) and artificial neural network (ANN) approaches in correlating polymerization conditions to mechanical properties (tensile strength and abrasion loss) of unfilled compound vulcanizates. The conditions were manipulated by changing four factors: reaction temperature and time, percentage of deproteinized rubber in the mixture containing natural rubber, and amount of chain transfer agent. The results show that the relationships between the conditions and the mechanical properties for compatibilized PS/rubber blend are too complex to be explained by polynomials, but are well described by the ANN models, developed for each response. In addition, simulation results for the tensile strength response as a function of those factors using the obtained ANN are in agreement with literature, whereas those results for the abrasion loss do not quite agree with literature due to the interference of the large measurement error. This suggests that only experimental data with high precision should be used to train an ANN to achieve a model with not only best performance but also high reliability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci. 2013     

Improvement of proton-exchange membrane fuel cell performance using platinum-loaded carbon black entrapped in crosslinked chitosan

To improve the performance of proton-exchange membrane fuel cells which use hydrogen and oxygen as fuels, the application of small proton-conducting polymer to extend the three-phase boundary into the primary pores of catalyst-loaded carbon black agglomerates is of interest. An alternative and simple crosslinking method is proposed in place of the complicated polymer-grafting methods. Platinum-loaded carbon black is entrapped in epichlorohydrin-crosslinked chitosan of low molecular weight. Morphology and pore analyses of carbon black prior and post treatment are assessed, as well as performances of fuel cells fabricated with the treated and the untreated carbon black at 40 °C and 100% humidity. Results indicate the existence of chitosan chains in the primary pores of the carbon black agglomerates, corresponding to a decline in the activation overvoltage and resulting in significantly better cell performance. An increase in chitosan amount, however, does not necessarily enhance the cell performance because effects of ohmic and concentration losses may become more dominant than that of the raised exchange current density of the cell.     

A simple postsulfonation of poly(arylene ether sulfone) Radel® R

Commercially available Radel® R, a poorly acid resistant biphenol‐based poly(arylene ether sulfone), was successfully sulfonated by a simple and rapid postsulfonation reaction using oleum as the sulfonating agent. Polymer degradation due to contact with acid could easily be minimized by adjusting reaction conditions. The suitable reaction conditions, when the 1 : 3 molar ratio of the polymer to the sulfonating agent was used, were: 10% of oleum in chloroform, 10% concentration of Radel® R in chloroform, and temperature between 0 and 50°C. Under these conditions, the reaction was complete within 45 min. Thermal properties, degradation characteristics and the viscosity of the postsulfonated polymer are reported. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011