Effect of nanofillers on the flame retardant properties of a polyethylene–calcium carbonate–silicone elastomer system

This study shows the effects of three different nanofillers on the viscosity properties and fire behavior of a halogen‐free flame retardant system. The original system, based on ethylene‐acrylate copolymer, calcium carbonate, and a silicone elastomer, shows good flame retardant properties. One of the nanofillers, montmorillonite (MMT), significantly increases the viscosity above 250^°C, resulting in reduced dripping and decreased heat release rate. The ash residue, however, is very brittle, indicating poor interactions between the MMT and other components of the system. The second nanofiller, sepiolite, shows no improvement on the flame retardant properties of the system. Reduced dripping is observed when a small amount of the third nanofiller, polyhedral oligomeric silsesquioxane, POSS, is incorporated into the system. In this case, high silica content on the surface indicates char formation originating from the POSS. However, an increased heat release is observed when POSS is used in the system. Copyright © 2010 John Wiley & Sons, Ltd.     

STRAINS OF YEAST LETHAL TO BREWERY YEASTS

Strains of yeast that are lethal to brewery ale and lager yeasts have been isolated from production-scale two-stage stirred continuous fermentors. These strains release a “killer” factor which is highly active in the pH range 3.8–4.2. When the level of infection reaches 2% the concentration of killer factor is sufficient to give a selective advantage in continuous fermentation, whereupon the proportion of killer yeasts rises and the brewery yeast is rapidly killed. The beer acquires a characteristic off-flavour which has been described as “herbal/phenolic”. Both flocculent and non-flocculent killer strains have been found and these show the characteristics of Saccharomyces cerevisiae but appear to ferment additional wort sugar(s), have an abormally small cell-size and are pleomorphic in mixed culture.