Surface blooming

OM Identification of compounding ingredients, particle size, dispersion, surface blooming, image analysis... 

To get proper rubber to fabric adhesion the fabric must be quite dry and evenly coated with the adhesive and adequately dried up. Defective adhesion occurs due to contamination by surface blooming of ingredients. Sulphur blooms can be eliminated by the use of insoluble sulphur. Waxy softeners which bloom at the surface should be avoided in compounding formulations. 

Because antiozonants and waxes, which to be effective must form a surface bloom, are used to enhance ozone resistance it is usual to condition test pieces in the strained state before exposure. The usual conditioning period is between 48 and 96h and the test pieces should be kept in the dark and in an ozone-free atmosphere. For this treatment to be effective, the test piece surface must not of course be touched in the course of subsequent handling. Where specifications wish to specifically exclude compounds which rely on an adequate wax film for protection, the conditioning period is dispensed with. Hill and Jowett47 in a criticism of ozone test methods strongly make the point that the conditioning process should be relevant to service conditions if a discriminating evaluation of waxes is to be made. 

Lonchampt, P. and Hartel, R.W. (2006). Surface bloom on improperly tempered ehoeolate. European Journal of Lipid Science and Technology, 108(2) 159-168. 

Summer Bloom The buoyant surface blooms of diazotrophic cyanobacteria (Nodularia spumigena. Aphanizomenon sp., Anabaena spp.) are the most impressive bloom phenomena in the Baltic Proper. Nodularia blooms are also of socioeconomic interest because they are potentially toxic (Wasmund, 2002). As diazotrophic cyanobacteria are not... 

H.W. Paerl, J. Tucker, P. T. Bland (1983). Carotenoid enhancement and its role in maintaining blue-green algal Microcystis aeruginosa) surface blooms. Limnol. Oceanogr., 28, 847-857. 

The first alcoholic wines were most likely an accidental discovery from fermented grapes. Most fruits are contaminated with microbes that form the surface bloom, which results in a natural alcoholic fermentation when given the right climatic environment. Earliest references to the production of distilled spirits appear to have origi-... 

Both yellowing and embrittlement of polypropylene are dose dependent but are significant at or around 25 kGy (the customary compendial dose for sterilizing medical devices). The extent of radiation-induced discoloration can be relieved by use of phosphite stabilizers. Stability against embrittlement may be improved by adding antioxidants, but these may in turn create problems such as surface blooms. ... 

One main characteristic of bloom forming freshwater cyanobacteria is their ability to regulate buoyancy with the aid of gas vesicles and thus to avoid light limitation in turbid waters. This provides a clear competitive advantage over other phytoplankton that may sediment when the water column is stable during periods of thermal stratification. Buoyancy due to gas vesicles frequently induces the formation of surface blooms, so-called scums, thus causing a high variability in spatial distribution of cyanobacteria. ... 

All toxigenic taxa have been reported to form surface blooms that can be displaced by wind action to the downwind side of lakes. As a result, MC concentrations can vary considerably at different sampling sites. In the example shown in Figure 39.6, MC concentrations at central sites are... 

Physical Antiozonants. Saturated waxes are added during rubber compounding. Being immiscible, they migrate to the surface (bloom), forming a barrier coating that... 

Figure 5.3 Surface bloom of sulphur cured natural rubber Reprinted from A. D. Roberts, Wear, 1997, 42, 119, Figure 7, with permission...

The biocide must be both physically and chemically compatible with the polymer formulation. Most biocides work only at the surface of the plastic. For the biocide to be effective, it should be able to distribute within the plastic. The biocide must have sufficient solubility in the polymer matrix so that it can diffuse within the polymer to come to the surface, but not bloom at the surface. Blooming will result in premature loss of biological activity and possibly give rise to unacceptable risk of human and environmental exposure at the surface of the plastic article. Biocides that are chemically incompatible with the additives in the polymer can result in discoloration. In addition, chemical reactions between the biocide and some formulation ingredients can result in deactivation of the biocide. 

The diene ethylidiene norbornene in Vistalon EPDM allows sulfur vulcanization (see Table 3.12). 1,4-Hexadiene and dicyclopentadiene (DCPD) are also used as curing agents.The completely saturated polymer backbone precludes the need for antioxidants that can bleed to the surface (bloom) of the finished product and cause staining. Saturation provides inherent ozone and weather resistance, good thermal properties, and a low compression set. Saturation also allows a relatively high-volume addition of low-cost fillers and oils in compounds while retaining a high level of mechanical properties. The ethylene/propylene monomer ratio also affects the properties. 

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