Foamed plastics additives

Polymer Composition. The piopeities of foamed plastics aie influenced both by the foam stmctuie and, to a gieatei extent, by the piopeities of the parent polymer. The polymer phase description must include the additives present in that phase as well. The condition or state of the polymer phase (orientation, crystallinity, previous thermal history), as well as its chemical composition, determines the properties of that phase. The polymer state and cell geometry are intimately related because they are determined by common forces exerted during the expansion and stabilization of the foam. 

Other. Because a foam consists of many small, trapped gas bubbles, it can be very effective as a thermal insulator. Usually soHd foams are used for insulation purposes, but there are some instances where Hquid foams also find uses for insulation (see Eoamed plastics Insulation, thermal). Eor example, it is possible to apply and remove the insulation simply by forming or coUapsing the foam, providing additional control of the insulation process. Another novel use that is being explored is the potential of absorbing much of the pressure produced by an explosion. The energy in the shock wave is first partially absorbed by breaking the bubbles into very small droplets, and then further absorbed as the droplets are evaporated (53). 

Foamed plastics (qv) were developed in Europe and the United States in the mid-to-late 1930s. In the mid-1940s, extmded foamed polystyrene (XEPS) was produced commercially, foUowed by polyurethanes and expanded (molded) polystyrene (EPS) which were manufactured from beads (1,2). In response to the requirement for more fire-resistant ceUular plastics, polyisocyanurate foams and modified urethanes containing additives were developed in the late 1960s urea—formaldehyde, phenoHc, and other foams were also used in Europe at this time. 

Extruded Rigid Foa.m. In addition to low temperature thermal insulation, foamed PSs are used for insulation against ambient temperatures in the form of perimeter insulation and insulation under floors and in walls and roofs. The upside-down roof system has been patented (256), in which foamed plastic such as Styrofoam (Dow) plastic foam is appHed above the tar-paper vapor seal, thereby protecting the tar paper from extreme thermal stresses that cause cracking. The foam is covered with gravel or some other wear-resistant topping (see Roofing materials). 

Cooling is most effectively accomplished with a tandem arrangement of two extmders, as shown in Figure 12, wherein the first extmder ensures complete dissolution of the blowing agent, and the second extmder is operated at slow speed for optimum cooling. Additional information on extmsion of foams is contained in Reference 28 (see Foamed plastics Insulation, thermal). 

Finally, oligomers in reactive processing to produce foamed plastics and elastomers for various industrial purposes. These materials have many of the valuable properties of conventional polymers, with the addition of low density and high heat, electrical, and sound insulation characteristics.23... 

Some of them (adhesives, coatings, foam plastics, and resins) use Mannich bases or their derivatives as structural components of the material, whereas all the listed branehes are concerned with the use of important additives (mainly antioxidants) or auxiliaries such as basic catalysts and accelerators. Specific functions are performed, for instance, by agents improving the adhesion of photopolymerizable paints and by accelerator-modified adhesion promoters for mbber-to-wirc adhesion." ... 

The properties of a foamed plastic depend on the properties of the base polymer and the geometry of the foam structure, often referred to as structural variables. The polymer phase description must include the additives present. 

Pokrovsky, V. M. et al. Plastic foams with additives. Stroitel nye materialy i konstruktsii 1978, No. 1, 22 (in Russian)... 

Oxo-l,3-dioxolan-4-yl methyl L CHj-O-C-CI 23385-72-0 0 v° Dec. UV curable acrylic resins Hydro gels Blowing agents for plastic foams Foods additives... 

In addition, two journals (in English) deal exclusively with plastic foams. These are the "Journal of Cellular Plastics" (Technomic Publishing Co.) and "Cellular Polymers" (RAPRA Technology Ltd.). A valuable source of information for foamed plastics has been the annual proceedings of various technical organizations such as the Society of the Plastics Industry (SPl) the German FSK and others. 

This is a bimonthly publication published by Technomic Publishing Co., Inc. at 851 New Holland Avenue, Box 3535, Lancaster, PA 17604. This journal has been published for 24 years and is a major source of information in foamed plastics technology, covering new developments and applications. In addition to articles on product applications and markets there is an index of foamed plastic patents from industrial nations and a section on industry news. 

The percentage of solids in the dispersion adhesives is 35-55%, in some cases as much as 70%, the rest is water, which after the adhesive application must either be completely evaporated (ventilation time) or diffuse into the joined parts (wood, textiles, concrete, foams, leather). The film formation temperature in types containing plasticizers and flexibilizing additives is lower than in types that are free of plasticizers. Additives, so-called high boilers (ethyl glycol, ethyl glycol acetate, ethylhexanol), are used to bring the film formation temperature down. 

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