Polymers foaming agents

GRO Grolier, J.-P.E. and Randzio, S.L., Simple gases to replace non-environmentally friendly polymer foaming agents. A thermodynamic investigation, J. Chem. Thermodyn., 46, 42, 2012. 

Many different types of foaming agents are used, but nonionic surfactants are the most common, eg, ethoxylated fatty alcohols, fatty acid alkanolamides, fatty amine oxides, nonylphenol ethoxylates, and octylphenol ethoxylates, to name a few (see Alkylphenols). Anionic surfactants can be used, but with caution, due to potential complexing with cationic polymers commonly used in mousses. 

Other minor uses of ethyl chloride iaclude blowiag agents for thermoplastic foam (51) and styrene polymer foam (52), the manufacture of polymeric ketones used as lube oil detergents (53), the manufacture of acetaldehyde (qv) (54), as an aerosol propellent (55), as a refrigerant (R-160), ia the preparation of acid dyes (56), and as a local or general anesthetic (57,58). 

The following materials serve as ingredients for foam plastics the polymers, blowing agents, hardeners, plastifiers, lubricants, stabilizers, fillers, and other substances. 

When heated, azodicarbonamide breaks apart into gaseous carbon monoxide, nitrogen, and ammonia. Azodicarbonamide is used as a foaming agent in the polymer indushy. (a) Add nonbonding electron pairs and multiple bonds as required to complete the Lewis stmcture of this molecule, (b) Determine the geometry around each inner atom. 

Distinctly different approaches to avoid these problems and still achieve high viscosities were conceived and applied. The different approaches can be categorized as 1) preparation of emulsions or foams and 2) addition of crosslinkers to the polymer. Two separate processes which utilized crosslinking of polymer gelling agents were pursued. These are the use of secondary (or delayed) gelling agents and the use of metallic crosslinkers added on-site. 

Foams are commercially produced several ways. Some polymerization processes produce their own foam. Polyurethanes, for example, are very exothermic. When they are formed, if a little water is present, CO2 will be a by-product. As the polymer forms, the CO2 will cause closed cell foam. As another example, a blowing agent can be injected into the molten polymer. The agent will later decompose, giving off a gas when the polymer is heated to melting. Epoxy resins are expanded into foams this way. 

Shutov FA (1991) Blowing agents for polymer foams. In Klempner DC, Frisch KC (eds) Handbook of polymeric foams and technology. Hanser, Munchen, chap 17... 

Improved compositions useful for the production of foamed rotomoulded articles are provided. The compositions of the invention are comprised of a first thermoplastic resin component which is an ethylene polymer in pellet form containing a foaming agent and a second thermoplastic resin component which is a powder consisting of a mixture of different particle size and melt index ethylene polymers. An improved process for producing foamed rotomoulded articles having uniformly foamed interiors and smooth exterior skins which are snbstantially free of surface defects is also provided. 

Patent Number US 5554661 A 19960910 CLOSED CELL, LOW DENSITY ETHYLENIC POLYMER FOAM PRODUCED WITH INORGANIC HALOGEN-FREE BLOWING AGENTS... 

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