Foamability

Flexible foams are resiUent open-ceU stmctures with densities varying from 25—650 kg/m, depending on the choice of the raw materials. Most flexible foams are produced in the form of a slab or bun in a contiauous process in widths up to 2.4 m and thicknesses up to 1.2 m. A Hquid foamable mixture is pumped onto a conveyor, which moves through a tunnel where reaction and foaming occur (101). Similar mixtures can be placed in a mold and allowed to foam. This process is used in the manufacture of automobile seats (see Foamed plastics). 

PS Foams. The eady history of foamed PS is available (244), as are discussions of the theory of plastic foams (245). Foamable PS beads were developed in the 1950s by BASF under the trademark of STYROPOR (246—248). These beads, made by suspension polymerization in the presence of blowing agents such as pentane or hexane, or by post-pressurization with the same blowing agents, have had an almost explosive growth, with 200,000 metric tons used in 1980. Some typical physical properties of PS foams are Hsted in Table 10 (see Foamed plastics). 

However when the SF cross-section is analyzed, its composite nature still results in a twofold increase in rigidity, compared to an equivalent amount of solid plastic, since rigidity is a cubic function of wall thickness. This increased rigidity allows large structural products to be designed with only minimal distortion and deflection when stressed within the recommended values for a particular foamable plastic. 

Property ASTM Test Phenolics Foamedin Syntactic Place Castable Polyvinyl Chloride Rigid Closed Cell Phenylene Oxide Foamable Resin Polycarbonate Polystyrene Medium-Density Foam Polystyrene Molded Extruded Polyurethane Rigid Closed Cell... 

The foamabilities of C14 and C18 AOS were very small in 54, 180, and 360 ppm calcium carbonate water hardness. Enhanced foamability was observed with C16 AOS in 180 and 360 ppm water hardness. 

Experimental soap exhibited better foamability and better detergency. 

Foamability of phosphoric acid esters in aqueous solutions is in general only moderate, with the acid phosphates showing a better stability against water hardness than the alkali or amine salts. 

The maximal accessible depression of the surface tension of aqueous solutions of disodium alkanephosphonates is strongly controlled by the length of the carbon chain. There is a similar dependence of foamability on the length of the alkyl chain [188], as is shown in Table 8. 

Ethylene oxide adducts of alkanephosphonic acids exhibit a better solubility in water and partly an interesting depression of the surface tension in aqueous solutions (Table 9). Although foamability and wetting rate lie in a medium range, they possess no emulsifying ability. 

In the case of N-containing phosphonates some interesting data were observed [190]. Alkanephosphonic acid bisdiethanolamides, RPO(NCH2CH2OH)2, show good wetting performance and foamability at an alkyl chain length of C,0 and C12 according to Table 10. 

Similar effects are obtained by using the bisdiisopropanolamides of alkanephosphonic acids. The maximum wetting performance and foamability may be observed at an alkyl chain of C8, according to Table 11. 

The foamability of the xylans tested [128] was low in comparison to a commercial whipping protein DIOO. Only the highly viscous beech wood xylan and the rye bran AX-protein complex exhibited remarkable foaming activity, which was similar to that of gum arable. As the MGX polymers contain considerable amounts of uronic acid side chains, this may play a role in their foaming activity together with the presence of low amounts of Ugnin. 

Gendron and Vachon (36), reviewing Park s research (274) on PP foam, defined a foamability factor F from the tan S of the PE melt (at 190 °G and 1 Hz), the average cell diameter D and the foam density p as ... 

Dallas, Texas, 6th-10th May, 2001, paper 438 EFFECTS OF BLENDING OF BRANCHED AND LINEAR POLYPROPYLENE MATERIALS ON THE FOAMABILITY... 

A foamable isotactic polypropylene homopolymer is obtained by metallocene catalysis and has a molecular weight distribution and density, which fall within broad ranges. It may be prepared in a multiple stage polymerisation process nsing the same metallocene component in at least two stages. 

Patent Number US 6069183 A1 20000530 FOAMABLE COMPOSITION USING HIGH DENSITY POLYETHYLENE... 

Patent Number US 6008262 A 19991228 FOAMABLE COMPOSITIONS COMPRISING LOW VISCOSITY THERMOPLASTIC MATERIAL COMPRISING AN ETHYLENE ALPHA-OLEFIN... 

Patent Number US 5928584 A 19990727 FOAMABLE COMPOSITIONS FOR ROTATIONAL MOULDING... 

An integrally monlded composite article comprised of (I) a nonfoam layer formed from a thermoplastic elastomer powder composition (A) and (II) a foam layer formed from a foamable composition comprised of (i) (B) a thermoplastic synthetic resin powder, and (C) a heat decomposable foaming agent and (D) a liquid coating agent, wherein the thermoplastic elastomer powder (A) is comprised of a composition of an ethylene-alpha-olefm copolymer mbber and a polyolefin resin or thermoplastic elastomer powder comprised of a partially crosslinked composition of an ethylene-alpha-olefm copolymer mbber and a polyolefin resin, the thermoplastic elastomer powder having a complex dynamic viscosity at 250 deg C and a freqnency of 1 radian/sec of not more than 1.5x1,000,000 poise and having a Newtonian viscosity index n, calculated by a specific formula. 

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