Polyamide foams

Polyamides are temperature- and solvent-resistant polymers, and, therefore, these foamed products have the same advantages as the basic polymers. The first polyamide foam was prepared by the reaction of an organic diisocyanate and a carboxyl-terminated polyester (71). 

The reaction of NCO groups and carboxylic acid groups resulted in the formation of amide linkages and carbon dioxide as blowing agent. This reaction has led to the invention of urethane foam preparation, and the polyurethane industry has become one of the biggest plastic industries. A model reaction of a polyamide foam formation is shown below  

Component 2 was prepared by mixing 10 g of toluene, 1 g of silicone surfactant (Toray SH-193), and 7.6 g of hexamethylene diisocyanate. The two components were mixed in a container for 15 seconds. Rise time was 35 seconds, and the foam density was 0.042 g/cm. Aliphatic diisocyanates such as hydrogenated MDI and m-xylylene diisocyanate also act as effective activators, but aromatic isocyanates, such as MDI, TDI, were found not to be effective. 

Ferrigno, T.H, Rigid Plastic Foams (2nd Edition), Reinhold Publishing Corp., New York (1967). 

Saunders, J.H. and Frisch, K.C., Polyurethanes, Chemistry and Technology, Volume I and 2, Interscience Publishers, New York (1962) 

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The foams obtained were polyamide foams and not polyurethane foams, as shown by the model reaction A. This method was invented by Hoechtlen and Dorste in 1941 (121). 

In the process of polyamidation foaming of the polymer was not observed. Thermal stability of the dyes is satisfactory at warming - up for 48 hours and this shows that their introduction at the stage of - caprolactam polyamidation does not deteriorate PCA properties. 

Monofunctional, cyclohexylamine is used as a polyamide polymerization chain terminator to control polymer molecular weight. 3,3,5-Trimethylcyclohexylamines ate usehil fuel additives, corrosion inhibitors, and biocides (50). Dicyclohexylamine has direct uses as a solvent for cephalosporin antibiotic production, as a corrosion inhibitor, and as a fuel oil additive, in addition to serving as an organic intermediate. Cycloahphatic tertiary amines are used as urethane catalysts (72). Dimethylcyclohexylarnine (DMCHA) is marketed by Air Products as POLYCAT 8 for pour-in-place rigid insulating foam. Methyldicyclohexylamine is POLYCAT 12 used for flexible slabstock and molded foam. DM CHA is also sold as a fuel oil additive, which acts as an antioxidant. StericaHy hindered secondary cycloahphatic amines, specifically dicyclohexylamine, effectively catalyze polycarbonate polymerization (73). 

As of 1992, the first specialty platable plastic, acrylonitrile—butadiene—styrene (ABS) terpolymer (see Acrylonitrile polymers, ABS resins), is used ia over 90% of POP appHcatioas. Other platable plastics iaclude poly(pheayleae ether) (see PoLYETPiERs), ayloa (see Polyamides), polysulfoae (see Polymers CONTAINING sulfur), polypropyleae, polycarboaate, pheaoHcs (see Pphenolic resins), polycarboaate—ABS alloys, polyesters (qv), foamed polystyreae (see Styrene plastics), and other foamed plastics (qv). 

Amines or amides Alkyl amines (iindecyloctyl and diamyl methyl amine) polyamides (acyl derivatives of piperazine) Boiler foam sewage foam fermentation dye baths... 

Various elastic elements are added to disposable sanitary products. Strands of lycra, natural rubber, polyurethane foam, and other elastic laminates are applied to provide good fit and avoid leakage. These are attached with adhesives. While non-PSA formulas such as polybutene-based [64] and polyamide [65] adhesives have shown utility, as well as benefits in terms of resistance to baby oils and lotions, adhesives based on styrenic block copolymers still dominate. SBC-based... 

Polyalkylene polyamides and other nonsilicone synthetic antifoams are particularly useful in controlling foaming problems. These chemicals also provide defoaming and demulsification benefits. 

In addition, even where foaming is not a specific problem in a boiler, carryover may occur, especially in lower pressure boilers with very high TDS (i.e., over 10,000 to 15,000 ppm TDS) because of the collapse of surface bubbles. This leads to BW aerosol generation and entrainment of the spray in steam. Under these circumstances, antifoam agents such as polyamides are useful in preventing these entrainment problems. Furthermore, the antifoaming action of polyamides is often enhanced by protective colloid materials such as tannins, and consequently, formulations containing polyamide emulsions in an alkaline tannin base are available. 

Semicrystalline partial aromatic polyamides, 139 Semicrystalline polyesters, 45 Semicrystalline polymers, melting temperatures of, 33 Semirigid foams, 203 tests for, 244 Sensitization, 246... 

The ester class also comprises natural oils, such as vegetable oil [75] spent sunflower oil [940,941,992,993] and natural fats, for example, sulfonated flsh fat [161]. In water-based mud systems no harmful foams are formed from partially hydrolyzed glycerides of predominantly unsaturated Ci6 to C24 fatty acids. The partial glycerides can be used at low temperatures and are biodegradable and nontoxic [1280]. A composition for high-temperature applications is available [1818]. It is a mixture of long chain polyesters and polyamides. 

Various polymeric materials were tested statically with both gaseous and liquefied mixtures of fluorine and oxygen containing from 50 to 100% of the former. The materials which burned or reacted violently were phenol-formaldehyde resins (Bakelite) polyacrylonitrile-butadiene (Buna N) polyamides (Nylon) polychloroprene (Neoprene) polyethylene polytriflu-oropropylmethylsiloxane (LS63) polyvinyl chloride-vinyl acetate (Tygan) polyvinylidene fluoride-hexafluoropropylene (Viton) polyurethane foam. Under dynamic conditions of flow and pressure, the more resistant materials which binned were chlorinated polyethylenes, polymethyl methacrylate (Perspex) polytetraflu-oroethylene (Teflon). 

P.B.15 1 is also applied in polystyrene, polyamide, polycarbonate (in which it is heat stable up to 340°C), PUR foam materials, and cast resins. It should be noted, however, that the hardening of cast resins which are based on unsaturated polyesters is usually much retarded. 

P.B.15 3, like stabilized a-Copper Phthalocyanine Blue, markedly affects the hardening of unsaturated polyester cast resins. The list of applications also includes PUR foam materials, office articles, such as colored pencils, wax crayons, and water colors, as well as spin dyeing of polypropylene, polyacrylonitrile, secondary acetate, polyamide, polyester, and viscose. Used in polyester spin dyeing, P.B.15 3 satisfies the thermal requirements of the condensation process (Sec. 1.8.3.8). 1/3 and 1/25 SD samples equal step 7-8 on the Blue Scale for lightfastness. Textile fastnesses, such as stability to wet and dry crocking are perfect. 

As shown in Figure 2.33, polyethylene has the highest consumption (nearly 60%) in both thermoplastic and thermoset (PEX) forms, and also foamed PE (2%). PVC is second (roughly 30%) and the others are polypropylene,TPEs, polyamide, fluoropolymers. .. 

Effect of silanes on the compressive properties of a polyamide cured epoxide silica microballoon syntactic foam (cured at 2 l°C for 14 days. 5 w/r addition, nominal density 0.35 g/cm- )... 

Table 16 shows similar data for a polyamide cured epoxide/silica foam at a nominal density of 0.35 g/cm . All the silanes produced an increase in compressive strength and strain to failure, but showed less effect on the compressive modulus. In general this series of foams were stiffer than the anhydride cured series and the silanes showed a different order of merit. Although it cannot be claimed that the level of addition chosen was necessarily optimum in all cases the value of silanes in increasing the compressive strength is obvious. 

Figure 7 shows the family of curves for anhydride cured foams containing 5 wt% of various silanes and it can be seen that although every silane improved the energy absorbing efficiency to a marked extent, the APES foam was the most efficient, followed closely by MPS and AAMS. Figure 8 shows similar data for the polyamide cured epoxide foams, from which it can be seen that the MPS foam was the most efficient. In these foams the flat response only held up to 25-30% strain. 

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