Poly urethane Foams

The fire behavior of the foams can be tested with a cone calorimeter, according to standard test protocols (10,12). The test method is used to determine the ignitabUity, heat release rates, mass loss rates, effective heat of combustion, and visible smoke development of materials and products. 

In this test the foam specimens are ignited with a conical radiant heater, the thermal flux applied on the specimen surface being 50 kW m . The specimens tested had a size of 100 mm by 100 mm with a thickness of 50 mm. The samples are wrapped in aluminum foil in order to have only the upper surface exposed to the radiant heater. Two specimens are used for each measurement and the results are averaged. 

A rigid poly(urethane) foam or poly(isocyanurate) foam can be prepared by reacting a poly(ol) and an isocyanate in the presence of a 

1-Dichloro-l-fluoroethane was used as the blowing agent for the preparation of rigid poly(urethane) foams. However, this compound has the capability to destroy the ozone layer. So it has been decided to prohibit the use of this compound as a blowing agent. 

Attention has been focused to 1,1,1,3,3-pentafluoropropane as an alternative compound, because 1,1,1,3,3-pentafluoropropane contains no chlorine atom in the molecule and thereby has no capability to destroy the ozone layer (13). 

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The same dibutyltin compounds are used in the industrial manufacture of poly(urethane) foams, the first step in which involves the addition of a polyether glycol to 2,4-diisocyanotoluene, to produce the urethane prepolymer having isocyanate end-groups. 

Figure 12.16 NIR. diffuse reflectance spectra of 26 poly(urethane) foams, used to demonstrate different classification methods.

Figure 12.24 Dendrograms obtained from hierarchical cluster analysis (HCA) of the NIR. spectra of the poly(urethane) foam samples (shown in Figure 12.16), (A) using the first two PCA scores as input, (B) using the first five PCA scores as input. In both cases, the Mahalanobis distance measure and the nearest-neighbor linkage rule were used.

Their low surface tension results in their utilization in the paint industry as flow, gloss and finish improvers. Silicone oil additives enable effect paints to be formulated such as moire effect paints. Their surface and interfacial activity enables their use as defoaming agents and as foam stabilizers for poly(urethane) foams. 

Carbon foams were also prepared by impregnating poly(amide acid) into poly(urethane) foams used as template, followed by imidization and carbcmization [2]. The foams were tested as adsorbents for atmospheric humidity and also as supfmrts for anatase-type TiOi photocatalysts. In Fig. 47, clmnges in pore morphology with impregnation of poly(imide) and carbonization at 1273 K are shown. 

Poly(urethane) foams based on polyethers have now largely replaced polydiene rubbers in upholstery and flammability is a major disadvantage compared with traditional upholstery. A major problem is that it is not the fire itself that kills people but the toxic fumes that are produced in the smoke and this is exacerbated by certain types of flame retardant. There are no simple solutions to this problem. Foams in their very nature have a large surface area and a developing fire thrives on the accessibility of fuel from the exposed foam (Chapter 3). The most promising solution is to make the textile fabric surrounding the foam non-flammable so that the fire never reaches the foam itself. 

Poly(urethanes), like the polyamides, are attractive to rodents who use them as a source of nutrients because of their nitrogen content. Poly(urethane) foams are also micro-biodegradable if left in humid environments and the loss of strength due to biodegradation is a significant problem in some applications. 

An important way of inhibiting the ignition of polymeric materials is to increase the formation of carbonaceous chars at the expense of combustible fuels. Ammonium phosphate has been used for many years as a flame retardant for cotton and is known to work by catalysing the formation of carbon and water. It is also effective in poly(urethane) foams which form a major component of much domestic upholstery. 

Silicone emulsiflyer, for flexible poly(urethane) foam ... 

Silicone emulsiflyer, for flexible poly(urethane) foam, 509 Niax L-6900 Surfactant, 509 Nirez 2150/7042 Terpene phenol flow modifler, 166 Nomex ... 

REPORT OF RESEARCH ON THE CHARACTERISTICS OF RIGID POLY-URETHANE FOAM FOR THERMAL INSULATION APPLICATIONS. TECH. REPT. 

Plasticized poly(vinyl chloride) (PVC), poly(urethane)s, poly(eth-ylene) (PE), and poly(ester)s are particularly sensitive to microbial attack. Flexible PVC is by far the main plastic in which biostabilizers are incorporated, followed by poly(urethane) foams, and other resins. PVC itself is resistant to microbial attack, however, plasticizers, fillers, pigments, lubricants, and other additives used in PVC are... 

Although more environmentally acceptable blowing agents have come into use that are typically hydrohalocarbons, these are generally not as effective as those commonly used previously and there is, therefore, a continuing need for enhancements in the process of making rigid poly(urethane) foams and m the properties of the foams themselves. 

Antagonism between antimony oxide and phosphoms flame retardants has been reported in several polymer systems, and has been explained on the basis of phosphoms interfering with the formation or volatilization of antimony haUdes, perhaps by forming antimony phosphate (12,13). This phenomenon is also not universal, and depends on the relative amounts of antimony and phosphoms. Some useful commercial poly(vinyl chloride) (PVC) formulations have been described for antimony oxide and triaryl phosphates (42). Combinations of antimony oxide, halogen compounds, and phosphates have also been found useful in commercial flexible urethane foams (43). 

Hydrosilation reactions have been one of the earlier techniques utilized in the preparation of siloxane containing block copolymers 22,23). A major application of this method has been in the synthesis of polysiloxane-poly(alkylene oxide) block copolymers 23), which find extensive applications as emulsifiers and stabilizers, especially in the urethane foam formulations 23-43). These types of reactions are conducted between silane (Si H) terminated siloxane oligomers and olefinically terminated poly-(alkylene oxide) oligomers. Consequently the resulting system contains (Si—C) linkages between different segments. Earlier developments in the field have been reviewed 22, 23,43> Recently hydrosilation reactions have been used effectively by Ringsdorf 255) and Finkelmann 256) for the synthesis of various novel thermoplastic liquid crystalline copolymers where siloxanes have been utilized as flexible spacers. Introduction of flexible siloxanes also improved the processibility of these materials. 

Uses Preparation of propylene and dipropylene glycols, poly (propylene oxide), lubricants, oil demulsifiers, surfactants, isopropanol amines, polyols for urethane foams solvent soil sterilant fumigant. 

A similar result was seen in the performance of a sample of hydrophilic poly-urethane-grafted reticulated foam without carbon. (Figure 4.15). Figure 4.16 shows the analysis of the effect of the carbon-impregnated foam. It is clear from these data that the carbon-impregnated foam showed significant improvement in effectiveness. In all the extractions cited below, the CoFoam contained about 1.7 g carbon. 

A typical refrigerator appliance cabinet consists of an outer metal cabinet, an inner plastic liner, typically made from ABS or HIPS, and an insulating polymer foam core, typically a poly(urethane) (PU) foam (29). 

Burning may be considered another means of oxidation. Non-burning plastics are a must in commercial constructions according to building codes and are often required for automotive, electronic, and electrical applications. From the numerous thermoplastics, only the halogen-containing polymers, polyamides, polycarbonate, poly(phenylene oxide), polysulfone, and polyimides are self-extinguishing. Even these, such as poly (vinyl chloride), may become flammable when plasticized with a flammable plasticizer. Fire control can be the key to volume use of plastics. Polyester panels, urethane foam, and PVC tarpaulins account for nearly 90% of all fire retardants consumed. Consumption in 1967... 

Modification of poly(carbodiimide) foams with polyols afford hybride foams containing urethane sections. However, the thermal stabilities of the poly (urethane carbodiimide) foams are lower. Using isocyanate trimerization catalysts, such as l,3,5-tris(3-dimethylaminopropyl)hexahydro-s-triazine, in combination with the phospholene oxide catalyst gives poly(isocyanurate carbodiimide) foams with improved high temperature properties. The cellular poly(carbodiimide) foams derived from PMDI incorporate six-membered ring structures in their network polymer structure. ... 

They found the heat of reaction for 80 20 TDI and water to be 38.3 1.74 kcal mole", and that for 80 20 TDI and a poly(oxy-propylene)triol to be 42.5 0.76 kcalmole" (with two equivalents of NCO per mole in each case). Both separate reactions gave data which fit second-order kinetics up to 50% reaction. Preliminary attempts at calculating kinetic coefficients for both reactions during polyurea—urethane foam formation were given. It is believed that further efforts along this line will be needed to clarify the kinetics satisfactorily, however. 

A research program to have benzylic ether-type resin react with polyisocyanate for producing polyurethane or urethane-modified poly-isocyanurate foam is being promoted. A foam which has intermediate properties between phenolic foam and polyurethane foam can be produced. 

Naugard PS-30 is a liquid amine antioxidant typically used with phenolic antioxidants, phosphites, and synergists in poly-ether polyols to inhibit physical/color scorch associated with the production of flexible urethane foam. 

Figure 1. Compound growth rate of poly ether flexible urethane foam.

Foam-blowing rigid poly-urethane CFC-ll Reduced CFC option 30-50 2.24 97... 

Starch utilization in plastic and rubber compositions began in the 60s and 70s, with oxidised starch in rubber and other polymers, such as urethane foams, poly(vinyl alcohol) and copolymers of poly(ethylene-co-acrylic acid) formulations, and as a filler in plasticized polyvinyl chloride (PVC) [37,39]. In another technique, gelatinized starch was mixed with PVC latex and the water was removed to give a PVC-starch composition, which was mixed with a PVC plasticizer such as dioctyl phthalate (DOP). 

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