Phenol-formaldehyde foam

Lowe, A. J. et aL The phenol formaldehyde foams. 4./SPI Internal. Cellular Plastics Conf., Montreal, 1976... 

BS 5946 1980 Method of Test for Detetmination of die Funking Behaviour of Phenol-Formaldehyde Foam, 9 pp... 

BS. 927 for phenol-formaldehyde foam uses the same basic technique, but the specimen size at 50 mm cube is different, and the period of immersion is set at seven days. Similarly BS 4840. Part 1, for rigid polyurethane foam in slab form uses the same sample size and immersion period. 

The friability of a rigid foam is not an easy property to determine, and it is seldom used as a quality control measurement. However, for certain materials such as phenol-formaldehyde foam it can be a useful tool in formulation work to ensure that the product is suitable for the application area. In certain instances the test method is best adapted to the foam being tested, for example the time duration of the test may be shortened if the material is being abraded too harshly. 

Fig. 2.24 Oxygen indices of various rigid plastics foams as functions of temperature I phenol/formaldehyde foam filled with pearlite 2 modified closed-cell phenol/formaldehyde foam 3 polyisocyanuratc foam 4 polyurethane foam filled with pearlite 5 polyurethane foam 6 open-cell phenol/formaldehyde foam...

Fig. 3.153 Surface temperatures on chipboard/phenol formaldehyde foam/chipboard sandwich panels during combustion of 10 dm of gasoline... 

There was no clearance between the core and skin in the tested sandwich pieces, which is an important factor in upgrading the flammability behaviour. Any material used in the manufacture of sandwich panels must be at least as fire resistant as the skin and core materials. For example, when phenol/formaldehyde foam cored sandwich elements were mounted on firwood frames, the flames were conducted by the frame, thus enhancing the fire risk. 

To prepare thermal insulating materials, Carvalho et al. (2003) prepared phenolic and lignophenolic (lignin-phenol-formaldehyde) foams and determined their thermal conductivities 0.057 W m K (density of 0.12 g cm ) for phenolic foam and 0.072 W m" K" (density of 0.45 g cm ) for lignophenolic foam. Tondi et al. (2009) prepared tannin-based rigid foams with thermal conductivity values between 0.024 and 0.030 W m K" for densities between 0.08 and 0.12 g cm", respectively. 

Foams prepared from phenol—formaldehyde and urea—formaldehyde resins are the only commercial foams that are significantly affected by water (22). Polyurethane foams exhibit a deterioration of properties when subjected to a combination of light, moisture, and heat aging polyester-based foam shows much less hydrolytic stabUity than polyether-based foam (50,199). 

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

Otner Collectors Tarry particulates and other difficult-to-handle hquids have been collected on a dry, expendable phenol formaldehyde-bonded glass-fiber mat (Goldfield, J. Air Pollut. Control A.SSOC., 20, 466 (1970)] in roll form which is advanced intermittently into a filter frame. Superficial gas velocities are 2.5 to 3.5 m/s (8.2 to 11.5 ft/s), and pressure drop is typically 41 to 46 cm (16 to 18 in) of water. CoUection efficiencies of 99 percent have been obtained on submicrometer particles. Brady [Chem. Eng. Prog., 73(8), 45 (1977)] has discussed a cleanable modification of this approach in which the gas is passed through a reticulated foam filter that is slowly rotated and solvent-cleaned. 

Phenol-formaldehyde (PF) resins were synthesized to manufacture non-flammable insulating foam. When alkali catalyst, for example, barium hydroxide (Ba(OH)2), was present, lesol resins are produced[l]. In the analj s of molecular species of resol, capillary GC-MS had been used to separate hemiformal-type compoimds(acetylated hydroxybenzylhaniformals)... 

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). 

Debate is continuing on the safety and toxicity of formaldehyde and its products, especially urea-formaldehyde foam used as insulation in construction and phenol-formaldehyde as a plywood adhesive. Presently the TLV-STEL of formaldehyde is 0.3 ppm. Formaldehyde is on the Reasonably Anticipated to Be Human Carcinogens list. 

Hydro Foam Expanded phenol-formaldehyde Smithers... 

Phenol-formaldehyde (PF) was the first fully synthetic macromolecular material ( Bakelite , 1907). In a slightly precured condition and provided with fillers, it is, as a moulding powder, available for processing into end-use articles such as bulb fittings, switch housings, coils, laminated wood and foam for thermal insulation. 

Cellular urea-formaldehyde and phenolic resin foams have been used to some extent in interior sound-absorbing floors [101]. In general, cost, flammability, and cleaning difficulties have prevented extension into the acoustic tile market. Plastic foams are used in anechoic chambers [66]. 

The relation between the cell size and the strength of phenol-formaldehyde plastic foams shows that, for a mean cell diameter of less than 0.2-0.3 mm, their compressive strengths and Youngs moduli increase considerably as compared to foams with large cells, It has been found that for many flexible foam types the tensile strength and ultimate elongation are the higher the smaller the cells ss.ioo)... 

Neither a historical review nor a complete story of this field of polymer making is presented here. Rather, this is a series of views of the chemistry and procedures, from which one may obtain some idea of the potential as well as of the limitations of the methods. The discussion includes only reactions which yield essentially linear polymers, bypassing polyurethane foams and phenol-formaldehyde condensates. 

Polyisocyanurate foams, polyurea foams and phenolic foams are growing rapidly in recent years. Urea-formaldehyde foams disappeared recently from the U.S. market. Rubber foams and pyranyl foams are no longer available in the worldwide market. 

Use Production of polyurethane foams and elastomers, in phenol-formaldehyde resins to improve water and alkali resistance bonding rubber to rayon or nylon. 

During the past decade, urea formaldehyde and phenol formaldehyde resin binders have contributed greatly to the progress of wood industries. Formaldehyde is widely used as a major component in the production of building materials, such as particleboard and plywood, and in urea formaldehyde foam insulation. However, the emissions of formaldehyde from these products create considerable concerns not only in the working environments but also in residences, mobile homes, and office buildings. These concerns have also been stimulated by reports on the health effects and carcinogenicity associated with formaldehyde exposure. 

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