Polyurethane foam porous

Gaseous and particulate pollutants are withdrawn isoldnetically from an emission source and collected in a multicomponent sampling train. Principal components of the train include a high-efficiency glass- or quartz-fiber filter and a packed bed of porous polymeric adsorbent resin (typically XAD-2 or polyurethane foam for PCBs). The filter is used to collect organic-laden particulate materials and the porous polymeric resin to adsorb semivolatile organic species (com-... 

X. Miao, Y. Hu, J. Liu, A.P. Wong, Porous calcium phosphate ceramics prepared by coating polyurethane foams with calcium phosphate cements. Mater. Lett. 58 (2004) 397 02. 

A biomass (microorganisms used for reduction of contaminants) support matrix is used, consisting of porous polyurethane foam with a surface area greater than 200 ft /ft (670 m /m ). 

This support matrix is coated with PAC using a proprietary procedure that maintains the carbon in an activated state. Use of this porous polyurethane foam overcomes a difficulty that technology developers have had in identifying materials that are suitable support for the biomass when used to remove organic pollutants from the vapor phase. 

Wake, M.C., Patrick, C.W and Mikos, A.G., Pore morphology effects on the fibrovas-cular tissue growth in porous polymer substrates. Cell Transplant. 3, 339,1994. Gion, T, Shimada, M., Shirada M., et al. Evaluation of a hybrid artificial liver using a polyurethane foam packed-bed culture system in dogs. Journal of Surgical Research 82, 132-136 1999. 

Tuerker and Mavituna immobilized Trichoderma reesei within the open porous networks of reticulated polyurethane foam matrices. Growth pattern, glucose consumption, and cellulase production were compared with those of freely suspended cells. The method of immobilization was simple and had no detrimental effect on cell activity. Hundreds of similar projects could be cited. Not all rated the use of polymethane as the preferred technique. If a statistical analysis were conducted on aU the immobilization literature, we are sure that no single technique would be dominant. However, the combination of ease of immobilization, cost of materials, flow-through properties, control of flux rate through the immobilizing membrane, high surface-to-volume ratio, and other factors make polymethane a viable substratum for the continuous production of proteins. 

Porous polyurethane foams possess many of the same attributes as the macroreticular resins and, in fact, the range of applicability is quite similar (16, 18, 60, 62, 63, 64, 65). 

Summarizing, it appears that the macroreticular resins such as XAD-2, XAD-4, and Chromosorb 102 or porous polyurethane foam can be considered as alternatives to the glycol impinger for sampling many of the common pesticides and related chemicals in air. The glycol impinger has been more thoroughly tested, while the resins and foams are clearly to be preferred... 

FIGURE 3.10 Scanning electron microscopy imaging of the porous matrix of polyurethane foam. Virgin foam (top) and smoldered char (bottom). 

As the reaction propagates, the oxygen inside the porous matrix is completely consumed leaving residual char. Figure 3.11 shows a picture of smoldered polyurethane foam. The foam was ignited at the top of the sample and the reaction was allowed to propagate downward leaving a black char behind. 

A smoldering reaction is not always established when heat is applied to a porous fuel susceptible to smolder. Actually, the conditions for the onset of smoldering are in some cases (i.e., polyurethane foam) very restrictive. The following possible pathways have been established as viable when heating a fuel susceptible to smolder. 

Embryogenic rice calli tend to form larger clumps during cultivation. Therefore, immobilization of the calli has hardly been carried out until now. Porous supports such as polyurethane foam have often been used for the immobilization of mycelial cells [64, 65] and plant cells [66-68]. In almost all cases, effective production of biological materials by the immobilized cells has been reported. To avoid the damage due to the hydrodynamic stress, we proposed the immobilization culture of rice callus using a macroporous urethane foam support. A turbine-blade reactor (TBR), which has been developed for hairy root culture, was also used in the culture. In the culture space, polyurethane foam was added as an immobilization support. 

Polyakov, Yu. N., Tarakanov, O. G. Macrostructure Model for Flexible Polyurethane Foams, in Mechanics of Fibrous and Porous Systems, Riga Zinatne Press 1967, pp. 323 (Russ.)... 

A special case of porous polymer sorbent is polyurethane foam, which can be used to collect large air samples up to 100 m (Ligocki and Pankow, 1985). A major application of PU foams is the trapping of high boiling organopesticides such as lindane or per-methrine. 

Adsorption Cellulose, chitine (chitosan), nylon, polypropylene fibres, polymer nets and membranes, wood, lignine, ion-exchange resins, polyurethane foam, polyacrylamide (Porous) glass, clay,bentonite, zeolithes, ceramics, meso-porous silica, metal oxides (Fe, Ti, Mg), metal phosphates, mineral powder... 

McHugh and Krukonis ( ) have demonstrated with the aid of SEM, that polypropylene preforms can be rendered porous by extraction with supercritical CO2 and propylene. However, these investigators noted that SCF extraction of the preformed polymer sheets at higher pressures and temperatures deformed the polymer matrix leading to a fused appearance when examined by SEM and a concomitant decrease in porosity. Similar interaction between porous polyurethane foam and supercritical CO2 reported by Smith and coworkers (J) lead to a physical alteration of the exposed sorbent. Such pressure-induced structural changes lead to a decrease in available surface area for sorbate adsorption. 

One of the ways of improving wear resistance and reliability of sealing elements is filling of porous semis by components able to form a secondary porous system [146]. For example, a blank of a polyurethane foam is impregnated with a mixture of dispersed PE with an inhibited lubricant. The formation of a gel under certain temperature regimes is accompanied by phase distribution within the material. The contact surface of the blank is cleaned by acetone to remove the lubricant. As the acetone evaporates, the prepared zones are zinc-plated and pores freed from the lubricant become filled with zinc. This makes the coating adhere strongly to the surface and allows zinc to penetrate to a depth acceptable for wear limits. 

Gesser, H. D Chow, A., Davis, F. C., Uthe, J. F Reinke, J. The Extraction and Recovery of Polychlorinated Biphenyls (PCB) Using Porous Polyurethane Foam, Anal. Lett. 4,883 (1971)... 

Sample passed through porous polyurethane foam or Tenax desorbed by soxhiet extraction extract cleaned by column chromatography and fuming H2SO4 and fraction concentrated... 

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