Foamed block

Chlorofluorocarbon-blown foam blocks are used to insulate the walls and roofs of some buildings, thus reducing heat losses and helping to conserve fossil fuels. In this area, polyurethane foam competes with polystyrene foam, which until recently was blown with dichlorodifluoromethane (CFC 12) but is now blown with a mixture of chlorodifluoromethane (HCFC 22) and 1 -chloro-l,l-difluoroethane (HCFC 142b). 

As much as a quarter of a flexible foam block can be wasted in downstream processing into flnished products. Thanks to the efforts of process technologists and engineers, this scrap material can be recycled by at least 17 basic methods. However, only a few have found significant practical applications. Most other PU scrap ends up as uncollectable domestic waste with perhaps one key exception, materials from end-of-life vehicles. WESTERN EUROPE-GENERAL Accession no. 709465... 

Note 1 Original PU foam blocks to meet test for PU foam. 

PU foam crumb must also have been made from PU foam block which meet the relevant requirements. Polystyrene foam beads are considered to have passed the test if the beads cascading from the specimen consistently extinguish the gas flame (Table Vil). 

Packing Gift box and master cartoon Foam blocks Instruction manual Poly bag 2.50 2.502 ... 

The creep stress was assumed to be shared between the polymer structure yield stress and the cell gas pressure. A finite difference model was used to model the gas loss rate, and thereby predict the creep curves. In this model the gas diffusion direction was assumed to be perpendicular to the line of action of the compressive stress, as the strain is uniform through the thickness, but the gas pressure varies from the side to the centre of the foam block. In a later variant of the model, the diffusion direction was taken to be parallel to the compressive stress axis. Figure 10 compares experimental creep curves with those predicted for an EVA foam of density 270 kg m used in nmning shoes (90), using the parameters ... 

Journal of Cellular Plastics 37, No. 1, Jan. 2001,p.21-42 THERMAL CONDUCTIVITY OF A POLYETHYLENE FOAM BLOCK PRODUCED BY A COMPRESSION MOULDING PROCESS Martinez-Diez J A Rodriguez-Perez M A De Saja J A Arcos y Rabago L O Almanza O A... 

The tedmological skin at foam block edges approximately doubles Ebr (Table 8). 

The mold material has a marked effect on the density distribution pattern in a foam block. It has been shown for the grade FRP-1 of phenolic foam in panels with aluminum or asbestos cement claddings that, due to the different thermoconductivity coefficients of the claddings, the thickness of the compacted layer may be 1.5 to 2.0 cm for aluminium and 0.5 to 1.0 for asbestos cement. For phenolic foams the variation of the volumetric weight across the depth of the intermediate layer of a three-layer panel may be described by the following equation (Fig. 7) ... 

Ymra and Yi are obtained from the relations y = 0,44y and y, = 16,3y , where y is the averaged volume weight of the foam block. The compaction gradient is 2.0 for asbestos cement and 0.70 for aluminum cladding layers. The calculated and experimental Ay distribution curves are in good agreement (Fig. 7). 

The cell aspect ratio, which is characteristic for foam anisotropy, can be determined by microscopically measuring the linear cell dimensions on sections cut from different portions of a foam block. The results of such measurements can only be representative of the morphology of certain portions of a cellular structure. A statistical analysis of samples cut of different block portions and in different directions with respect to that of expansion is a very difficult task. 

In the case of box foaming, the foam in a box must be kept in the box for post curing at room temperature. If the box foam is taken out immediately after foaming, many cracks may be formed. The same attention must be paid to bun foam (block foam). These foams must be post cured at ambient temperature, either by indoor or outdoor curing for at least a week. 

Alternatively, organisms such as protozoans may be collected on polyurethane foam blocks suspended in a stream which the system is designed to simulate and macroinvertebrate communities assembled on rocks held in plastic containers (Pontasch et al. 1989). 

Foam Block . [Boehme Filatex] Reacted silicone dispersion defoamer and antifoam for dyeing operations. 

Oil production generally increases as a result of the improved volumetric sweep caused by foam injection. Incremental oil production from down-dip wells is likely to be higher than that from up-dip wells because of a reduction in steam override. Changes in the steam-oil ratio (SOR) can provide a reliable indication of foam blocking if steam-drive is the primary displacement method. 

Injection of surfactant into the bottom zone limits foam blocking to the upper zones because the liquid surfactant stays in the bottom zone. 

A series of four PS foam samples with a density of 20 g/1 was made using the so-called vacuum process. Neostatic HB155 (an alkyl substituted, kationic ammonium salt) was, as the antistatic additive, added in concentrations of respectively 1, 2 and 4 %wt. This anti-static additive was added, dissolved in a constant amount of water, to the expanded PS particles and thoroughly mixed. This mixture was used to press PS foam block samples of 30 x 30 x 5 cm. Subsequently, samples of 9 x 9 x 0.42 cm were cut from these PS foam blocks to measure the electrical surface and volume resistivity. These samples were first stored, however, during six weeks at a temperature of 20 + 1 °C and a relative humidity of 50 %, to reach equilibrium moisture uptake conditions. 

Polymerization of trioxane witii BF3 etiierate as catalyst to produce polyoxymetiiylene Continuous manufacture of polym-etiiene foam blocks... 

PhenoKc foam is a light weight foam created from phenolic resins. It is used in a large range of applications, such as flower foam blocks, building thermal insulation, fire protection, damping, and civil engineering in a wide variety of shapes blocks, sheets, and sprayed foams. 

Polyurethane board can include a low density foam block for applications from styling models to cutter path verification, and styling. Low density master models from which vacuum-consolidated RP tools and components can be produced. 

Production process Lamination Block foam - Block foam RUF... 

The location of a thermobalance in the laboratory is of particular importance. The instrument must be isolated from mechanical vibrations. This can be achieved by placing the thermobalance on an isolation table. However, isolation tables are expensive and a more economical solution is to stack polystyrene foam blocks approximately 1 m high with a steel plate (2-3 cm thick) across the top, as an isolation stage. This will isolate the thermobalance from vibrations in... 

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