Foamed blown

Patent Number US 5405883 A 19950411 ETHYLENE POLYMER FOAMS BLOWN WITH ISOBUTANE AND 1,1-DIFLUOROETHANE AND A PROCESS FOR MAKING... 

Patent Number WO 9425255 A1 19941110 ETHYLENE POLYMER FOAMS BLOWN WITH... 

Figure 20. Effect of density on K-factor (foam blown with carbon dioxide) (212).

Figure 22. Aging of rigid urethane foam with cut surfaces (foam blown with CFC-11) (212).

In 1991 Vandichel and Appleyard (15) described a new promising approach for the production of "soft" flexible slabstock urethane foam blown exclusively by COj generated by the water-isocyanate reaction. These workers found that by the addition to the formulation of certain hydrophilic materials a substantial hardness reduction is obtainable, thereby permitting a considerable reduction, or even total elimination, of CFC-11 from some "conventional" foam formulations. The hydrophilic additive is called CARAPOR 2001. An example is a foam produced with an ILD value of 80N at a density of 21.5 kg/m" (1.34 Ib/ft ) (15). 

This situation is completely different today. The demand for new materials is large for many reasons insulating foams blown with CFC (chlorofluorocar-bons) are known to be environmentally dangerous because the chlorine released from the CFC in the upper atmosphere destroys the ozone layer. Insulating fiber materials are considered a health hazard because they release small fiber fragments, which can be inhaled and deposited in the lung tissue, where... 

Conventional rigid polyisocyanurate foams blown with HCFC-141b often suffer from poorer compressive strengths, dimensional stability and inferior inflammability properties when compared to foams blown with CFC-11. An improved isocyanurate conversion test by photoacoustic Fourier Transform Infra Red technique is introduced. The method is not limited to polyisocyanurate foam, as isocyanate conversion is an important parameter to follow in PU foams as well, especially in all carbon dioxide blown foams. The method is found to be quite reproducible and further statistical analysis to ensure the validity of this technique is under way. 8 refs. 

A - Soft foam B - Hard foam C - Soft and lower-density foam, blown with natural... 

The flammability of roofing foam blown with pentanes may have to be kept low by the use of flame retardant additives such as chlorinated phosphates. 

Prociak [27] studied the effect of parameters such as the method of sample preparation, the temperature gradient and the average temperature of measurement on the thermal conductivity of rigid PU foams blown with hydrocarbons and hydrofluorocarbons (HFC). The thermal insulation properties of different cellular plastics, such as rigid and flexible PU foams and expanded PS, were compared. The thermal conductivity and thermal diffusivity of foams were correlated with the PU matrix structure to demonstrate the effect of cell anisotropy on the thermal insulation properties of the rigid foams blown with cyclopentane and HFC-365/227 (93 wt% pentafluorobutane/7wt% heptafluoropropane). 

Additionally, the processing window for HFC-245fa foams does not appear to be radically more limited than HCFC-141b systems. Existing foam equipment should be capable of processing good-quality foam blown with the new agent,... 

Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks... 

In the study of HMSPP foaming blown by butane, Naguib, Park, and Reichelt (2004) discussed the effect of die temperature on volume expansion ratio and cell density of PP foams. The different optimum die temperature that produced the maximum expansion ratio was observed for the different gas content injection. For the cell density of PP foams, however, they did not change with the die temperature, which indicated the decreased die temperature did not induce the enhanced cell nucleation. In the case of PP/clay (Zhai et al., 2010), PP/silica (Zhai, Park, and Kontopoulou, 2011), and nanocomposites extrusion foaming, however, Zhai et al., (2010), found that the decreased die temperature not only increased the expansion ratio of PP foams but also increased their cell densities. This phenomenon resulted from the enhanced cell nucleation and the suppressed cell coalescence, and the mechanisms will be discussed in the next section. In addition, for PP nanocomposite foaming systems, a typical mountain shape of foam expansion relative to the die temperature was also observed. 

Zhai, W. T., T. Kuboki, L. Wang, C. B. Park, E. K. Lee, and H. E. Naguib. 2010. Cell structure evolution and the crystallization behavior of polypropylene/clay nanocomposites foams blown in continuous extrusion. Ind Eng Chem Res 49 9834-45. 

Zhai, W. T. andC. B. Park. 2011. Effect of nanoclay addition on the foaming behavior of linear PP-based soft TPO foam blown in continuous extrusion. Polym Eng Sci 51 2387-97. 

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