• Transactions of Materials Processing
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• v.11 no.1
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• pp.69-74
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• 2002

In addition to lightweight and moldable characteristics, polymeric foams possess an excellent energy absorbing capability that can be utilize for a wide range of commercial applications, especially in the crashworthiness of the automobiles. The purpose of the present study is to develop experimental methodology to characterize the pressure dependent yield behavior of the energy absorbing polymeric foams. For the compression test in a triaxial stress sate, a specially designed device was placed in a hydraulic press to produce and control oil pressure. For the test material, the polyurethane foams of two different densities were used. The displacement of the specimen, the load subjected to the specimen, and oil pressure applied to the specimen were measured and controlled. Stress strain curves and yield stresses for the four different oil pressure were obtained. It was found from the present experiments that the polyurethane foams exhibited significant increases in yield stress with applied pressure or mean normal stress. Based on this observation, a yield criteria which included the effect of the stress invariant were established for the polymeric foams. The obtained experimental constants which constituted the pressure-dependent yield criterion were verified.

• Carbon letters
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• v.13 no.2
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• pp.94-98
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• 2012

Herein, macroporous carbon foams were successfully prepared with phenol and formaldehyde as carbon precursors and an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ($BMIPF_6$), as a pore generator by employing a polymerization-induced phase separation method. During the polycondensation reaction of phenol and formaldehyde, $BMIPF_6$ forms a clustered structure which in turn yields macropores upon carbonization. The morphology, pore structure, electrical conductivity of carbon foams were investigated in terms of the amount of the ionic liquid. The as-prepared macroporous carbon foams had around 100-150 ${\mu}m$-sized pores. More importantly, the electrical conductivity of the carbon foams was linearly improved by the addition of $BMIPF_6$. To the best of the author's knowledge, this is the first result reporting the possibility of the use of an ionic liquid to prepare porous carbon materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1398-1401
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• 2003

Recently, The PolyPropylene(PP) Foam used as Bumper and Helmet is well known as a protective material for products. In this paper, the effect of the density of PP foams on the absorption of the impact energy is implemented. The result of the experiment has revealed that the effect of the high-density PP foams is remarkably increased compared with that of the low-density PP foams. And it also shows that the absorption of the impact energy of PP foams are greatly influenced by the density in impact velocity(220cm/s). These results are expected to be utilized for the technique of manufacturing a optimum impact structure.

• Textile Coloration and Finishing
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• v.17 no.6 s.85
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• pp.36-41
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• 2005

The effects of low temperature plasma treatment on the properties of three types of foams, polyurethane(PU), injection phylon(IP), and phylon(PH) that used for footwear mid-sole were examined. The change of surface properties of foams were characterized by electron scanning microscope, contact angle measurement, and universal testing machine. Adhesion was tested by T-peel tests of plasma treated foams/polyurethane adhesive joints. The contact angle of three types of foams were decreased dramatically with the plasma treatment time, specifically noticeable in the case of phylon(Ph). It has shown the relationship with the contact angle of phylon(PH) and the distance between electrode and samples. The peel strength of foams were increased with the increase of plasma treatment time.

• Elastomers and Composites
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• v.39 no.3
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• pp.186-192
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• 2004

Compression and rebounding properties of IP(injection phylon), PH(phylon) and PU(polyurethane) foams were studied. The compression stress, rebounding stress, loss compression energy and storage compression energy of foams were decreased with increasing hardness of foams. The compression stress, loss compression energy of IP foams were lower than those of PH and PU. Rebounding stress and storage compression energy of PU foams were higher than those of IP and PH. The compression stress and rebounding of PH foam were lower than those of IP and PU.

• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

• Journal of Korea Foundry Society
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• v.31 no.3
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• pp.145-151
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• 2011

Metallic foam has been known as a functional material which can be used for absorption properties of energy and sound. The unique characteristics of Al foam of mechanical, acoustic, thermal properties depend on density, cell size distribution and cell size, and these characteristics expected to apply industry field. Al-Zn-Mg-Cu alloy foams was fabricated by following process; firstly melting the Al alloy, thickening process of addition of Ca granule to increased of viscosity, foaming process of addition of titanium hydride powder to make the pores, holding in the furnace to form of cooling down to the room temperature. Metal foams with various porosity level were manufactured by change the foaming temperature. Compressive strength of the Al alloy foams was 2 times higher at 88% porosity and 1.2 times higher at 92% porosity than pure Al foams. It's sound and vibration absorption coefficient were higher than pure Al foams and with increasing porosity.

• Elastomers and Composites
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• v.40 no.4
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• pp.242-248
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• 2005

To study the fatigue properties of three type of foams for footwear midsole, polyurethane(PU), phylon(PH) and injection phylon(IP) foams were prepared with different hardnesses. Three types of foams were repetitively compressed for 50,000 cycles at 50 rpm. Cell shapes of foams were deformed with repetitive compression. The extent of cell deformation of IP was larger than those of PH and PU. Permanent strain of foam was made by repetitively compressing the foam, and the extent of IP was larger than those of PU and PH. Maximum compression forces of three types of the foams were decreased with the repetitive compression, and IP had the largest decrease in compression load of foam with compression. Decreases in maximum compression force of three types of foams were increased with increase of the hardness of foam.

• Elastomers and Composites
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• v.39 no.4
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• pp.274-280
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• 2004

Sorage modulus(G'), Impact and rebounding properties of polyurethane(PU), phylon(PH) and injection phylon(IP) foams were studied. The storage modulus of PU foam was dramatically increased with decreasing temperature. But the storage modulus(G') of IP and PH foams were not affected by temperature. The Impact force of PU foams was increased with decreasing temperature. But in the cases of IP and PH foams, the impact forces were not changed with temperature below $20^{\circ}C$. Impact farces of IP and PH foams were increased with the temperature above $20^{\circ}C$, but that of PU foam was not changed. Rebounding resilience of PU foam was lower than those of IP and PH foams from $-20^{\circ}C$ to $40^{\circ}C$.

• Fire Science and Engineering
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• v.14 no.2
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• pp.7-13
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• 2000

We had investigated thermal stability, Ignition temperature and fire gas for polyurethane foams used for manikin, cushion and interior finishing material. Decomposition of polyurethane foams with temperature was investigated using a DSC and the weight loss with temperature increase using a TGA in order to find the thermal hazard of polyurethane foams, and the ignition temperature of polyurethane foams according to species. We studied constant temperature among ignition temperature measuring methods. In addition, noxious gases for polyurethane foams according to combustion condition were analyzed using gas analyzer and GASTEC. As results, initial decomposition temperature of polyurethane foam used for interior finishing material was lower than those for manikin and cushion, and exothermic energy was higher. Ignition temperature of polyurethane foam of interior finishing material was $420^{\circ}$. All of combustion forms at $427^{\circ}$ and under were smoldering combustion, and it was combustion at $500^{\circ}$. As furnace temperature was increased, concentration of noxious gases such as carbon oxide, carbon dioxide, and hydrogen cyanide was increased. And nitrogen oxide at combustion condition($500^{\circ}$) was over 10 ppm.