Effects of Silicone Surfactant on the Properties of Open‐Cell Flexible Polyurethane Foams

Abstract

In this paper, the effects of silicone surfactant on the mechanical, thermal, and acoustical properties of flexible polyurethane foams are studied. At first, by introducing the reactions of the foam production and expressing the stoichiometric relationships, a method is provided to select the amounts of the basic compounds for getting the desirable properties. By knowing the OH number of polyol and the NCO content of isocyanate after selecting an amount of a blowing agent for the reaction, the quantity of each compound to produce the desirable foam can be found. Then different foams with various amounts of surfactant are produced. By preparing proper samples, the mechanical, thermal, nonacoustical, and acoustical properties of the foams are measured or calculated by using different instruments. The nonacoustical properties are obtained based on two distinct methods, i.e., a semiphenomenological method and an indirect method. The obtained properties are validated by comparing the calculated theoretical sound absorption coefficients with the measured ones. The results show that with a small increase of surfactant, the acoustical properties of foam samples improve by about 50% without any significant changes in other mechanical and thermal properties of the foams. This improvement results from the variations of reticulation rate and cell size. In addition, the initial desirable porosity and density considered in the stoichiometric relations are fairly achieved in produced samples. These results validate the accuracy of the stoichiometric relations.

Effects of multiwall carbon nanotube and perfluoroalkane additives on the sound absorption properties of flexible polyurethane foams

“…Figure 8 shows that the increase of a with increasing frequency begins at 300-400 Hz, until a starts to decrease at a frequency of 2,500-3,100 Hz for PUF with additives. This frequency range includes a collection of sounds available in urban and industrial applications [16]. For PUF with an PFA or HMDS content of 1.25 phr, a higher a was observed.…”

“…The values of a in Fig. 9 were averaged in the frequency ranges between 1,600 and 2,500 Hz, covering the sensitive frequency region of the human ear [16]. For the PUF with PFA and HMDS at contents of 0.25, 0.50, and 1.25 phr, the sound absorption of the PUF was higher than of PUF without additives.…”

“…Polyurethane foam (PUF) has been widely studied due to its various thermal insulating applications in building construction, liquefied natural gas storage tank and carrier formers, and refrigeration [1][2][3][4][5][6][7][8][9]. Another important application is as sound absorber in the design of automobiles, using the acoustic damping abilities of PUF [1,2,[10][11][12][13][14][15][16]. There are several different frequency ranges in a vehicle, some of which originate from the rotation of the engine at 5-50 Hz, and some result from the uneven surface of the road and transfer into the vehicle in the frequency range of 500-3,000 Hz [12].…”

“…PUF is known to be a good sound absorption material [1,2,[14][15][16][17], and two major mechanisms can be considered: First, sound energy may be absorbed by the friction between gas molecules that oscillate inside the cells of the PUF, converting kinetic energy into heat. In this case, the cell morphology is mainly responsible for the amount of sound energy absorbed [18,19].…”

“…Second, the possible mechanism involves the cell wall material, which can absorb sound by what is known as intrinsic damping, in which the sound waves propagate inside the material [12]. In this case, the major factor that affects the sound absorption is flow resistance, which is based on the measurement of airflow resistivity [16,20].…”