Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
New Bio-Based Polyurethane Foam with Alumina Trihydrate: Sound Transmission Loss Properties
Submission Author:
Enio Henrique Pires da Silva , PR , Brazil
Co-Authors:
Enio Henrique Pires da Silva, Guilherme Waldow, Guilherme Irigoyen Bueno, Romeu Rony Cavalcante da Costa, Ricardo De Medeiros, Volnei Tita, Marcelo Leite Ribeiro
Presenter: Enio Henrique Pires da Silva
doi://10.26678/ABCM.COBEM2021.COB2021-0946
Abstract
Rigid polyurethane foams (PUFs) are among the most consumed polymeric materials worldwide. They show a varied range of applications, such as insulation, furniture and automobile industry. The main concerns regarding PUF application are its high flammability and oil-based raw materials. Those are the reasons for the recent increasing demand over new bio-based PUFs and mechanisms for decreasing their flammability without harming their properties and ecological friendly appeal. Aluminum hydroxide (ATH) is a halogen-free non-toxic additive flame retardant that perfectly suits the needs mentioned earlier. Therefore, in this study, a bio-based PUF was synthesized with a 1.2/1 (isocyanate/green-polyol) ratio with the addition of 10%, 20%, 30%, 40%, and 50% of ATH mass fraction in order to evaluate the different responses in the sound transmission loss (TL) as ATH was added inside the PUF matrix. The TL tests were carried out in two impedance tubes manufactured by Brüel & Kjær, model 4206-T. These two tubes are in accordance with the ASTM E2611 standard, which defines the methodology for TL tests in frequencies prior and after the resonance region. Therefore, the test required specimens with two different diameters, 100 mm and 29 mm, to fit the low and high frequency tubes respectively. The specimens were polymerized inside a mold designed specifically for these tests, therefore the samples showed good dimensional standardization. The TL test results showed an increasing number for the stiffness sensitive region (100 mm tube) as the amount of ATH increased, going from 34.7±1.6 dB and 14.5±4.5 dB at 500 Hz and 1000 Hz respectively, for the pure PUF, up to 41.9±0.4 dB and 25.0±1.1 for the 50% ATH added foam. This result was acceptable since the stiffness of the polymer should increase with the addition of the ceramic flame retardant, moreover, the amount of ATH that exhibited these numbers is high enough to provide good fire extinguishment properties. At higher frequencies (29 mm tube), where the TL numbers are sensitive to mass, the samples also showed better results as the amount of ATH increased, going from 58.7±1.6 dB and 47.3±2.1 dB at 1000 Hz and 5000 Hz respectively, for the pure PUF, up to 61.9±1.2 dB and 50.0±2.4 for the 50% ATH added foam at the same frequencies. Therefore, the addition of ATH would increase the flame resistance of the polymeric foam as well as decrease the intensity of the sound waves crossing the material.
Keywords
Composite Materials, Cellular Materials, Polyurethane foam, Sound Transmission Loss
