Preparation of Sound Absorption Material Based on Interpenetrating Polymer Network (PU/PMMA IPN)

Polymer composites with interpenetrated polymer network (IPN) structure are widely used as sound and vibration damping materials due to their high viscoelastic properties within the glass transition temperature range. In this study, polyurethane (PU)/poly (methyl methacrylate) (PMMA)-based interpenetrating polymer network with different ratios of PU to PMMA (i.e. 85:15, 75:25, and 65:35) were prepared by in situ polymerization. The properties of as-prepared IPN and its components were evaluated by different scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and sound absorption. Tensile properties were also determined. As indicators of effective damping capability, viscoelastic parameters including loss factor (tan δ), glass transition temperature (Tg), and effective damping interval (tan δ > 0.3) were also determined. In order to determine the sound absorption coefficient in the prepared IPNs, a two-microphone impedance tube at the frequency of one octave was used. The comparison of pure polymers (i.e. polyurethane and polymethyl methacrylate) and prepared IPNs indicated that the semi interpenetrated polymer network morphology was created through a broader range of tan δ in different IPNs. Incorporation of PMMA into polyurethane in the form of interpenetrating polymer networks enhanced the damping acoustic properties of the semi-IPNs due to the permeability of the two polymers. In the temperature range of -50 to 11 ˚C, both IPNs components showed high damping characteristics (tan δ ≥ 0.3). Evaluation of the results indicated that the blends are capable of exerting viscoelastic effects for damping and sound attenuation.