Functional Hollow Ceramic Microsphere/Flexible Polyurethane Foam Composites with a Cell Structure: Mechanical Property and Sound Absorptivity.

Jia-Horng Lin,Mei-Feng Lai,Po-Yang Hsu,Bing-Chiuan Shiu,Chen-Hung Huang,Ching-Wen Lou

doi:10.3390/polym14050913

Abstract

Noise pollution is the primary environmental issue that is increasingly deteriorated with the progress of modern industry and transportation; hence, the purpose of this study is to create flexible PU foam with mechanical properties and sound absorption. In this study, hollow ceramic microsphere (HCM) is used as the filler of polyurethane (PU) foam for mechanical reinforcement. The sound absorption efficacy of PU pores and the hollow attribute of HCM contribute to a synergistic sound absorption effect. HCM-filled PU foam is evaluated in terms of surface characteristic, mechanical properties, and sound absorption as related to the HCM content, determining the optimal functional flexible PU foam. The test results indicate that the presence of HCM strengthens the stability of the cell structure significantly. In addition, the synergistic effect can be proven by a 2.24 times greater mechanical strength and better sound absorption. Specifically, with more HCM, the flexible PU foam exhibits significantly improved sound absorption in high frequencies, suggesting that this study successfully generates functional PU foam with high mechanical properties and high sound absorption.

Highlights

Noise pollution is of the major pollutions in the environment and increasingly escalating with the progress of industries and transportation
PU foam can be classified into rigid polyurethane foam (RPUF) and flexible polyurethane foam (FPUF)
The surface observation, mechanical properties, and sound absorption measurements were conducted in order to obtain the optimal hollow ceramic microsphere (HCM)/FPUF sound absorbent composites

Summary

Introduction

Noise pollution is of the major pollutions in the environment and increasingly escalating with the progress of industries and transportation. The main mechanism to reduce noise pollution involves a rise in abrasion against air molecules, as well as the damping of absorbent materials. The sound absorption frequency is the main concern for the design of sound absorbing materials. The damping can absorb the sound or delay the transmission of sound, during which the acoustic energy is transformed into thermal energy, thereby achieving effective sound absorption and noise abatement [2]. Polyurethane (PU) elastomer has been the most frequently used industrial polymer [3], so PU made of isocynate and polyol is the most popular material used in the construction, automobile, sports, navy, and furniture fields [4–7]. Composed of more polyol than RPUF, FPUF demonstrates greater flexibility, which means that FPUF outperforms RPUF in withstanding a high deformation. FPUF possesses excellent physical properties and cushioning effect, so it is pervasively used in different regions; e.g., furniture, carpet, and vehicles [8,9]

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