Abstract
The application area of a sound insulation material is highly dependent on the technology adopted for its processing. In this study, thermoplastic rubber (TPR, polypropylene/ethylene propylene diene monomer) composites were simply prepared via an extrusion method. Two microscale particles, CaCO3 and hollow glass microspheres (HGW) were chosen to not only enhance the sound insulation but also reinforced the mechanical properties. Meanwhile, the processing capability of composites was confirmed. SEM images showed that the CaCO3 was uniformly dispersed in TPR matrix with ~3 μm scale aggregates, while the HGM was slightly aggregated to ~13 μm scale. The heterogeneous dispersion of micro-scale fillers strongly affected the sound transmission loss (STL) value of composites. The STL values of TPR composites with 40 wt % CaCO3 and 20 wt % HGM composites were about 12 dB and 7 dB higher than that of pure TPR sample, respectively. The improved sound insulation performances of the composites have been attributed to the enhanced reflection and dissipate sound energy in the heterogeneous composite. Moreover, the mechanical properties were also enhanced. The discontinued sound impedance and reinforced stiffness were considered as crucial for the sound insulation.
Highlights
Nowadays, noise pollution becomes much more serious with the rapid development of industry and transportation
The morphology of pure thermoplastic rubber (TPR), the inorganic fillers and the dispersion of inorganic particles in the composites were characterized by using a scanning electron microscopy (SEM type S-4700, JEOL, Akishima-shi, Japan)
In order to verify the exact dispersion of inorganic fillers, the fracture surface of TPR composites were etched by hydrochloride acid (10 wt %)
Summary
Noise pollution becomes much more serious with the rapid development of industry and transportation. Polymeric materials with micro/nano-structures have attracted increasing interest from both academic and industrial field. Hierarchical scale structure design of polymeric materials is regarded as one of the important route to achieve outstanding performance [10,11,12]. To achieve outstanding sound-insulation property, many efforts were contributed for fabrication of hierarchical scale structure. Liang reported that polymer foams in a sandwich structure could enhance the soundproof property owing to the viscoelastic air cells and increased sound wave propagation routine [24]. It is prominent to produce excellent soundproof polymer composites with enhanced mechanical properties by means of common feasible processing technologies. For the sake of excellent damping property of TPR, we choose the polypropylene/ethylene propylene diene monomer (PP/EPDM) composite, compounding with micro-scale CaCO3 and HGM particles. The sound insulation of the composites were markedly enhanced especially in a range of 50–1500 Hz, the mechanical properties were simultaneously improved
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