Synchronous Improvement of Mechanical and Room-Temperature Damping Performance in Light-Weight Polyurethane Composites by a Simple Carbon-Coating Strategy

Abstract

In order to address vibration and noise challenges in modern industry while satisfying the lightweighting requirements for aerospace and transportation applications, the development of polymer elastomers integrating both lightweight and high-damping properties holds substantial significance. This study developed polyurethane (PU) with optimized damping and mechanical properties at room temperature through monomer composition optimization. Hollow glass microspheres (HGMs) were introduced into the PU matrix to increase stiffness and reduce density, though this resulted in decreased tensile strength (Rm) and loss factor (tanδ). To further improve mechanical and damping properties, we applied a carbon coating to the surface of the HGMs to optimize the interface between the HGMs and the PU matrix, and systematically investigated the energy dissipation and load-bearing behavior of PU composites. The effect of enhanced interface damping of HGM@C/PU resulted in broadening of the effective damping temperature range (tanδ ≥ 0.3) and higher maximum loss factor (tanδ_max) compared to HGM/PU at equivalent filler loading. The tensile and dynamic properties significantly improved due to optimized interfacial adhesion. In PU composites reinforced with 10 wt% HGM and HGM@C, a 46.8% improvement in Rm and 11.0% improvement in tanδ_max occurred after carbon coating. According to acoustic testing, average transmission loss of HGM/PU and HGM@C/PU with the same filler content showed a difference of 0.3-0.5 dB in 500-6300 Hz, confirming that the hollow structure of the HGMs was preserved during carbon coating.

Keywords: carbon coating; damping properties; interface damping; mechanical properties; polyurethane elastomers.

Figure 1

Synthesis of (a) PU elastomer; (b) HGM@C and HGM@C/PU composites.

Figure 2

(a) FTIR spectrum; (b) DMA loss factor (tanδ) curves; (c) DMA storage modulus (E’) curves; (d) typical stress–strain curves; (e) tensile strength (Rm) and elongation at break (At) of PU₂₀₀₀-5.5, PU₁₀₀₀-5.5, and PU₆₅₀-5.5.

Figure 3

(a) FTIR spectrum; (b) DMA loss factor (tanδ) curves; (c) DMA storage modulus (E’) curves; (d) typical stress–strain curves; (e) tensile strength and elongation at break of PU₆₅₀-5.5, PU₆₅₀-7, and PU₆₅₀-8.5.

Figure 4

(a) FTIR spectrum; (b) DMA loss factor (tanδ) curves; (c) DMA storage modulus (E’) curves; (d) stress–strain curves; (e) tensile strength and elongation at break of PU₆₅₀-7, PU₆₅₀-7(6/9), PU₆₅₀-7(2/9), and PU₆₅₀-7(0/9).

Figure 5

SEM images of (a) original HGMs; (b) carbon coated HGMs; (c) the surface of HGM@C; (d) XRD patterns of HGMs under different heat treatment temperatures; (e) FTIR spectrum; (f) Raman spectrum; (g) XPS spectra of HGM@C; high-resolution XPS spectra of (h) C 1s; (i) N 1s of HGM@C.

Figure 6

(a–d) Fracture surface of pure PU, PU-5C, PU-10C, and PU-15C in liquid nitrogen; (e,f) fillers debonding in tensile fracture surface of PU-10 and PU-10C composites.

Figure 7

(a) FTIR spectrum; (b) XRD spectrum; (c,d) TG and DTG curves of PU composites.

Figure 8

(a) Tensile stress–strain curves; (b) tensile strength; (c) elongation at break; (d) Shore A hardness of PU composites.

Figure 9

Compressed hysteresis loop stress–strain curves of (a) HGM/PU; (b) HGM@C/PU composites with strain of 10%; (c) compressed stress–strain curves of PU composites; (d) compression modulus of HGM/PU and HGM@C/PU composites.

Figure 10

(a) Loss factor-temperature curves; (b) storage modulus-temperature curves; (c) DMA extrapolation curve, and (d) segment activation energy of PU composites derived from the Muller and Huff equations.

Figure 11

(a) Sound insulation curves of PU composites; (b) average transmission loss and density of PU composites.