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Water-borne styrene-acrylate networks with tunable acoustic performance
Researchers from Iran have developed water-borne styrene-acrylate systems with adjustable damping and sound absorption properties. The materials are based on interpenetrating polymer networks featuring a core-shell structure.
A team led by Seyed Mohammadsadegh Jafari Alavi has explored how the mechanical and acoustic properties of styrene-acrylate binders can be fine-tuned through polymer design. The researchers synthesised latex-based interpenetrating polymer networks (LIPNs) via multi-stage emulsion polymerisation and studied the effects of shell feeding, core monomer composition, crosslinker ratio and methyl methacrylate (MMA) content in the shell.
FTIR spectra confirmed the formation of a network within the particle core. The latex particles showed a narrow size distribution between 150 and 185 nm and zeta potentials ranging from −56 to −30 mV, indicating good stability. The addition of 1 wt% crosslinker improved particle stability, while higher concentrations (3 and 5 wt%) reduced it. SEM and TEM analyses confirmed spherical morphology with complete shell coverage.
Reading tip: water-based acrylic dispersions
Water-based polyacrylates, as emulsion binders, dispersing resins or thickening polymers, are nowadays impossible to do without as raw materials in the paint and coatings industry. In its second, updated edition “Water-based Acrylic Dispersions” offers a clear and comprehensive overview of everything one needs to know about the various types of binders, systems and test methods associated with the application of water-based acrylic dispersions in architectural coating systems. Essential for novices to the technology or those switching specialisms, along with students and experts who wish to expand and deepen their knowledge about the formulation and testing of water-based acrylic dispersions.
Correlation between mechanical strength and sound absorption
Tensile testing demonstrated that increasing the MMA content in the shell enhanced tensile strength from 0.2 MPa at 0 wt% MMA to 4.6 MPa at 42 wt%. Similarly, adding 5 wt% crosslinker to the core increased tensile strength from 3.3 MPa to 7.3 MPa.
Dynamic mechanical thermal analysis (DMTA) and impedance tube measurements were used to evaluate damping and acoustic performance. A strong correlation between experimental and theoretical sound absorption values was found at 2000 Hz. To describe this relationship, the authors proposed a linear model linking mechanical damping (TAeffect) to sound absorption (NRC), achieving an excellent correlation coefficient of R² = 0.97.
