Cellulose Nanocrystals as a Filler for Automotive Acrylic Paint: From Structural Characterization to Acoustic Attenuation

Abstract

Cellulose Nanocrystals (CNCs) have emerged as a sustainable bio-based nanomaterial with potential applications as a filler in polymer coatings. For this reason, the present study aimed to extract CNC from commercial microcrystalline cellulose (MCC) and evaluate its effect on structural, optical, moisture uptake, and acoustic attenuation properties of an automotive acrylic paint. CNC was extracted by alkaline peroxide pretreatment followed by acid hydrolysis and analyzed by Raman spectroscopy, X-ray diffraction (XRD), scanning electron and transmission microscopies (SEM and TEM), dynamic light scattering (DLS), and confocal laser scanning microscopy (CLSM). CNCs exhibited a rod-like morphology from 100 to 356 nm and high crystallinity (63%). CLSM analyses demonstrated qualitative evidence of CNC distribution in the acrylic matrix. A relative water uptake study showed that low CNC contents slightly improved barrier properties, whereas those higher increased moisture absorption due to their hydrophilic nature. Acoustic testing indicated enhanced preliminary acoustic attenuation with increasing CNC content, evidenced by lower minimum pressure values. These results provide preliminary evidence that CNCs can serve as a bio-based filler for acrylic coating systems with potential relevance to automotive applications.