A hydrophobic coating on cellulose nanocrystals improves the mechanical properties of polyamide-6 nanocomposites

Abstract

Recent demands for high-performance lightweight materials have brought researchers’ attention to various nanoparticles to reinforce polymeric materials. As such, sustainable and stiff cellulose nanocrystals (CNC) have become a popular candidate as nano-reinforcements. While CNC can offer great advantages, such as high mechanical properties and low density, it might agglomerate even in hydrophilic polymers because of its strong affinity to itself (intra and intermolecular hydrogen bonds) which prevents its broader use in industrial applications. This study aims to improve the compatibility between CNC and polyamide 6 (PA6) by a chemical modification that produces a surface polarity drastically different from non-modified CNC. The surface of CNC was rendered by the covalent coupling of stearic acid (SA) to the surface hydroxyl groups to produce stearate modified CNC (CNC SA). The effect of the modification was analyzed for CNC SA reinforced PA6 nanocomposites, and the results are compared to that of non-modified CNC reinforced PA6 samples. The addition of unmodified CNC to PA6 provided a modest improvement while the addition of CNC-SA provided substantial improvement on the modulus and tensile strength of the nanocomposite films.

Erimiş Filament Üretim Yöntemi ile Üretilen Kompozit Yapılarda Yöne Bağlı Yüzey Özelliklerinin İncelenmesi ve İyileştirilmesi

“…Formic acid, CH2O2 (98%+ pure), was obtained from ACROS Organics and used in liquid form. Many studies have reported that formic acid has a corrosive effect on polyamide [21]. For this reason, it is preferred for surface modification.…”

“…The effect of the printing direction on the surface roughness for flat samples was examined on the X-Y plane, and for on-edge samples, the effect of layer thickness was examined on the Z-axis. 239 literature knowledge literature [24][25][26][27], formic acid was preferred, and these stated processing values were selected in this study because it was observed to have a corrosive effect on polyamide material.…”

Significant Improvement of Thermal Conductivity of Polyamide 6/Boron Nitride Composites by Adding a Small Amount of Stearic Acid

“…When the SA content is high, some SA molecules will be excluded to the interface between PA6 and BN, leading to the improvement of the compatibility between PA6 and BN. Therefore, SA was often used in PA6 composites to promote the compatibility between PA6 and fillers [44]. In this work, when the SA content is less than 3 phr, it is mainly distributed in the PA6 phase.…”