Structure and properties of PA6-66/γ-aminopropyltriethoxysilane-modified clay nanocomposites prepared by in situ polymerization

Abstract

In this study, PA6-66/γ-aminopropyltriethoxysilane-modified clay nanocomposites were prepared byin situpolymerization. It was found that the γ-aminopropyltriethoxysilane was chemically grafted onto clay successfully, and the covalent bond was formed between the clay and polymer chains. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) results indicated that intercalated and exfoliated nanocomposites were obtained. The PA6-66 nanocomposites exhibited improved mechanical performance compared to that of neat PA6-66. Most importantly, the PA6-66 nanocomposites showed significantly improved toughness. In comparison with neat PA6-66, the rupture stress and elongation at the break of the nanocomposite with only 0.5 wt% clay increased 91.9% and 91.8%, respectively. The excellent toughness of PA6-66 nanocomposites should be mainly ascribed to the combined effects of strong polymer-clay interaction, the intercalated-exfoliated structures of clay, refined crystalline, formation of γ-form crystals, and decreased crystallinity of PA6-66.

Comparative Screening of the Structural and Thermomechanical Properties of FDM Filaments Comprising Thermoplastics Loaded with Cellulose, Carbon and Glass Fibers

“…where ∆H m1 and ∆H m2 represent the melting enthalpy of the crystals formed in the polymer during the first and second heating cycle, respectively, and ∆H cc1 is the enthalpy of cold crystallization formed during first heating. ∆H • m is the theoretical enthalpy value for a 100% crystalline polymer as follows: PLA = 93.7 J/g [30]; PA6 = 230 J/g [31]; PA6/66 = 240 J/g [32]; PET = 130 J/g [27] and wt% filler is the mass fraction of fillers present in the filament. X c1F is the initial existing crystallinity of the printing filament and X c13D is considered as the overall crystallinity of 3D printed part evolved after 3D printing (from first heating cycle).…”

“…For PA6/66, two melting peaks (T m1 and T m2 ) were observed comparing the single peak for GF-PA6 and was attributed to the presence of PA6 and PA66 polymer with different melting points. A copolymer of PA6 with a fraction of PA66 is favored for 3D printing application, as it leads to a decrease in melting point and crystallization, enhances clarity and comprehensive mechanical properties, it also reduces the average material cost [32]. The copolymer filament of PA6/66 used in this study was blended in a ratio of 80:20, as determined from the very similar thermal properties (T m1 , T m2 and T mc ) of PA6/66 mentioned in the literature [32].…”

“…A copolymer of PA6 with a fraction of PA66 is favored for 3D printing application, as it leads to a decrease in melting point and crystallization, enhances clarity and comprehensive mechanical properties, it also reduces the average material cost [32]. The copolymer filament of PA6/66 used in this study was blended in a ratio of 80:20, as determined from the very similar thermal properties (T m1 , T m2 and T mc ) of PA6/66 mentioned in the literature [32]. In contrast to PLA and its composites, a significant difference was observed in the glass transition temperature of PA6/66 and GF-PA6 from the first and second heating cycle (T g(i) and T g(ii) , Table 3).…”