Effects of Amino-Functionalized Graphene Oxide on the Mechanical and Thermal Properties of Polyoxymethylene

Use of synthetic wollastonite nanofibers in enhancing mechanical, thermal, and flammability properties of polyoxymethylene nanocomposites

This study investigates the mechanical, thermal, and flammability properties of synthetic wollastonite nanofibers (SWN) reinforced polyoxymethylene (POM) nanocomposites. SWN has been added into the POM nanocomposites in the range of 0.5–3 phr via melt blending. The mechanical properties were investigated through tensile and impact tests with scanning electron microscopy and energy dispersive X‐ray analysis. The thermal characterization was performed by thermogravimetry analysis and differential scanning calorimetry. Flame retardancy of nanocomposites was studied through cone calorimetry analysis and limiting oxygen index test. The tensile strength of nanocomposites improved by 5.88% at 1 phr SWN content, whereas Young's modulus increased with increasing content. The thermal stability of nanocomposites was enhanced as indicated by the higher initial degradation temperature, which rose about 22°C at 1 phr SWN content. The POM/SWN nanocomposites exhibited better mechanical strength despite their lower crystallinity due to the substantial reinforcing effect of SWN. The flame retardancy of nanocomposites improved, as indicated by the reduction of peak heat release rate from the cone calorimetry test. This study shows that SWN has simultaneously enhanced the mechanical strength, thermal stability, and flame retardancy of POM nanocomposites and has the potential in automotive applications.

Mechanical Reinforcement in Nylon 6 Nanocomposite Fiber Incorporated with Dopamine Reduced Graphene Oxide

The emergence of graphene-based polymer composite fibers provides a new opportunity to study the high-performance and functional chemical fibers. In this work, we have developed an efficient and convenient method with polydopamine (PDA) to functionalize and reduce graphene oxide (GO) simultaneously, and the modified graphene nanosheets can obtain uniform dispersion and strong interfacial bonding in nylon 6 (PA6). Furthermore, the reinforced PA6 composite fibers were prepared through mixing PDA-rGO into the PA6 polymer matrix and then melt spinning. The functional modification was characterized by surface analysis and structural testing including SEM, TEM, FTIR, and Raman. When the addition amount of the modified GO was 0.15 wt%, the tensile strength and Young’s modulus of the composite fiber reached 310.4 MPa and 462.3 MPa, respectively. The results showed a meaningful reinforcement with an effect compared to the pure nylon 6 fiber. Moreover, the composite fiber also exhibited an improved crystallinity and thermal stability, as measured by DSC and TGA.

Synergistic antibacterial effect of tetracycline hydrochloride loaded functionalized graphene oxide nanostructures

With the high demand for developing novel composites with integrated performance, graphene-based nanostructures have been drawing great attention in environmental and biomedical applications because of their extraordinary physicochemical properties and biocompatibility. Although graphene oxide (GO) nanosheets exhibit some antibacterial activities, novel GO based nanostructures with enhanced antibacterial activities are highly desired. To realize this aim, polyethyleneimine (PEI) modified GO as a tetracycline hydrochloride (TCH) carrier and release platform was constructed (pGO-TCH). The nanostructures were fully characterized by TEM, AFM, FTIR and Raman spectra, which demonstrated that TCH were uniformly and compactly deposited on PEI modified GO nanosheets. The antibacterial performances of the prepared nanostructures were investigated by disk diffusion method and bacterial growth kinetics method towards Gram-positive S. aureus and Gram-negative E. coli. Results show that pGO-TCH nanostructures exhibit good antibacterial behavior. The mechanism of antibacterial activity was studied. Moreover, the nanostructures showed good cytocompatibility. This study not only highlights a promising pGO-TCH nanostructure as a candidate of graphene-based antibacterial agent, but also provides us antibacterial mechanism between bacteria and graphene-based nanomaterials.