Nanoparticles Filled Polymer Composites Research Articles

Improving piezoelectric performance of lead-free polymer composites with high aspect ratio BaTiO3 nanowires

Flexible and lead-free piezoelectric nanocomposites were synthesized with BaTiO3 nanowires (filler) and poly(vinylidene fluoride) (PVDF) (matrix), and the piezoelectric performances of the composites were systematically studied by varying the aspect ratio (AR) and volume fraction of the nanowire and poling time. BaTiO3 nanowires with AR of 18 were synthesized and incorporated into PVDF to improve the piezoelectric performance of the composites. It was found that high AR significantly increased the dielectric constant up to 64, which is over 800% improvement compared to those from the composites containing spheroid shape BaTiO3 nanoparticles. In addition, the dielectric constant and piezoelectric coefficient were also enhanced by increasing the concentration of BaTiO3 nanowires. The piezoelectric coefficient with 50-vol% BaTiO3 nanowires embedded in PVDF displayed 61 pC/N, which is much higher than nanocomposites with spheroid shape BaTiO3 nanoparticles as well as comparable to, if not better, other nanoparticle-filled polymer composites. Our results suggest that it is possible to fabricate nanocomposites with proper mechanical and piezoelectric properties by utilizing proper AR fillers.

Preparation of UV-Curable Nanocomposite Varnish with High Wear Resistance

To enhance the interfacial interaction in silica nanoparticles filled polymer composites , nano-SiO2 gel was prepared by a sol-gel route, and then it was modified in situ through a reaction of silane coupling agent with hydroxyl on the surface of SiO2. The modified nano-SiO2 gel was added to the system of light-cured varnish to prepare UV light-cured nanocomposite varnish. The structures and properties of varnish were studied using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and film performance test. The results showed that the modified nano-SiO2 was well dispersed in the varnish. After introduction of modified nano-SiO2, the fracture morphology of varnish film showed a corrugated shape, indicating the ductile fracture. The wear resistance of the varnish film increased by 50%, the coefficient of static friction reduced about 15%, and gloss improved to some extent.

Effect of Injection Molding Process on Electrical Conductivity and Mechanical Property of Nanoparticle Filled Polymer Composites

Authors investigated the relationship among processing parameters, microstructures, electrical conductivity and mechanical property of injection molded nanoparticle filled polymer composites at present study. Standard tensile specimens were injected under different injecting pressures and packing pressures. The molded specimens were removing five layers from the surface to observe the microstructures at different positions of the moldings. The electrical properties were measured with a two-terminal standard resistor under DC condition at room temperature, and the mechanical properties of the moldings were measured by INSTRON 5580 Universal testing machine. The results showed that filled nanoparticles may form the best conductive path under the higher packing pressure matched with higher injection pressure. The mechanical properties of the molding depend on not only the concentration of the nanofiller, but processing conditions as well.

Preparation and characterization of UV-curable epoxy/silica nanocomposite coatings

To enhance the interfacial interaction in silica nanoparticles filled polymer composites, the silica surface was firstly treated with glycidoxypropyl trimethoxysilane (GPTMS), and its structure was analyzed by 13C NMR and FTIR spectrophotometry. Then a series of GPTMS-modified silica/cycloaliphatic epoxy nanocomposite coatings with 0–6 wt% silica content were prepared by UV-induced cationic polymerization in the presence of a diaryliodonium photoinitiator and thioxanthone photosensitizer. The physical and mechanical properties such as hardness, adhesion, gloss, impact as well as tensile strength were examined. As a result, these composites demonstrated superior tensile strength and tensile modulus with increasing proportion of modified silica up to a certain level. An increase in abrasion resistance of nanocomposites with the addition of modified silica was observed. The thermal stability of nanocomposites was not enhanced with the addition of silica particles. SEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.

Performance Improvement of Nano-silica/Polypropylene Composites through in-situ Graft Modification of Nanoparticles during Melt Compounding

AbstractTo prepare inorganic nanoparticles filled polymer composites, reactive monomer was added to the ingredients prior to manufacturing. The results showed that in-situ graft polymerization of butyl acrylate onto nano-silica occurred during melt compounding with polypropylene matrix. As a result, dispersion of the grafted nanoparticles in the polymer became much more homogeneous than in the case of untreated version, and filler/matrix interaction was enhanced due to the intimate adhesion among the components. Both tensile performance and impact toughness of the composites were improved at rather low filler loading. Compared to the twostep approach developed in our lab, by which nanoparticles are treated by graft polymerization firstly and then mixed with polymer melt, the current one-step method is simpler and able to provide the composites with much higher notched impact resistance.

Polymer Nanocomposites with Fullerene‐like Solid Lubricant

Recent experiments showed that the addition of inorganic fullerene‐like (IF) WS2 or MoS2 solid lubricant nanoparticles in oil, grease or impregnated into porous matrix provides remarkable lubricating properties of friction pairs in a wide range of operating conditions. Inorganic nanoparticles filled polymer composites show low friction and high wear resistance. This work reports the first attempt to fill polymers with hollow solid lubricant nanoparticles. It was found that application of the IF solid lubricant nanoparticles leads to a considerable improvements in the tribological behavior of the nanocomposites. The morphology of the surface layers and the mechanism of the friction reduction by the IF nanoparticles are discussed.

Surface modification of magnetic metal nanoparticles through irradiation graft polymerization

To tailor the interfacial interaction in magnetic metal nanoparticles filled polymer composites, the surfaces of iron, cobalt and nickel nanoparticles were grafted by irradiation polymerization. In the current report, effects of grafting conditions, including irradiation atmosphere, irradiation dose and monomer concentration, on the grafting reaction are presented. The interaction between the nanoparticles and the grafted polymer was studied by thermal analysis and X-ray photoelectron spectrometry. It was found that there is a strong interfacial interaction in the form of electrostatic bonding in the polymer-grafted nanoparticles. The dispersibility of the modified nanoparticles in chloroform was significantly improved due to the increased hydrophobicity.

Graft polymerization of vinyl monomers onto nanosized alumina particles

To enhance the interfacial interaction in alumina nanoparticles filled polymer composites, an effective surface modification method was developed by grafting polystyrene and polyacrylamide onto the particles. That is, the alumina surface was firstly treated with silane, followed by radical grafting polymerization in aqueous or non-aqueous systems. Results of infrared spectroscopy and dispersiveness in solvents demonstrated that the desired polymer chains have been covalently bonded to the surface of the alumina particles. They also greatly changed their surface characteristics. In addition, effects of polymerization conditions, including ways of monomer feeding, concentrations of monomer and initiator, and reaction time, on the grafting reaction were presented. It was found that the growing polymer radicals and/or the grafted polymer chains had a blocking effect on the diffusion of radicals or monomers towards the surface of nanoalumina. This was due to the fact that the interaction between the solvent and the grafted polymers was weaker than that between the grafted polymers and the nanoparticles. 2002 Elsevier Science Ltd. All rights reserved.