Tuning the properties of carbon fiber-reinforced poly (phenylene sulphide) laminates via incorporation of inorganic fullerene-like WS2 nanoparticles

Novel carbon fiber (CF)-reinforced poly(phenylene sulphide) (PPS) laminates incorporating inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles were prepared via melt-blending and hot-press processing. The influence of the IF-WS2 on the morphology, thermal, mechanical and tribological properties of PPS/CF composites was investigated. Efficient nanoparticle dispersion within the matrix was attained without using surfactants. A progressive rise in thermal stability was found with increasing IF-WS2 loading, as revealed by thermogravimetric analysis. The addition of low nanoparticle contents retarded the crystallization of the matrix, whereas concentrations equal or higher than 1.0 wt% increased both the crystallization temperature and degree of crystallinity compared to those of PPS/CF. Mechanical tests indicated that with only 1.0 wt% IF-WS2 the flexural modulus and strength of PPS/CF improved by 17 and 14%, respectively, without loss in toughness, ascribed to a synergistic effect between the two fillers. A significant enhancement in the storage modulus and glass transition temperature was also observed. Moreover, the wear rate and coefficient of friction strongly decreased, attributed to the lubricant role of the IF-WS2 combined with their reinforcing effect. These inorganic nanoparticles show great potential to improve the mechanical and tribological properties of conventional thermoplastic/CF composites for structural applications.

Inorganic hydrophobic coatings: Surfaces mimicking the nature

Added value products are being developed in ceramic industry. Different optical effects as bright metallic shine or new functionalities as hydrophobicity or bactericide characteristics are the new properties searched on the tiles. In this study, we prepare glassy coatings for tiles based on copper pigment by a conventional industrial process. The obtained coatings present different aesthetical aspects, including bright metallic aspect which confers a high decorative value to the tile. Furthermore, these metallic coatings present hydrophobic properties with contact angles with water as high as 115 degrees and also bactericide characteristics. Superficial microstructure and nanoparticles were found in the bactericide-hydrophobic samples, resembling the surface of hydrophobic leaf surfaces. This structure was formed by the crystallization of CuO nanoparticles as Tenorite due to the copper saturation of the glassy matrix at the surface of the coatings.

Mechanical and thermal behaviour of isotactic polypropylene reinforced with inorganic fullerene-like WS2 nanoparticles: Effect of filler loading and temperature

The thermal and mechanical behaviour of isotactic polypropylene (iPP) nanocomposites reinforced with different loadings of inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles was investigated. The IF-WS2 noticeably enhanced the polymer stiffness and strength, ascribed to their uniform dispersion, the formation of a large nanoparticle?matrix interface combined with a nucleating effect on iPP crystallization. Their reinforcement effect was more pronounced at high temperatures. However, a drop in ductility and toughness was found at higher IF-WS2 concentrations. The tensile behaviour of the nanocomposites was extremely sensitive to the strain rate and temperature, and their yield strength was properly described by the Eyring s equation. The activation energy increased while the activation volume decreased with increasing nanoparticle loading, indicating a reduction in polymer chain motion. The nanoparticles improved the thermomechanical properties of iPP: raised the glass transition and heat deflection temperatures while decreased the coefficient of thermal expansion. The nanocomposites also displayed superior flame retardancy with longer ignition time and reduced peak heat release rate. Further, a gradual rise in thermal conductivity was found with increasing IF-WS2 loading both in the glassy and rubbery states. The results presented herein highlight the benefits and high potential of using IF-nanoparticles for enhancing the thermomechanical properties of thermoplastic polymers compared to other nanoscale fillers.

Development of novel melt-processable biopolymer nanocomposites based on poly(L-lactic acid) and WS2 inorganic nanotubes.

The use of tungsten disulphide inorganic nanotubes (INT-WS2) offers the opportunity to produce novel and advanced biopolymer-based nanocomposite materials with excellent nanoparticle dispersion without the need for modifiers or surfactants via conventional melt blending. The study of the non-isothermal melt-crystallization kinetics provides a clear picture of the transformation of poly(L-lactic acid) (PLLA) molecules from the non-ordered to the ordered state. The overall crystallization rate, final crystallinity and subsequent melting behaviour of PLLA were controlled by both the incorporation of INT-WS2 and the variation of the cooling rate. In particular, it was shown that INT-WS2 exhibits much more prominent nucleation activity on the crystallization of PLLA than other specific nucleating agents or nano-sized fillers. These features may be advantageous for the enhancement of mechanical properties and process-ability of PLLA-based materials. PLLA/INT-WS2 nanocomposites can be employed as low cost biodegradable materials for many eco-friendly and medical applications, and the exceptional crystallization behaviour observed opens new perspectives for scale-up and broader applications.

Novel poly(3-hydroxybutyrate) nanocomposites containing WS2 inorganic nanotubes with improved thermal, mechanical and tribological properties

Poly(3-hydroxybutyrate) (PHB) nanocomposites containing environmentally-friendly tungsten disulphide inorganic nanotubes (INTeWS2) have been successfully prepared by a simple solution blending method. The dynamic and isothermal crystallization studies by differential scanning calorimetry (DSC) demonstrated that the INTeWS2 exhibits much more prominent nucleation activity on the crystallization of PHB than specific nucleating agents or other nanoscale fillers. Both crystallization rate and crystallinity significantly increase in the nanocomposites compared to neat PHB. These changes occur without modifying the crystalline structure of PHB in the nanocomposites, as shown by wide-angle X-ray diffraction (WAXS) and infrared/Raman spectroscopy. Other parameters such as the Avrami exponent, the equilibrium melting temperature, global rate constant and the fold surface free energy of PHB chains in the nanocomposites were obtained from the calorimetric data in order to determine the influence of the INTeWS2 filler. The addition of INTeWS2 remarkably influences the energetics and kinetics of nucleation and growth of PHB, reducing the fold surface free energy by up to 20%. Furthermore, these nanocomposites also show an improvement in both tribological and mechanical (hardness and modulus) properties with respect to pure PHB evidenced by friction and nanoindentation tests, which is of important potential interest for industrial and medical applications.

Bio-based polymer nanocomposites based on nylon 11 and WS2 inorganic nanotubes

Tungsten disulphide nanotubes (INT-WS2) have been successfully dispersed in a bio-based polyamide matrix (nylon 11) by conventional melt processing. The effect of INT-WS2 content on the morphology, thermal stability, crystallization behaviour and dynamic mechanical properties is investigated. The results indicate that these inorganic nanotubes can be efficiently incorporated into the bio-based polymer matrix without the need for modifiers or surfactants. Additionally, it is found that the non-isothermal crystallization behaviour of nylon 11/INT-WS2 depends on both the cooling rate and INT-WS2 concentration. In particular, crystallization kinetics results demonstrate that the nucleating activity of INTs plays a dominant role in accelerating the crystallization of nylon 11. This fact leads to the appearance of the more-disordered phase at higher temperature. More significantly, it was shown that these INT-WS2 nanocomposites can facilitate a good processability and cost efficiency, and will be of interest for many eco-friendly and medical applications.