Polyurethane/clay nanocomposites with improved helium gas barrier and mechanical properties: Direct versus master‐batch melt mixing route

Thermoplastic polyurethane (TPU)/clay nanocomposite films were produced by incorporation of organo‐modified montmorillonite clay (Cloisite 30B) in TPU matrix by two different melt‐mixing routes (direct and master‐batch‐based mixing), followed by compression molding. In master‐batch mixing where the master‐batch was prepared by mixing of clay and TPU in a solvent, better dispersion of clay‐layers was observed in comparison to the nanocomposites produced by direct mixing. As a consequence, superior mechanical and gas barrier properties were obtained by master‐batch mixing route. The master‐batch processing resulted in 284 and 236% increase in tearing strength and tearing energy, respectively, with 5 wt % clay‐loading. Interestingly, in case of master‐batch mixing, the tensile strength, stiffness as well as breaking extension increased simultaneously up to 3 wt % clay‐loading. The helium gas permeability reduced by about 39 and 31% for the TPU/clay nanocomposites produced by mater‐batch and direct mixing routes, respectively, at 3 wt % loading of clay. Finally, the gas permeability results have been compared using three different gas permeability models and a good correlation was observed at lower volume fraction of clay. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46422.     

Exploration of photoreduction ability of reduced graphene oxide–cadmium sulphide hetero-nanostructures and their intensified activities against harmful microbes

Journal of Materials Science - Fabrication of effective photocatalyst using semiconductors and graphene or reduced graphene oxide has been regarded as one of the most promising task to attenuate...     

Studies on the dyeability and dyeing mechanism of polyurethane/clay nanocomposite filaments with acid,basic and reactive dyes

Polyurethane/clay nanocomposite (PUCN) filaments were spun by the dry‐jet‐wet spinning method. To prepare the PUCN filaments, 0.25, 0.50 and 1% of nanoclay on the weight of polyurethane were incorporated in the polyurethane dope. The interaction between clay and polyurethane was analysed by attenuated total reflectance–Fourier Transform‐infrared (ATR‐FTIR) spectroscopy. The structure and morphology of the PUCN filaments were analysed by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). Both the neat polyurethane and the PUCN filaments were dyed with different acid, basic and reactive dyes. The neat polyurethane filaments exhibited poor dyeability with all three classes of dyes. By contrast, the PUCN filaments showed a significantly higher dye uptake with all of the dyes used. Furthermore, the dye uptake increased significantly as the percentage of clay in the filaments increased, as indicated by the increase in the K/S values of the dyed filaments. The dyeing mechanism with all three dyes, as well as the increased dyeability of the PUNC filaments in comparison to those of the neat polyurethane filaments, was discussed.     

Effect of pressure on structure and properties of lyocell fabric-based all-cellulose composite laminates

In this work, all-cellulose composite (ACC) laminates were manufactured from lyocell fabric using a simple hand lay-up and compression molding-based surface-selective dissolution technique. In dissolution step, temperature and dissolution time were fixed and pressure varied. Subsequently, the dissolved cellulose was regenerated via solvent exchange and then dried by hot-pressing. The microstructures of ACC laminates were analyzed by scanning electron microscope micrographs and measuring void content. Optimum microstructure and mechanical properties were obtained with a pressure of 1 MPa, but slightly deteriorated with further increase in pressure. The highest tensile strength and modulus achieved were 44.24 ± 2.2 MPa and 1.78 ± 0.14 GPa, respectively, for ACC-3. Best flexural strength and modulus obtained were 48.95 ± 2.87 MPa and 0.96 ± 0.21 GPa, respectively, for the same sample. The T-peel strength of ACC-3 also was very high, 2.78 ± 0.34 MPa. Application of pressure during drying had a great role on controlling shrinkage and internal voids in ACC laminates.     

Correction to: Exploration of photoreduction ability of reduced graphene oxide–cadmium sulphide heteronanostructures and their intensified activities against harmful microbes

Journal of Materials Science -     

Effect of the dissolution time on the structure and properties of lyocell‐fabric‐based all‐cellulose composite laminates

In this study, all‐cellulose composite laminates were prepared from lyocell fabric with ionic liquid (1‐butyl‐3‐methyl imidazolium chloride), a conventional hand layup method, and compression molding. Eight layers of lyocell fabric, which were impregnated with ionic liquid, were stacked symmetrically and hot‐pressed under compression molding for various times; this resulted in the partial dissolution of the surface of the lyocell fibers. The dissolved cellulose held the laminas together and resulted in a consolidated laminate. Finally, the prepared laminate was impregnated in water to remove the ionic liquid and to regenerate a matrix phase in situ; this was followed by hot‐press drying. Optical microscopy and scanning electron microscopy studies were used to analyze composite structures. With increasing dissolution time, the void content in the composites decreased, and the interlaminar adhesion improved. For LC‐2h and LC‐3h, the highest tensile strength and modulus values obtained were 48.2 MPa and 1.78 GPa, respectively. For LC‐4h, the highest flexural strength and modulus values obtained were 53.96 MPa and 1.2 GPa, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43398.