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Nanocomposites based on thermoplastic polyurethane (TPU) and poly lactic acid (PLA) with different weight ratios of 10:90 and 30:70 were prepared by solution method. Hydroxyapatite nanoparticles (n-HA) were used to enhance the physical and mechanical properties of the alloys. To prepare the nanocomposites, the percentages of n-HA varied between 1% and 5%. Different tests were used to investigate the properties of these nanocomposites. Scanning electron microscopy (SEM) analysis, which was used to study the morphology of the blends, showed that there were rough morphologies in between materials, and the results of the mapping test showed that the dispersion of nanoparticles in the polymer matrix was almost good. TGA thermal degradation test showed that the presence of TPU to some extent can affect the thermal stability properties, and with the increase in this material, the thermal properties are strengthened. The crystalline behavior of the samples showed that the presence of TPU and n-HA nanoparticles had negative effects on the crystalline properties. The study of viscoelastic behaviors showed that the presence of TPU enhances the viscous behavior in the sample and decreases the glass transition temperature, while the presence of nanoparticles increases the elastic properties and glass transition temperature. Tensile test showed that the presence of n-HA has a greater effect on the mechanical properties. Dynamic contact angle analysis using water and dimethylformamide (DMF) solvent showed that the existing TPU and n-HA led to major changes in the interaction surface of scaffolds. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis showed that increasing the amounts of TPU and HA increases cell viability. SEM cell interactions analysis showed that the surfaces of PLA90TPU10H5 and PLA70TPU30H5 samples are very good for the preparation of bone tissue scaffolds. Our findings indicated that the addition of n-HA into PLA/TPU blends could impart new features to the PLA matrix as a promising candidate for bone, cartilage, and tendon tissue engineering.

The presence of residual organic dyes in water resources results in a threat for both environment and human health due to their adverse health effects such as mutagenicity, carcinogenicity, and teratogenicity. Thus, they must be removed from industrial wastewater. Among these dyes, methylene blue (MB) is a toxic, carcinogenic, and almost non-biodegradable dye and can pose a significant threat to human health and environmental safety. Thus, it is removed from industrial effluents by a variety of methods, including adsorption, prior to discharge into the environment. This study aims to optimize the adsorption conditions of MB from an aqueous solution with nanocomposite of silver onto single-wall carbon nanotube metronidazole (Met-SWCNTs/Ag). Response Surface Methodology (RSM) based on Central Composite Design (CCD) is used to optimize and model the adsorption of MB dye (as pollutant) on Met-SWCNTs/Ag. The Met-SWCNTs/Ag is synthesized using Met-SWCNT impregnated with silver nitrate. The produced Met-SWCNT/Ag nanocomposite is characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The effect of four independent variables including nanoparticle (NP)/dye ratio, temperature, pH and contact time on MB removal on the specific surface area of SWCNT/Ag and Met-SWCNTs/Ag is evaluated. The accuracy and fit of the model for MB removal using Met-SWCNTs/Ag are estimated by ANOVA with R2 > 0.99 and P-value < 0.0001. RSM results indicates that the NP/Dye ratio has the most significant influence on the adsorption of MB onto Met-SWCNTs/Ag. The optimal condition of the adsorption process takes place at NP/Dye ratio of 2.21, contact time of 65.57 min, and pH = 6.15 at 25.79 °C temperature leading into a 98.94 % MB removal. Isotherms and kinetic studies are performed to characterize the adsorption behavior of the adsorbent for MB removal. The adsorption behavior of the MB onto Met-SWCNTs/Ag is best described by the Langmuir isotherm model with regression coefficient R2 of 0.9935 with the Qmax of 112.42 mg/g. Adsorption kinetics of Met-SWCNT/Ag is investigated and modelled by means of the pseudo-first-order, pseudo-second-order models which is best fitted to the pseudo-second-order model. The thermodynamic study reveals that the adsorption of MB dye is spontaneous and exothermic. Experimental results suggest that the modified SWCNTs/Ag with Met achieves a higher removal efficiency of (∼98 %) when compared to SWCNTs/Ag (∼93 %). [ABSTRACT FROM AUTHOR]

A series of 3-D scaffolds based on polylactic acid (PLA) and thermoplastic polyurethane (TPU) as major phase and hydroxyapatite nanoparticles (n-HA) were prepared by using the dual leaching technique. Fourier-transform infrared spectroscopy analysis showed that almost the interactions between the constituent materials can be identified based on their functional groups. The results of thermogravimetric analysis were used to obtain the best time to prepare the samples without residual of any progen additives. The scanning electron macroscopy images clearly proved that the dual leaching technique is an effective method to prepare the appropriate morphology and also a very good dispersion and distribution for n-HA can be obtained. Dynamic contact angles showed that the presence of TPU in the PLA matrix has a positive effect on the hydrophilicity of the scaffolds. The bulk modulus (κ) values of S-PLA70TPU30H5 in dry and wet conditions were 321 and 212 Pa, respectively and the compressibility coefficient (β) of pure samples was higher than that of other scaffolds, while among the nanocomposite samples, the compressibility coefficient of S-PLA70TPU30H5 and S-PLA50TPU50H5 samples in dry and wet conditions was higher than that of other samples. Biological tests such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, cell adhesion, 4′,6-diamidino-2-phenylindole (DAPI) analysis and alizarin red were also performed, and the results obtained for 3D scaffolds were good. In the DAPI analysis test, sample 3D-S-PLA70TPU30H5 showed good behavior, and also in the alizarin red test, the amount of minerals created in 3D-S-PLA50TPU50H5 was significant. Dual leaching technique was used to prepare cylindrical scaffolds with high porosity. 3D cylindrical scaffolds based on PLA/TPU/n-HA were proposed for use in cancellous bone. Bulk modulus and compressibility coefficient of 3D cylindrical scaffolds were obtained in wet and dry conditions. DAPI analysis showed the role of n-HA nanoparticles on cell growth in 3D cylindrical scaffolds. Alizarin red studies showed that sample PLA50TPU50H5 has more calcium content. [ABSTRACT FROM AUTHOR]

In this study, thermal stability behavior and flammability of ethylene-vinyl-acetate (EVA) copolymers containing organo-modified nanoclay particles (Cloisite 15A) and ammonium polyphosphate (APP) along with pentaerythritol (PER), as halogen-free flame retardants, were investigated. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) were employed for evaluation of the level of dispersion of nanosheets within the EVA matrix. Moreover, thermal stability behavior and flammability of the samples were studied using thermogravimetric analysis (TGA), cone calorimetry thermometer (CCT) and limiting oxygen index (LOI). The obtained results from TEM and SAXS showed that nanosheets exhibited a rather proper level of dispersion within the EVA matrix. According to TGA and CCT results, despite improving the thermal stability and flame retardancy of EVA due to incorporation of the individual additives, a considerable synergistic effect was observed upon simultaneous use of clay nanosheets and the flame retardants. Such synergistic effect was explained by the physical mechanism of the solid phase due to the increased residual ash resulted from combustion of the samples containing flame retardants and clay nanosheets. While clay nanosheets had no significant effect on the LOI of EVA, the halogen-free flame retardants substantially increased the LOI of EVA. J. VINYL ADDIT. TECHNOL., 23:E92-E98, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Compatibilized and non-compatibilized polypropylene/ethylene vinyl acetate copolymer (PP/EVA) blends loaded with 5 wt% of fullerene-like tungsten disulfide nanoparticles (IF-WS 2 ) as an inorganic nano-filler were prepared by melt mixing process and their thermal and dynamic mechanical properties were determined. TEM investigations revealed that the IF-WS 2 nanoparticles were mainly located within the EVA phase of the blend. Also, microstructure of blends studied by SEM showed that incorporation of IF-WS 2 into the blends led to reduction of dispersed domain size attributed to reduction of interfacial tension due to the filler presence. Melting temperature of PP loaded with 5 wt% of IF-WS 2 was increased up to 13 °C as compared to the neat PP. Addition of IF-WS 2 and PP-g-MAH as compatibilizer to PP/EVA blend increased melting and crystallization temperatures determined by DSC. DMTA studies showed that addition of IF-WS 2 into the blends had no positive effect on the storage modulus of nanocomposites while, their loss modulus were higher than that of the neat PP. Moreover, the β transition temperature of PP phase in the blends loaded with IF-WS 2 and compatibilizer was about 6 °C higher than the neat PP. The thermo-oxidative and thermal degradation behavior of developed nanocomposites determined by thermal gravimetric analysis (TGA) showed that thermal stability of nanocomposites was improved and their rate of degradation was reduced which were attributed to network-like structure formation of nano-fillers in the blends. [ABSTRACT FROM AUTHOR]

A series of 3-D scaffolds based on polylactic acid (PLA) and thermoplastic polyurethane (TPU) as major phase and hydroxyapatite nanoparticles (n-HA) were prepared by using the dual leaching technique. Fourier-transform infrared spectroscopy analysis showed that almost the interactions between the constituent materials can be identified based on their functional groups. The results of thermogravimetric analysis were used to obtain the best time to prepare the samples without residual of any progen additives. The scanning electron macroscopy images clearly proved that the dual leaching technique is an effective method to prepare the appropriate morphology and also a very good dispersion and distribution for n-HA can be obtained. Dynamic contact angles showed that the presence of TPU in the PLA matrix has a positive effect on the hydrophilicity of the scaffolds. The bulk modulus ( κ ) values of S-PLA70TPU30H5 in dry and wet conditions were 321 and 212 Pa, respectively and the compressibility coefficient ( β ) of pure samples was higher than that of other scaffolds, while among the nanocomposite samples, the compressibility coefficient of S-PLA70TPU30H5 and S-PLA50TPU50H5 samples in dry and wet conditions was higher than that of other samples. Biological tests such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, cell adhesion, 4',6-diamidino-2-phenylindole (DAPI) analysis and alizarin red were also performed, and the results obtained for 3D scaffolds were good. In the DAPI analysis test, sample 3D-S-PLA70TPU30H5 showed good behavior, and also in the alizarin red test, the amount of minerals created in 3D-S-PLA50TPU50H5 was significant.

Background and Objectives: Lipases are valuable biocatalysts which are widely used in the detergent, food, dairy and pharmaceutical industries. The aims of the present study included the isolation of a lipase-producer from industrial zones and the partial characterization of the enzyme., Materials and Methods: A number of bacteria were isolated from sites related to the oil industries. An isolate forming a halo zone in a selective medium (TW agar) was then selected and grown on a medium suitable for the production of lipase. The isolate was subsequently identified by the 16S rRNA sequencing method, and its enzyme activity was measured by a spectrophotometer using pNPP as a substrate., Results: The selected isolate was identified by the molecular method as Pseudomonas sp. Its extracellular lipase activity was 41.5 ± 1.4 U/ml, and the high affinity of this enzyme for the substrate was indicated by the kinetic parameters of Km and Vm, which were estimated by the the Lineweaver-Burk plot as 0.77 mM and 49.5 U/ml, respectively. Activation energy of lipase calculated from the Arrhenius plot was found to be 20.78 kJ/mol, and a temperature coefficient (Q10) of 4.39 indicated the high catalytic activity of the enzyme and the temperature dependence of the enzymatic reaction., Conclusion: The results demonstrated that the indigenous isolate could have potential applications in many relevant industries.