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Polypropylene (PP) was compounded with β-nucleating agent and injection-molded at 180 °C or 220 °C. The samples were subsequently treated by supercritical carbon dioxide (scCO 2 ) at different temperatures. Results show that processing temperature and scCO 2 treatment could strongly influence the tensile and impact properties of β-nucleated PP. In particular, the sample processed at 220 °C and treated at 120 °C exhibit much enhanced impact strength (4.8 times that of its untreated counterpart). FTIR, WAXD, SEM and DMA were performed to explore the effects of processing temperature and scCO 2 treatment on structure of the samples. Deformation-induced plastic flow and micro-voids were also evaluated to construct structure-property relations. It was found that the influence of processing temperature on mechanical properties is mainly associated with the β-form content and β-crystalline morphology, while the structural changes in the crystalline lamellar scale may be responsible for the toughening effect of scCO 2 treatment. [ABSTRACT FROM AUTHOR]

Heterojunctioned architectures were facilely fabricated using hydrothermally treated electrospun TiO 2 nanofibers in an alkaline Sr(NO 3 ) 2 precursor solution in an electronic oven. TiO 2 on the fiber surface was partially dissolved into Ti 4+ to react with Sr 2+ in favor of the nucleation of SrTiO 3 on TiO 2 nanofibers, and thus a heterojunction was formed between SrTiO 3 and TiO 2 , which will benefit the improvement of photocatalytic activity. And then a multifunctional membrane was created by functionalizing the surface of commercial cellulose acetate (CA) membrane with heterojunctioned SrTiO 3 /TiO 2 nanofibers. This newly structured membrane exhibited excellent water purification performances in a concurrent photocatalytic membrane filtration system under the irradiation of UV light, because it is able to integrate the advantages of photocatalysis and membrane filtration while minimizes their disadvantages. The high water purification performances in terms of high photodegradation ability and high permeate flux are attributed to the high photocatalytic activity of heterojunctioned SrTiO 3 /TiO 2 nanofibers architectures and their structured porous functional layer favorable for fast water pass through. [ABSTRACT FROM AUTHOR]

In this work, influence of matrix crystallization on the electrical conductivity and mechanical properties of poly( l -lactide)/multiwalled carbon nanotubes (PLLA/MWCNTs) nanocomposites has been investigated. By introducing trace amount of nucleating agent (0.15 wt%) and controlling isothermal crystallization time (0.1–8 min) of PLLA matrix in a hot mould (130 °C), the injection molded bars of the nanocomposites with different matrix crystallinities (5–45%) were prepared. Interestingly, the electrical conductivity is found to be linearly increased with increasing matrix crystallinity for nanocomposites with low concentrations of MWCNTs (below the percolation threshold). This could be attributed to the volume exclusion effect and the straightening effect of MWCNTs provided by PLLA crystallization, as evidenced from SEM observations. However, matrix crystallization induced reconstruction of MWCNTs network cannot effectively enhance the electrical conductivity when the concentration of MWCNTs is high enough (above the percolation threshold). More interestingly, the reconstructed MWCNTs network shows a better reinforcement effect in the nanocomposites as compared with that initially formed in the amorphous matrix. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel-structured TiO2/CuO composite nanofibers was optimized for H2 generation. [ • ] Vivid changes of physicochemical properties influenced by calcinations temperature. [ • ] Significance of physicochemical properties synergy on H2 generation was revealed. [ • ] The optimized photocatalyst exhibited the highest H2 generation activity. [ • ] Reusable and stable with negligible Cu leaching. [Copyright &y& Elsevier]

Abstract: Here, hierarchically meso/nanoporous TiO2 was successfully fabricated by a facile and efficient hydrolysis and calcination method using Ti(OC4H9)4 and K2S2O8 as precursors. The hydrosol was firstly prepared by drop-wise adding ethanol dissolved Ti(OC4H9)4 solution into acetone dissolved K2S2O8 solution under a vigorous stirring and heating condition. After being sufficiently hydrolyzed, the hydrosol was calcined to promote the crystallization of TiO2 and successfully dope S and C on TiO2. The calcination temperature significantly affects the doping of S and C on TiO2, crystallization of TiO2, formation of hierarchically meso/nanoporous structure of TiO2 and its light absorption capability. The S- and C-codoped TiO2 exhibits high photocatalytic H2 generation efficiency in a water/methanol sacrificial reagent system under the irradiation of UV light. The high photocatalytic efficiency is dependent on the comprehensively competing effects of the codoping of S and C, crystallization, specific surface area and light absorption capability. The S- and C-codoped TiO2 calcined at 600°C demonstrates the highest photocatalytic H2 generation efficiency, which is ascribed to the balanced synergy of the abovementioned factors. [Copyright &y& Elsevier]

Abstract: The effect of fabrication method on the properties of hierarchical 3D TiO2 nanostructures was investigated by employing and developing both hydrothermal method and calcination method to synthesize hierarchical 3D TiO2 nanorod spheres in this study. A comprehensive comparison in terms of morphologies, crystallization, specific surface areas, light absorption capabilities, and photoluminescence spectrum was conducted between 3D TiO2 nanorod spheres synthesized via hydrothermal method and that synthesized via calcination method. A better photocatalytic activity was demonstrated over the TiO2 nanorod spheres synthesized through calcination method. This was ascribed to the better crystallization and monodispersion of the hierarchical 3D TiO2 nanorod spheres resulted from the calcination method; thus rendering it with more superior characteristics such as larger specific surface area, enhanced light absorption capability and faster transfer of electrons which suppress the recombination of photogenerated electrons and holes. This study is thus significant not only in promoting the development of hierarchical 3D TiO2 nanorod spheres via different methods, but also in revealing the effect of fabrication method on the photocatalytic activity of hierarchical 3D TiO2 nanorod spheres. The calcination method is proposed to be a facile and promising method for scale-up production of the hierarchical 3D TiO2 nanorod spheres with high photocatalytic activity for efficient pollutants degradation. [Copyright &y& Elsevier]

Abstract: To counter the global water crisis such as water resources scarcity and water quality deterioration, membrane filtration has been widely used as a promising technology. Recently, nano-materials and its structured membranes demonstrated multifunctional water purification capability in terms of decontamination and disinfection. Here, hierarchical nitrogen (N)-doped “nut-like” ZnO nanostructured material was hydrothermally synthesized at large scale. This hierarchical N-doped “nut-like” ZnO nanostructured material was well characterized and successfully assembled on a piece of polymer membrane surface to create a multifunctional membrane. This newly developed membrane demonstrated high pollutants removal ability via rejection and photodegradation, and strong antibacterial growth ability under visible light irradiation. At the same time, this novel membrane holds the potential to produce clean water at a constant high flux. The experimental results indicated that the hierarchical N-doped ZnO “nut-like” nanostructured material enhanced the photocatalytic activity in a comparison to commercial ZnO powder. This is caused by enlarging the specific surface area and enhancing the light utilization rate. It is reasonable to believe this hierarchical N-doped “nut-like” ZnO nanostructured membrane would benefit the water purification field. [Copyright &y& Elsevier]

Abstract: Through hydrothermally growing SrTiO3 cubics on the surface of electrospun TiO2 nanofibers, SrTiO3/TiO2 nanofibers heterostructures were successfully fabricated in the present study. This process is able to ensure uniform distribution of SrTiO3 on the surface of TiO2 nanofibers and lead to close contact between SrTiO3 and TiO2, which is beneficial for the fast separation of photogenerated electrons and holes so as to suppress the recombination of photogenerated electrons and holes at the interphase of SrTiO3 and TiO2. Besides this, the long 1D fibrous structure easy for electron transfer, the hierarchical structure promoting mass transfer and allowing more light reflection and absorption, and the large specific surface area providing more reactions sites to facilitate the reactants to desired oxidation places all together create a synergistic effect on improving the photocatalytic activity of the hierarchical SrTiO3/TiO2 nanofibers heterostructures. Under the irradiation of UV light, in a water/methanol sacrificial reagent system, the SrTiO3/TiO2 nanofibers heterostructures generate five times more H2 than bare TiO2 nanofibers because of its high photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Hierarchical porous TiO2 hollow microspheres were synthesized by a facile approach from a one-step template method. This novel approach avoids tedious multiple steps from conventional template method for fabricating hierarchical porous and hollow microspheres. The as-prepared microspheres were characterized by XRD, SEM, TEM, nitrogen adsorption, and UV–vis DRS. Its photocatalytic activity was demonstrated in the photocatalytic degradation of Rhodamine B. Structural characterization indicates that the as-prepared microspheres had a hollow interior and a hierarchical porous structure with both large and small mesopores on its surface. The average diameters and BET surface areas of the hierarchical porous TiO2 hollow microspheres were 1.5μm and 117m2/g, respectively. Optical adsorption investigation shows that the hierarchical porous TiO2 hollow microspheres possessed the optical band gap of 3.42eV. A possible formation mechanism for the hierarchical porous TiO2 hollow microspheres was discussed. The hierarchical porous TiO2 hollow microspheres exhibited much higher photocatalytic activity than the commercial P25 TiO2. In addition, the as-prepared microspheres can be easily recycling for reuse. All these advantages show a bright future for this microspheric photocatalyst in environmental purification. [Copyright &y& Elsevier]

In this study, bismuth/titanium oxide (Bi3+/TiO 2) composite nanofibers (herein after referred to as Bi/TiO 2) with enhanced physicochemical properties thus photocatalytic efficiency are successfully synthesized via electrospinning which maximizes the uniformity of Bi and Ti at molecular level. Bi/TiO 2 shows positive characterization through anatase crystallinity, large light utilization rate, high specific surface area and low electron holes pair recombination rate as a result of the novel materials synthesis approach. Glycerol as a typical pollutant of industrial wastewater, is used here to demonstrate the concurrent production of chean water and H 2 over the well synthesized Bi/TiO 2. Bi is incorporated to extend the light absorbance capability of TiO 2 to visible light region. Experimental data shows that 3% Bi/TiO 2 exhibits the highest H 2 generation and Total Organic Carbon (TOC) removal. The reduction of TOC of 8% means the conversion of glycerol into H 2 has been achieved, which is in favor of the production of clean water from highly polluted glycerol wastewater. An optimization study is undertaken by varying the calcination temperature to investigate properties-activity relationship of the new photocatalyst, which exhibited higher photocatlytic efficiency under both UV–visible and visible light compared with that of bare TiO 2. The mechanism illustration is derived from the novel materials synthesis and property optimization to explain the rationale behind this interesting phenomenon. It is worth to note that Bi/TiO 2 nanofibers represent a promising photocatalyst for environmental remediation and sustainability where it can be potentially used in glycerol by-product or waste from the industry under the renewable solar irradiation to generate H 2 and clean water simultaneously. [Display omitted] • Bi-incorporated TiO 2 nanofibers exhibited to be able to concurrently generate H 2 and clean water under solar irradiation. • Enhanced physico-chemical properties of Bi/TiO 2 nanofibers. • Enlarged specific surface area & unique mesoporosity. • Enhanced light absorption capability for better photocatalytic reaction, and. • Well-dispersed heterojunctions for an efficient electrons-holes separation. [ABSTRACT FROM AUTHOR]

• A novel airfoil flow field is proposed for fuel cells. • Airfoil flow field can enhance mass transfer while maintain low pressure drop. • Fuel cell with airfoil flow field is evaluated via experimental test and simulation. • Airfoil flow field increases the fuel cell's maximum power density effectively. • Airfoil flow field promotes the uniform distributions in fuel cells. Optimal configuration of bipolar plate (BP) embedding flow field is of great significance in improving the power density and durability of proton exchange membrane fuel cells (PEMFCs). Inspired by the airfoil in aircraft dividing the airflow into two streams causing pressure difference, a novel airfoil flow field (AFF) is designed to enhance the mass transfer capacity in channel and across the rib between two adjacent channels, which hardly increases the pressure drop in channel, unlike many baffle designs. The performance improvement achieved by implementing AFF in PEMFC is compared with common parallel flow field (PFF) and the wave flow field (WFF) by experimental test with respect to polarization curve and electrochemical loss and numerical simulation via a three-dimensional (3D) PEMFC model. The experimental results indicate that the novel AFF exhibits best fuel cell performance at various operation conditions (e.g. relative humidity, air stoichiometric ratio) mainly benefitted from the enhanced oxygen transfer, which contributes to the improvement of maximum power density by 8.85 % and 14.37 % compared to PFF and WFF, respectively. The modeling results indicate that the pressure drop increase in AFF is negligible compared with PFF, and is even slightly lower than WFF, indicating high practicability. Moreover, the utilization of AFF also helps the uniformity of oxygen concentration, current density and temperature in PEMFC. [ABSTRACT FROM AUTHOR]

Abstract: Here we present a simple two-phase assembling method to produce high-quality graphene oxide–TiO2 nanorod composites (GO–TiO2 NRCs) on gram scale. TiO2 nanorods dispersed in toluene are synthesized from a facile two-phase hydrothermal method. The effective attachment of TiO2 nanorods on the whole GO sheets at the water–toluene interface is confirmed by Transmission Electron Microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The as-synthesized TiO2 nanorods show a slightly higher efficiency in the photocatalytic degradation of C. I. Acid Orange 7 (AO 7) irradiated under UV light (λ =254nm) and higher antibacterial activity under simulated sunlight than that of TiO2 nanoparticles with the same diameter. After combined with graphene oxide (GO), the GO–TiO2 NRCs show much higher photocatalytic activities than that of TiO2 nanorods alone and the GO–TiO2 nanoparticle composites (GO–TiO2 NPCs). The ratio of TiO2 and GO has no evident effect on the photocatalytic activity of GO–TiO2 NRCs when all the TiO2 nanorods are anchored on the GO sheets. The higher photocatalytic activity of GO–TiO2 NRCs is ascribed to the anti-charge recombination and the more (101) facets. Considering the superior photocatalytic activity of GO–TiO2 NRCs and the fact that they can been easily mass-produced, we expect this material may find important applications in environmental engineering and other fields. [Copyright &y& Elsevier]

Ultrathin and/or ultrasmooth selective layer is one of the paramount goals in membrane realm for maximizing separation efficiency and/or minimizing fouling tendency. Towards this goal, the architecture of hydrogel selective layer is finely tuned for the first time for improving engineered osmosis (EO) membrane performance. Through delicately controlling synthesis parameters, ultrathin selective layer as thin as 30 nm, and ultrasmooth selective layer with sub-1 nm roughness (the smoothest EO membrane in literature) are successfully synthesized respectively. Analysis of reverse osmosis (RO) experimental results reveals hydrogel layer resistance to water permeation is linearly reduced by 1.40 × 1013 m−1 as the layer is tailored thinner per 10 nm, which leads to the remarkable enhancement of water permeability by ~10 times from 0.49 L m−2 h−1 bar−1 of 500 nm thickness to 4.75 L m−2 h−1 bar−1 of 30 nm thickness. Pressure-retarded osmosis (PRO) and forward osmosis (FO) tests indicate 45-nm-thick hydrogel layer achieves the maximum separation efficiency in terms of specific water flux (J W /J S). Moreover, the mechanism for tuning hydrogel layer architecture is discussed on the basis of microscopic characterizations. This study sheds new light on ultrathin and ultrasmooth selective layer for promoting EO membrane to smartly tackle different kinds of wastewater. Ultrathin and ultrasmooth hydrogel membranes are synthesized through fine-tuning selective layer architecture for smartly tackling different wastewaters via engineered osmosis with high separation performance. Image 1 • Hydrogel membrane architecture is fine-tuned for engineered osmosis. • Ultrathin hydrogel selective layer as thin as 30 nm is synthesized. • Ultrasmooth hydrogel selective layer with sub-1 nm roughness is achieved. • The effect of hydrogel layer architecture on separation performance is revealed. • Hydrogel membrane holds the promise to smartly tackle different wastewaters. [ABSTRACT FROM AUTHOR]

The preparation of elastomer/plastic blends with co-continuous structure is beneficial to achieve good shape recovery and fixing performances. In this work, carbon black (CB) nanoparticles with self-networking capability were introduced to tailor the phase morphology and shape memory properties of polylactide (PLA)/thermoplastic poly(ether) urethane (TPU) blend (70/30 by weight). A morphological change from sea-island structure to co-continuous structure was observed with increasing CB content. The strong affinities between CB nanoparticles and TPU as well as the self-networking capability of CB nanoparticles led to the formation of this co-continuous structure. With such novel structure, the PLA70/TPU30/CB ternary composites owned an outstanding shape memory property because the continuous TPU phase provided stronger recovery driving force. Moreover, the selective localization of CB nanoparticles in the continuous TPU phase imparted the composites with enhanced mechanical properties and excellent electrical conductivities with low filler content. The composites then showed a good electroactive shape memory behavior, which could recover to their original shape within 80 s at 30 V. Our work provides a universal strategy via CB self-networking to prepare double percolated conductive polymer composites with optimal shape memory properties and excellent electrical conductivities, which may promote specific applications in intelligent devices. [ABSTRACT FROM AUTHOR]

There are principally two mechanisms to improve the impact resistance of polymer-based composites, intrinsic toughening and extrinsic toughening. But the interplay between them is far from being well understood. Here, glass fiber was incorporated into polypropylene to promote extrinsic toughening mechanism, while addition of elastomer and annealing were adopted for intrinsic toughening. In this way, the interaction among glass fiber, elastomer and annealing could be discussed based on various characterizations, and their combined effect on mechanical properties of the composites could be determined. The results show that the intrinsic toughening mechanism of elastomer will be suppressed by glass fiber irrespective of the support of annealing, though annealing could work synergistically with glass fiber to toughen polypropylene. The possible structure-property relations are discussed. This work will provide deeper insight into the toughening behavior of polymer composites and practical guidance for the design of composites with excellent stiffness-toughness balance. [ABSTRACT FROM AUTHOR]

Bio-degradable polylactide (PLA) based composites has attracted much attention both in academic research and industrial applications in recent decades due to the increasing environmental concerns. In this work, we tried to obtain PLA based composites with good stiffness-toughness balanced properties by adjusting carbon fiber (CF) network in polylactide (PLA) matrix via adding a small amount of soft poly(ether)urethane (PU). It was interesting to find that PU could serve as “solder” to weld CF into a more perfect network due to the fact that PU has stronger interaction with CF as compared with PLA and improve the interface interaction between CF and PLA meanwhile. The self-weld CF network structure was confirmed by SEM characterizations, rheology and conductivity tests. More importantly, the formation of self-weld network structure constructed by both stiff CF and ductile PU elastomer can simultaneously improve tensile strength, impact toughness and even electrical conductivity of PLA. This inspiring result demonstrates that the addition of soft elastomer which has a strong interaction with fiber into fiber-reinforced polymers could be a universal platform to improve the performance of polymer composites via tuning fibers network and the interfacial interaction between fibers and polymer matrix. [ABSTRACT FROM AUTHOR]

As a novel thermoplastic elastomer, olefin block copolymers (OBCs) show a tremendous application potential in many areas. However, the practical use of OBCs is mainly restricted to the low load-bearing environments because of its poor low-strain mechanical strength and stiffness. In this work, short Kevlar fiber was introduced into OBC matrix to improve its mechanical properties. The results show that introduction of pristine Kevlar fiber only gives rise to a slight increase in tensile strength of OBC owing to the poor interfacial strength, regardless of the presence of compatibilizer maleic anhydride-grafted polypropylene (MA-g-PP). However, a largely enhanced tensile strength can be easily obtained when hydrolyzed or polydopamine-coated Kevlar fiber was incorporated into the OBC matrix using the MA-g-PP as the reactive compatibilizer. More importantly, the tensile strength can be further enhanced with the orientation of Kevlar fiber in the composites. As compared with compression molded composites with randomly orientated fibers, injection molded composites with highly oriented fibers exhibit a significantly higher tensile strength at the same composition. Moreover, it is interesting to observe that Kevlar fiber can be easily exfoliated into several microfibers during melt-mixing with OBC, but the exfoliation has no evident effect on the reinforcement effect possibly because of the poor interfacial strength between the newly-formed microfibers and the OBC matrix. Our work demonstrates that mechanical performance of short fiber reinforced elastomer composites could be significantly improved by enhancing interfacial strength and fiber orientation using a facile surface modification strategy and conventional melt-processing technology. [ABSTRACT FROM AUTHOR]

Abstract: β-Modification and annealing were adopted to improve the impact strength of long glass fiber reinforced (LFPP) composites. It was found that either β-modification or annealing is an efficient way to toughen LFPP composites, and largely enhanced impact toughness can be achieved via simultaneously using β-modification and annealing, particularly for the toughness at low temperatures (−40°C to −20°C). Meanwhile, the tensile strength and Young’s modulus of the composites could be maintained. Various characterizations were used to understand the microstructure changes and toughening mechanism after β-modification and annealing. The results show that the higher extent of the matrix plastic deformation could be the main reason for the enhanced toughness as induced by β-modification and annealing. The possible structural origins for the higher extent of matrix plastic deformation are also discussed. [Copyright &y& Elsevier]

Abstract: Sodium hydrosulfite is used to reduce graphite oxide in current study. The preparation of poly (vinyl alcohol) (PVA)/graphene nanocomposites is realized using two simple steps: the synthesis of PVA/graphite oxide (GO) nanocomposites film and immersion of such a film in the reducing agent aqueous solution. This method prohibits the agglomeration of GO during direct reduction in PVA/GO aqueous solution, and opens a new way to scale up the production of graphene nanocomposites using a simple reducing agent. A 40% increase in tensile strength and 70% improvement in elongation at break have been obtained with only the addition of 0.7wt.% of reduced graphite oxide. Furthermore, a good level of conductivity and a variation in the surface property of the prepared films have been observed for the composites containing graphene. [Copyright &y& Elsevier]

Abstract: One-dimensional mesoporous TiO2 nanotube (TNT) with large specific surface area was successfully fabricated, and employed in removal of Acid Orange 7 (AO7) via adsorption and heterogeneous photocatalysis. As compared to its precursor, P25 (Degussa), TNT exhibited superior adsorption ability and photocatalytic activity. It was found that the amount of adsorbed dye over TNT surface was critical to the photodegradation efficiency of AO7, and adsorption was further controlled by solution pH and co-existing ions. With an increase in pH, adsorption of AO7 decreased rapidly, and adsorption behavior transformed from monolayer adsorption to asymmetric physisorption. Under low pH conditions, multivalent anions in high concentrations severely limited AO7 adsorption on TNT; whereas the increase of pH led to a less severe inhibition of the adsorption. On the other hand, multivalent cations seem to facilitate adsorption, regardless of pH conditions. Adsorption mechanism and photodegradation kinetics of AO7 on TNT were also discussed in the paper in view of paving the way for efficient dye wastewater treatment with the application of TNT photocatalyst. [Copyright &y& Elsevier]

Abstract: The impact fracture behaviors of polyamide 6 (PA6) composites with tetra-needle-shaped zinc oxide whisker (T-ZnOw) are studied in this work. Two different silane coupling agents, KH-550 with amino groups and KH-560 with epoxy groups, are used to treat T-ZnOw. The results show that the coupling agent types, content as well as the T-ZnOw content have much influence on the impact fracture behaviors of T-ZnOw/PA6 composites. Compared with the composites filled with untreated T-ZnOw, in which the impact strength decreases linearly with the increasing content of filler, chemical treated T-ZnOw improves the impact strength of the composites apparently due to the improved interfacial interaction between T-ZnOw and matrix. Further results show that the main toughening mechanisms of treated T-ZnOw in PA6 composites include the pullout of T-ZnOw from matrix, the anchoring role of other three needles when one of the four needles of T-ZnOw is pulled out from matrix, and the local yielding or deformation of matrix around the T-ZnOw. [Copyright &y& Elsevier]

Abstract: In this work, multi-walled carbon nanotubes were successfully chemically modified by maleic anhydride (f-MWCNTs), and the f-MWCNTs were melt compounded with poly(ethylene terephthalate) (PET) by using a twin-screw extruder to prepare nanocomposites. The effects of f-MWCNTs on the crystallization behavior of PET nanocomposites were studied via DSC and POM. The results show the apparent nucleation effect of f-MWCNTs in PET crystallization. The cold-crystallization peak temperature decreases with the increase of f-MWCNTs during the heating process. On the other hand, the addition of f-MWCNTs can greatly enhance the melt-crystallization peak temperature of PET when it is cooled from the melt. The nonisothermal crystallization kinetics of PET with f-MWCNTs was analyzed by different methods and the results also prove that the f-MWCNTs clearly accelerate the crystallization process of PET. [Copyright &y& Elsevier]