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Bisphenol-A polycarbonate (PC) is an intrinsically crystallizable polymer. Its industrial parts, however, invariably remain in an amorphous state due to its extremely slow crystallization kinetics....

Poly(vinylidene fluoride) (PVDF) is rich in different polymorphs. Among them, β-phase PVDF is of technical importance because of its strong spontaneous polarization and desired piezoelectric proper...

In response to the stringent requirements for future DC-link capacitors in electric vehicles (EVs), it is desirable to develop dielectric polymer films with high-temperature tolerance (at least 105...

With the world’s focus on environmental and sustainability problems, bio-based polymer porous materials have achieved tremendous attention. Here, light weight and biodegradable cellulose/polylactic acid (PLA) porous biocomposites with outstanding mechanical and heat resistance properties are fabricated based on a novel template-directed strategy. The cellulose/PLA porous biocomposites exhibit densities as low as 0.09 g/cm3 and specific moduli as high as 288.9 MPa g−1 cm3. More importantly, the biocomposites possess a high service temperature of 221.3 °C after a thermal treatment, ascribing to the exclusive formation of stereocomplex crystals (SCs) in PLA with a high crystallinity of 0.5. In situ wide-angle X-ray diffraction observations reveal that cellulose templates significantly accelerate the nucleation of SCs without suppressing the growth, and thus greatly facilitate SC crystallization. The stimulation of SC nucleation lies in the interfacial hydrogen bonding interactions between cellulose templates and PLA molecules, which promote the formation of precursor racemic helical pairs. The current work provides further inspiration on fabricating bio-based polymer porous materials in a greener and more sustainable way.

Polylactide (PLA) films with an excellent balance of toughness and stiffness were realized by extensional stress efficiently. For the relatively low extensional stress, gauche–gauche conformers tha...

It is an effective strategy to improve the heat resistance of polylactide (PLA) via forming stereocomplex crystals (SCs) in poly( l -lactide) (PLLA)/poly( d -lactide) (PDLA) blend. In this work, pentearythritol (PENTA), which is an environment-friendly polyhydroxy compound for food packaging, is selected to facilitate the SC crystallization and suppress the HC crystallization for HMW PLLA/PDLA blend. Impressively, only 3 wt% PENTA is added, the exclusive SCs with high content (Xc,SC = 50%) can be obtained, which exhibits a high promotion efficiency of crystallization of SCs. Interestingly, with PENTA content ascending, the crystallinity of SCs increases drastically first and then in a relatively slow manner. Furthermore, Miscibility with high content of PENTA leads to a relatively looser packing of SC lamella in the blend confirmed by scanning electron microscope (SEM) due to intercalation of PENTA between crystal lamella. The mechanism of how PENTA facilitates the formation of SCs at molecular level is also proposed in this work.

Currently, many catalysts are inconvenient to separate from water, and the solvents used in the preparation process are not environmentally friendly, resulting in low recovery efficiency and secondary pollution. In this study, the magnetic and porous regenerated cellulose/carbon nanotubes/Fe3O4 nanoparticles (RC/CNTs/Fe3O4 NPs) composites were synthesized for activation of peroxydisulfate (PDS) in a green alkaline-urea system. The RC/CNTs/Fe3O4 NPs-PDS system achieved 100% removal of bisphenol A compared with CNTs (~64.6%), RC (~0%) or Fe3O4 NPs (~0%), which was closely related to the introduction of defects and functional groups, nitrogen doping and conductive networks. Interestingly, the strong interaction between CNTs and the sheath-like protective layer formed by urea on the cellulose surface promotes the introduction of nitrogen into the composites at the preparation temperature of 70 °C. Moreover, the mechanism of the system was found to be a typical non-radical pathway. Fortunately, there is no leaching of iron ions in the system, and the effects of the actual waterbody, initial pH, and different anions are negligible. The recycling and separation experiments revealed the practicality and superiority of the composite. This work provides a feasible and sustainable strategy for the application of natural cellulose-supported catalysts.

Lightweight conductive polymer composites based on biomass could be a promising candidate for electromagnetic interference (EMI) shielding application. Herein, tailoring porous microstructure and regulating the distribution of carbon nanotubes (CNTs) in cellulose composites are attempts to achieve highly efficient EMI shielding properties accompanying desired mechanical property and low density. Specifically, aligned porous structure is fabricated by ice-template freeze-drying method; meanwhile, CNT is regulated to decorate inside the cellulose matrix (CNT-matrix/cellulose porous composites) or to directly bind over the cellulose cell walls (CNT-interface/cellulose porous composites). It is found that, owing to the preferential distribution of CNT on the cell walls, the CNT-interface/cellulose porous composites possess a very high electrical conductivity of 38.9 S m-1 with an extremely low percolation threshold of 0.0083 vol % with regard to CNT-matrix/cellulose porous composites. Therefore, a shielding effectiveness of 40 dB with merely 0.51 vol % CNT under a thickness of 2.5 mm is achieved in CNT-interface/cellulose porous composites, which is attributed to efficient multiple reflections and the accompanying absorption with promoted conductivity and better-defined porous structure. More laudably, the CNT-interface/cellulose porous composites reveal a superior mechanical property with a specific modulus of 279 MPa g-1 cm3. The value behind the current work is to pave an effective way to fabricate environmentally benign, high-performance EMI shielding materials to practically boost numerous advanced applications of cellulose.

Halloysite (Hal), calcined Hal, and organosilane-modified Hal were used as filler for the preparation of Hal/PBAT nanocomposite. XRD, SEM, XPS, FTIR, DSC, POM, and Avrami, Jeziorny, Kissinger models were used to characterize the surface property of Hal and its effect on the crystallization morphology, structure and kinetics of nanocomposites. Hydrogen bonding, generated between NH2 or –OH groups on surface of organosilane-modified calcined Hal or calcined Hal and C (C O) O in ester of PBAT, efficiently enhanced the nucleation ability of Hal nanofiller, resulting in increment of crystallization temperature, decrease of half time, but retard the transport of PBAT molecules chains. The stronger the hydrogen bond was, the more remarkable such influence was. This study provides a promising approach of tailoring the surface characteristic of Hal to manipulate the crystallization of biodegradable aliphatic-aromatic polyesters, especially with extreme low loading of Hal nanofiller.

In this paper, a novel molecularly imprinted electrochemical sensor (MIECS) based on a glassy carbon electrode (GCE) modified with graphene quantum dots (GQDs) coated on hollow nickel nanospheres (hNiNS) for the rapid determination of bisphenol S (BPS) was proposed for the first time. HNiNS and GQDs as electrode modifications were used to enlarge the active area and electron-transport ability for amplifying the sensor signal, while molecularly imprinted polymer (MIP) film was electropolymerized by using pyrrole as monomer and BPS as template to detect BPS via cyclic voltammetry (CV). Scanning electron microscope (SEM), energy-dispersive spectrometry (EDS), CV and differential pulse voltammetry (DPV) were employed to characterize the fabricated sensor. Experimental conditions, such as molar ratio of monomer to template, electropolymerization cycles, pH, incubation time and elution time were optimized. The DPV response of the MIECS to BPS was obtained in the linear range from 0.1 to 50μM with a low limit of detection (LOD) of 0.03μM (S/N = 3) under the optimized conditions. The MIECS exhibited excellent response towards BPS with high sensitivity, selectivity, good reproducibility, and stability. In addition, the proposed MIECS was also successfully applied for the determination of BPS in the plastic samples with simple sample pretreatment.

Stereocomplex crystal (SC) formation induced by thermal treatment is the most promising approach to achieve the heat resistance of polylactides (PLA). However, a hierarchical morphology of SCs, formed under a different thermal environment, is rarely reported although it is crucial for us to understand their enhanced effect on heat resistance. This work examines the morphology of 1:1 stoichiometric blends of poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) after thermal treatment. In order to explore the formation mechanism of the morphology, in situ wide-angle X-ray diffraction (WAXD) was conducted during the entire thermal treatment. Interestingly, a phase separation structure resulting from the melt memory effect of homocrystallites is observed, for the first time, when the amorphous sample was treated at a relatively low temperature (190 °C). Upon increase of the treatment temperature to a medium one (210 °C), two template effects, that is, the template of unmelted SCs during the isothermal process and new ...

It is a great challenge to develop a feasible strategy for reconciling barrier performance and mechanical ductility of environmentally friendly poly(lactic acid) (PLA) in the application of packaging industry. In the current study, the combination of manipulating the amorphous chain entanglement network of PLA and constructing “dual barrier walls” of highly aligned GONSs and well-defined PLA crystals simultaneously enhanced barrier properties and ductility of PLA nanocomposite films via “biaxial stretching-constrained annealing” method. The intense extensional field during biaxial stretching induced highly aligned GONSs as the first barrier wall and regulated the amorphous chain entanglement network. Constrained annealing promoted the growth and perfection of PLA crystals as the second effective barrier wall and strengthened amorphous chain entanglement network to some extent. More interestingly, GONSs were first verified as contributors to stabilize the enhanced amorphous chain entanglement network of PLA and benefited for the mechanical ductility of PLA nanocomposite films. As a result, this synergetic structure manifested excellent comprehensive ability in ameliorating the intrinsic drawbacks of brittle and poor barrier PLA films, exhibiting low oxygen permeability coefficient of 0.712 × 10−14 cm3 cm cm−2 s−1 Pa−1, excellent ductility with elongation at break of 147.8%, high yield strength of 83.1 MPa and good dimensional stability with deformation ratio of as low as 3%. The as-prepared PLA nanocomposite films with excellent comprehensive properties hold great potential prospects in the application of packaging industry. The methodology proposed here opens up a new avenue to fabricate environmentally friendly PLA films for promoting the sustainable development of packaging industry.

Compared with complementary metal–oxide semiconductor (CMOS), the resonant tunneling device (RTD) has better performances; it is the most promising candidate for next-generation integrated circuit devices. The universal logic gate is an important unit circuit because of its powerful logic function, but there are few function synthesis algorithms that can implement an n-variable logical function by RTD-based universal logic gates. In this paper, we propose a new concept, i.e., the truth value matrix. With it a novel disjunctive decomposition algorithm can be used to decompose an arbitrary n-variable logical function into three-variable subset functions. On this basis, a novel function synthesis algorithm is proposed, which can implement arbitrary n-variable logical functions by RTD-based universal threshold logic gates (UTLGs), RTD-based three-variable XOR gates (XOR3s), and RTD-based three-variable universal logic gate (ULG3s). When this proposed function synthesis algorithm is used to implement an n-variable logical function, if the function is a directly disjunctive decomposition one, the circuit structure will be very simple, and if the function is a non-directly disjunctive decomposition one, the circuit structure will be simpler than when using only UTLGs or ULG3s. The proposed function synthesis algorithm is straightforward to program, and with this algorithm it is convenient to implement an arbitrary n-variable logical function by RTD-based universal logic gates.

Tailoring interfacial crystallization has been widely recognized as a promising pathway to enhance interfacial adhesion between a polymeric matrix and a reinforcing fiber. However, the induction ability of natural fiber is usually disturbed by an uneven internal structure. In this work, to encourage interfacial crystallization between ramie fiber (RF) and poly(l-lactic acid) (PLLA), stereocomplex (sc) crystallites were physically decorated on the surface of RF as nucleation promoters. Compared to the sparse spherulites dispersed around the raw RF, sc-coated RF fostered a well-defined transcrystallinity (TC). The nucleation sites on the surface of the decorated RF substantially increased with the thickness of sc coating, thus changing the contour of TC from a fan shape to a brush shape, while the growth rate of TC was dependent on the crystallization temperature. Given the primary credit to nucleation effect of sc coating, the TC generated in the PLLA/sc-coated RF composite showed notably higher overall cr...

A novel molecularly imprinted electrochemical sensor based on Fe3O4@Au nanoparticles immobilized on amine-multi-walled carbon nanotubes by the strong chemisorption had been developed for detecting dipyridamole (DIP) in human serum using precipitation polymerization method. DIP can be detected by this electrochemical sensor through the response current change before and after binding DIP with the formation of hydrogen bonds. The experimental binding data for this study was modeled with the Freundlich isotherm (FI) equation, demonstrating the high imprinting efficiency. The molecularly imprinted electrochemical sensor based on Fe3O4@Au-MWCNT nanocomposite amplifies the response current in differential pulse voltammetry measurement, allowing the detection limit reaching 0.03 ng mL−1 in a wide linear range from 0.5 to 1900 ng mL−1, which is remarkably better than those of currently used methods and the previous reports. Moreover, this molecularly imprinted electrochemical sensor has first been developed for the detection of DIP based on the Fe3O4@Au-MWCNT composite, which has a promising potential in the detection of DIP in human serum which enables low-cost, effective, and sensitive determination.

Poly-(butylene adipate-co-terephthalate) (PBAT) has captured significant interest by dint of its biodegradability, superb ductility, promising processing properties and good final properties, but the insufficient barrier performance limits its application, especially in packaging field. In the present work, improved barrier properties of PBAT films were obtained by introducing an extremely low amount of graphene oxide nanosheets (GONS). O2 and water vapor permeability coefficients were decreased by more than 70% and 36% at the GONS loading of 0.35 vol%, respectively. The enhanced barrier performance was ascribed to the outstanding impermeability and well dispersion of GONS as well as the strong interfacial adhesion between GONS and PBAT matrix. Furthermore, tensile strength and Young's modulus of GONS/PBAT nanocomposite rise up to 27.8 MPa and 72.2 MPa from 24.6 MPa to 58.5 MPa of neat PBAT, respectively, showing a prominent increase of mechanical properties compared to neat PBAT. The incorporation of GONS also endowed PBAT matrix with an excellent thermal stability. These findings provide a significant guidance for fabricating high barrier films on a large scale.

A unique oscillation shear injection molding was utilized to investigate the crystallization of poly ( l -lactide) (PLLA) under the coexistence of an intense shear flow and nucleating agents. The crystalline morphology and its distribution of injection-molded PLLA were probed by wide-angle X-ray diffraction, showing that an intense shear flow promotes the crystallization significantly, whereas the nucleation effect by nucleating agents is negligible. Additionally, applying an intense shear flow during injection molding processing at a low mold temperature makes PLLA form a crystalline layer structure, including skin, intermediate and core layers. Meanwhile, nucleating agents were found to play different roles in the crystallization of injection-molded PLLA under different processing conditions. The results of thermal mechanical property and Vicat softening temperature show the injection-molded PLLA sample with a thick crystalline layer structure has a greatly enhanced heat resistance property.

Stereocomplex crystals (SCs) of polylactides (PLAs) with melting points over 220 °C show great potential to improve the heat deflection resistance of PLAs. However, it is still a challenge to fabricate PLA materials with high SC contents due to the requirement for high production efficiency and thus an extremely large cooling rate. In the present work, an upgraded injection molding method, i.e., oscillation shear injection molding (OSIM), was employed to impose intense shear flow on poly(l-lactide) (PLLA)/poly(d-lactide) (PDLA) samples. It is proved that even though a large cooling rate existed, the intense shear flow provided by OSIM induced higher crystallinities of the SCs and well-defined lamellar structure in comparison with conventional injection-molded ones, which subsequently resulted in a high Vicat softening temperature (close to 200 °C) and superb heat deflection resistance in boiling water. To clarify the mechanism of shear-induced SC formation, in situ characterization with precisely controll...

Inferior water barrier performance has always been a major deficiency of polylactide (PLA) that is in practice difficult to overcome owing to the existence of plentiful hydrophilic ester bonds in the main chain. Here, we propose an architecture of super-hydrophobic 3D-networks in PLA, where interconnected graphene oxide grafted octadecylamine (GOgODA) nanosheets are able to effectively suppress dissolution and diffusion of water molecules into the PLA matrix. Prior to the employment of the special technology “decoration of building block for vapor barrier – post-molding assembly”, uniform-sized PLA microspheres and super-hydrophobic GOgODA were simultaneously prepared. Perfect GOgODA networks were successfully realized within transparent nanocomposite PLA films and obvious enhancement of the water barrier was prominently achieved. Specifically, a remarkable decrease of almost 6.5 times in water permeability coefficient was observed for the nanocomposite films containing a very small volume (0.268 vol%) of GOgODA (1.43 × 10−14 g cm cm−2 s−1 Pa−1) compared with pure PLA films (9.28 × 10−14 g cm cm−2 s−1 Pa−1). This prominent amelioration was derived from the ordered dispersion of well-extended GOgODA nanosheets, which concentrate selectively at the interface of PLA regions and are arranged exactly perpendicular to the permeating pathway of water molecules. This methodology provides a facile and effective way to advance the functions and properties of PLA.

Structuring nacre-mimetic superstructures during polymer melt processing could be a promising route to high performance structural materials with exceptional strength and toughness. A nacre-mimetic superstructure characterized with aligned lamellae (stiff phase) glued by amorphous polymer chains (soft and tough phase) was fabricated from a biodegradable polymer of poly(butylene succinate) (PBS) with favorable kinetics of crystallization by using an intense shear flow and promoted by natural ramie fiber. The well-aligned layered structure with a thickness of ∼90 nm for the stiff phase and ∼100 nm for the soft phase was identified with field-emission scanning electron microscopy, and the nacre-mimetic superstructure was quantitatively characterized by space-resolved small angle X-ray scattering. The thicknesses of crystalline lamellae and the amorphous phase layer between crystalline lamellae in the aligned layers were quantitatively assessed to be 3–4 nm and 4–6 nm respectively, indicating that multilayered crystal stacks are formed in the stiff phase. The nacre-mimetic superstructure leads to highly effective load transfer between the stiff phase and soft phase. Thus, the nacre-mimetic superstructure in PBS and the PBS/ramie fiber biocomposite shows simultaneous enhancement in strength and toughness in comparison to common materials without aligned layered structures. Our findings highlight the significance of nacre-mimetic superstructures in polymeric materials and provide novel prospects for the structuring of polymeric materials during melt processing.

Hybrid systems integrating carbon nanotubes (CNTs) with cellulose showcase several key properties that can address emerging multifunctional needs, such as good electrical conductivity and electromagnetic interference (EMI) shielding. Herein, a subtle approach is accordingly developed to prepare CNTs/cellulose composite films that feature a layered structure consisting of a poly(ethylene oxide) (PEO)/CNTs layer as the EMI shielding layer and a regenerated cellulose layer as the supporting substrate. PEO acts as a robust enhancer of interfacial adhesion between the CNTs and the cellulose layers due to its favorable compatibility with cellulose chains, which is effective to prevent deterioration of the mechanical properties of the material; moreover, the high content of CNTs with trace amounts of PEO shows an extremely high electrical conductivity of 20 S cm−1. The layer-structured film shows an extremely high electrical conductivity of 20 S cm−1 and an excellent EMI shielding effectiveness (SE) of above 35 dB in the X-band, together with high tensile strength and a Young's modulus of 26.9 and 2615.4 MPa, respectively. Moreover, the composite shows extremely high specific SE (up to 1372.4 dB cm2 g−1) – an unprecedented result for CNT/cellulose materials. Comparatively, a plain-structured composite counterpart prepared via the normal direct-mixing process exhibits a much lower electrical conductivity of 2 S cm−1 and an inferior EMI shielding performance of 20 dB. Furthermore, the plain-structured composite suffers profound deterioration in mechanical strength and Young's modulus (12.4 and 1274.3 MPa, respectively). The film thickness and number of conducting layers significantly influence the EMI shielding performance, which indicates tunable EMI SE for this composite. Specifically, an increase in the total thickness leads to ultrahigh SE exceeding 65 dB. Although they have the same total thickness as monolayer films, a distinct enhancement in EMI SE for the multilayer films is clearly demonstrated, driven by the coherent multiple reflections at the internal interfaces of the conductive and cellulose layers. This study may provide a broader context for exploiting cellulose-based composite films with tunable electromagnetic interference shielding effectiveness; these films may find applications in portable electronic devices and radiation sources.

Cellulose films are of poor water-vapor barrier performance. Herein, we put forward an effective way to suppress adsorption by crosslinking of hydroxyl groups via epichlorohydrin (ECH), meanwhile graphene oxide (GO) nanosheets are utilized to prolong the pathway of vapor penetration. The strategy confers a significant enhancement of vapor barrier performance as well as mechanical properties to cellulose-based films. Specifically, an outstanding reduction of 67.4% in water-vapor permeability coefficient is achieved in nanocomposite films compared to the uncrosslinked cellulose films. Furthermore, for the first time, two-dimensional correlation analysis reveals that crosslinking of ECH do not alter penetration direction, while GO can eminently act as shielding for the formation of bound water which change the sequential order of firstly-interacted vapor area from crystalline to amorphous area. Free volume is the penetration destination. The retarding effect introduced by the GO in amorphous area gives rise to the improvement of the vapor-barrier.

Superhydrophobic electromagnetic interference (EMI) shielding textile (EMIST) is of great significance to the safety and long-term service of all-weather outdoor equipment. However, it is still challenging to achieve long-term durability and stability under external mechanical deformations or other harsh service conditions. Herein, by designing and implementing silver nanowire (AgNW) networks and a superhydrophobic coating onto a commercial textile, we demonstrate a highly robust superhydrophobic EMIST. The resultant EMIST shows a synergy of high water contact angle (160.8°), low sliding angle (2.9°), and superior EMI shielding effectiveness (51.5 dB). Remarkably, the EMIST still maintains its superhydrophobic feature and high EMI shielding level (42.6 dB) even after 5000 stretching-releasing cycles. Moreover, the EMIST exhibits strong resistance to ultrasonic treatment up to 60 min, peeling test up to 100 cycles, strong acidic/alkaline solutions, and different organic solvents, indicating its outstanding mechanical robustness and chemical durability. These attractive features of the EMIST are mainly a result of the joint action of AgNWs, carbon nanotubes, polytetrafluoroethylene nanoparticles, and fluoroacrylic polymer. This work offers a promising approach for the design of future durable, superhydrophobic EMISTs, which are capable of remaining fully functional against long-time exposure to extreme conditions, for example, wet and corrosive environments.

During polymer processing, the polymeric blends are inevitably subjected to coupled external fields (flow, pressure, and temperature), which have great effects on the phase behavior, crystallization behavior, crystalline structure, and final properties of blends. A typical crystalline/amorphous miscible blend system, poly(vinylidene fluoride)/Poly(methyl methacrylate) (PVDF/PMMA) blend, is chosen to understand the coupling effect of processing fields on crystallization behavior of the blends. It is found that shear flow can induce locally oriented trans conformation, which finally transforms into polar β/γ phases during isothermal crystallization under pressure. Interestingly, under pressure, β and γ phases exhibit different sensitivities to shear rate. The γ phase is easily formed at low shear rate, while higher shear rate is required to induce β phase formation, which could be related to the sequence length of the oriented trans conformation induced by shear flow. As for the addition of PMMA, the hydrogen bonding interactions between carbonyl groups of PMMA and hydrogen atom of PVDF could stabilize the shear-induced local trans conformation and subsequently lead to more β/γ phases. Meanwhile, different from PVDF crystallized under static condition, the shear flow and PMMA synergistically induce the transformation from spherulitic to shish-kebab-like structure and highly oriented thick β phase with higher melting point. To the best of our knowledge, it is the first time to reveal the unique crystallization behaviors of PVDF/PMMA blends induced by flow field coupled with pressure. This work could provide a significant guidance for the control of crystal polymorphs of PVDF/PMMA miscible blends during processing.

A novel sensing system was constructed by biomass carbon/MOF-derived Co3O4/FeCo2O4 (BC/Co3O4/FeCo2O4) composite decorated with glassy carbon electrode (GCE) for exploiting to determine dopamine (DA), acetaminophen (AC), and xanthine (XA) simultaneously. The BC/Co3O4/FeCo2O4 composite was synthesized via a facile in-situ growth process and calcination treatment, coupled with hydrothermal reaction. This composite could appreciably enlarge the electrochemically active surface area of as-prepared sensor to promote electron transfer resulting in enhanced response signals. Applying BC/Co3O4/FeCo2O4/GCE sensor under the optimum conditions, the differential pulse voltammetry (DPV) current responses vs. concentration are linear in the wider ranges of 0.1–250 μM, 0.1–220 μM, and 0.5–280 μM, along with low detection limits (LOD, S/N = 3) of 0.04587 μM, 0.02886 μM, and 0.1209 μM for DA, AC and XA correspondingly. Moreover, the proposed sensor exhibited a satisfying selectivity, stability and reproducibility as well. Finally, this sensor had been utilized to detect DA, AC and XA successfully in real samples with satisfactorily apparent recoveries, providing a promising application for further sensing analysis.

Cellulose, as the most abundant natural polymer material on the earth, has attracted worldwide attention due to its characteristics of reproducibility, universality, low cost, biocompatibility and biodegradability. Cellulose-based materials have potential value in supercapacitors, environment and biomedicine. The combination of cellulose and carbon materials can further adjust the microstructure of the composite such as porosity (76–98.8%) and specific surface area (5.07–47.3 m2/g), and enhance the properties of the composite such as the adsorption rate (47–100%) and the degradation rate of pollutants (60–100%), the Young's modulus (1.14–16.6 GPa) and the tensile strength (23.1–277.5 MPa). Besides, composites have the advantages of high electronic transmission efficiency and good reusability, which broaden their applications in water treatment. This review summarizes the molding methods of multi-dimensional cellulose materials, as well as the development status, preparation and modification methods of composites formed by carbon materials such as graphene, carbon nanotubes, activated carbon and nanodiamonds with cellulose, analyzes the research progress and existing problems of the composites in water treatment fields such as adsorption, catalysis, membrane separation and microbial fuel cells, and finally, we make some perspectives for the future researches and applications.

Al-Li 2198-T8 alloy sheet was processed by friction spot welding (FSpW). The microstructures and tensile properties of FSpW 2198-T8 alloy were studied by means of optical microscopy (OM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results show that the grain size of Al-Li 2198-T8 alloy processed by FSpW was refined with the strengthening precipitates dissolved into Al matrix and dislocation density decreased. Hence, the plasticityin thermo-mechanical coupling zone (TMCZ) of FSpW 2198-T8 alloy was improved, while the yield strength (YS) of TMCZ zone was lower than the original material (239 MPa

Stereocomplex (sc) crystallization is appealing to endow the poly( l -lactic acid)/poly( d -lactic acid) (PLLA/PDLA) blends with superior heat resistance. However, sc formation is dampened in the high-molecular-weight (HMW) racemic blends. Here, we disclosed a simple but effective approach to facilitate sc formation by introducing carbon nanotubes (CNTs) during the solution casting. As revealed by wide-angle X-ray diffraction and differential scanning calorimetry, the HMW equimolar PLLA/PDLA blends were overwhelmingly crystallized into sc modification in presence of a small amount of CNT, and the relative content of homocrystallites was notably decreased. Especially, exclusive formation of sc crystallites was found with only incorporation of 0.2 wt% CNTs. Such an intriguing phenomenon was probably attributed to the fact that CNTs acted as the anchor to promote intermolecular nexus and triggered the headmost crystallization between PLLA and PDLA.

In order to obtain white light-emitting materials, the luminescent glasses composed of SrO–ZnO–TiO2–P2O5 co-doped with Tm3+ and Dy3+ ions were synthesized by a conventional melting-quenching method. The luminescent properties of Tm3+ and Dy3+ in zinc strontium phosphate glasses were investigated, where the emission spectra show possible energy transfer mechanism between Tm3+ and Dy3+ ions. The energy transfer carries out via resonant transfer modes, which is easily understood from Tm3+ and Dy3+ energy level diagrams. The decreasing in mean-duration time of Tm3+:1D2 and Dy3+:4F9/2 obtained from the decay curves makes a further evidence of energy transfer from Tm3+ to Dy3+ ions and Dy3+ to Tm3+ ions in the glasses.

A novel dual-edge implicit pulse-triggered flip-flop with an embedded clock-gating scheme (DIFF-CGS) is proposed, which employs a transmission-gate-logic (TGL) based clock-gating scheme in the pulse generation stage. This scheme condi- tionally disables the inverter chain when the input data are kept unchanged, so redundant transitions of delayed clock signals and internal nodes of the latch are all eliminated, leading to low power efficiency. Based on SMIC 65 nm technology, extensive post-layout simulation results show that the proposed DIFF-CGS gains an improvement of 41.39% to 56.21% in terms of power consumption, compared with its counterparts at 10% data-switching activity. Also, full-swing operations in both implicit pulse generation and the static latch improve the robustness of the design. Thus, DIFF-CGS is suitable for low-power applications in very-large-scale integration (VLSI) designs with low data-switching activities.

Isotactic polypropylene (iPP) composites with carbon nanotube (CNT) networks at relatively high loadings could have various applications such as electromagnetic interference shielding and thermal conductivity. The crystallization behavior of iPP inside CNT networks could be very much related to the above properties, which was found to be quite different from that of neat iPP in this work. In CNT networks, CNTs not only act as effective heterogeneous nucleating agents to noticeably increase the onset temperature (more than 18°C) of iPP crystallization but also bring strong confinement on the mobility of iPP chains and then reduce the overall crystallization rate of iPP matrix. It is interesting to find that CNT networks, especially in the case of ultrahigh loading (90 wt%), have remarkable confinement effect on crystallization of iPP, overcoming the heterogeneous nucleation of CNTs, resulting in a decline of crystallization rate of iPP. The nonisothermal crystallization kinetics of iPP in the dense CNT network quite fits to the modified Avrami mode by Jeziorny, even more satisfactorily than the case of neat iPP. When confinement effect is dominated during crystallization, we found that the perfection and size of crystallites are extremely decreased at ultrahigh loading, leading to a very low melting point of iPP (approximately 140°C).

Developing a sustainable and environmently friendly scheme to fabricate fully degradable barrier films with robust mechanical properties is still a great challenge. Here, we first put forward a methodology that through taking advantage of an elongational flow field followed by woven hot compaction, in situ nanofibrillar networks of polylactide (PLA) are creatively constructed within a poly(butylene succinate) (PBS) matrix serving as an efficient “barrier ball” and reinforcement. The in situ PLA nanofibrils tend to overlap to constitute into a kind of interwoven network, in which highly oriented PLA lamellae are regularly arranged. Simultaneously, this network produces a spatial confinement effect on the crystallization of PBS, resulting in a confined environment around the nanofibrillar networks. This unparalleled hierarchical structure can availably attribute to an exceptional gas barrier and mechanical properties of the composite films. Ultimately, the oxygen permeability coefficient of the composite fi...

Peculiar oriented β-crystals with its c-axis perpendicular to the injection molding direction were formed in the injection molding processing. Simultaneous with the uniaxial elongation, in situ synchrotron X-ray scattering was employed to investigate the influence of oriented β-crystals on the deformation behavior of the skin and core layers of the injection-molded parts. The presence of oriented β-crystals accelerated the appearance of the yield point, and the yield point became the transition point from lamellar slip to fragmentation. Oriented β-crystals with more regular orientation in the skin layer were favorable for the earlier occurrence and delayed enlargement of microvoids. The formation of microvoids under loading turned out to be related with the separation or slip of oriented β-crystals, which is earlier than the destruction of β-crystals (β-α polymorphous transformation).

In this work, we demonstrate that utilization of extensional flow with different intensities can regulate the flow-induced crystallization and epitaxially surface-induced crystallization simultaneously in crystalline–crystalline immiscible blends, leading to improved interfacial adhesion and thus enhanced mechanical properties, which provides a versatile methodology to industrially achieve polymer blends with advanced performance. An accessible methodology, i.e., “extrusion–hot stretching–quenching”, was applied to fulfill the scalable achievement of an epitaxial interface for a linear low density polyethylene (LLDPE)/isotactic polypropylene (iPP) blend, where LLDPE could epitaxially grow on an oriented iPP substrate but greatly influenced by the flow field, with its chains and lamellae aligned abnormally off the flow direction revealed by wide angle X-ray diffraction and small angle X-ray scattering, respectively. Depending on the intensity of flow, the above effect of flow can be divided into two types: under a strong flow field, the LLDPE chains prefer to align along the flow direction, inducing the formation of a shish-kebab structure. For another type, i.e., under a weak flow field, the pre-oriented LLDPE chains can relax quickly and epitaxially nucleate on the surface of the oriented iPP substrate. During further growth, the epitaxial LLDPE lamellae deform and reorient along the flow direction under the mechanism of flow-induced block slips, fragmentation and reorientation. Moreover, it is believed that incomplete lamellar twist also occurs under flow. Mechanical property tests demonstrate that an epitaxial structure significantly improves the interfacial adhesion between LLDPE and iPP, showing remarkable enhancements in both strength and toughness.

Understanding crystalline morphology and crystallization kinetics of PBS in the presence of a nanoclay is crucial to reveal the relationship between properties, morphology, as well as the processing of PBS/clay nanocomposites. In this work, two types of organoclay with slightly different polarity are homogeneously dispersed in PBS by melt intercalation. Interestingly, the crystallization kinetics of poly(butylene succinate) (PBS) are seriously affected by this slightly different polarity of the organic modifier grafted nanoclay. During isothermal crystallization of PBS in the presence of an organoclay, the crystallization behavior is significantly confined by an organoclay with slightly stronger polarity compared to that of an organoclay with a relatively weak polarity. Further, the nucleation density and crystallinity of PBS in the presence of 20 wt% of an organoclay with slightly stronger polarity are separately decreased 48.8% and 13.4% compared to neat PBS, while another organoclay with weak polarity facilitates nucleation and has a negligible influence on crystallinity. This study offers a new insight into the effect of the organic modifier polarity of a nanoclay on the confined crystallization of PBS, which provides significant guidance for fabricating a high barrier PBS film by using confined crystals as reported in our previous work.

In this work, the growth dependence of oriented β-crystals in isotactic polypropylene (iPP) including their content, orientation and lamellar structures on the thermal treatment temperature (i.e. the final fusion temperature) is first investigated by in situ synchrotron X-ray diffraction/scattering. Interestingly, the dominance of oriented β-crystals is replaced by random α-crystals when the thermal treatment temperature in the range from 155 °C to 170 °C. This phenomenon is closely related to the nucleation efficiency of locally ordered domains of α-crystal and the template effect of residual α-crystals. Locally ordered domains of α-crystal are originated from the melting of β-crystals or (the partial melting of) α-crystals and β-α phase transformation. The orientation degree and lamellar structures of oriented β-crystals vary dramatically only when the thermal treatment temperature far exceeds the melting temperature of α-crystals. Comparably, the heat resistance of oriented β-crystals is stronger than the normal random ones.

Regenerated cellulose (RC) films exhibit poor water barrier performance, which seriously restricts its applications. To address this issue, an impermeable and hydrophobic graphene oxide modified by chemically grafting octadecylamine (GO-ODA) was utilized to enhance the water vapor barrier performance of RC nanocomposite films. Compared to the neat RC film, more than 20% decrease in the coefficient of water vapor permeability (PH2O) was achieved by loading only 2.0 wt % GO-ODA. The promising hydrophobicity of GO-ODA effectively retarded the formation of hydrogen bonding at the relatively weakened interface between GO and RC, compensating for the diffusion of water vapor molecules at the interface; on the other hand, the fully exfoliated GO-ODA nanosheets were inclined to align with the surface of the as-prepared RC nanocomposite films during hot-pressure drying, creating a much more tortuous pathway for diffusion of water molecules. The new insights could be valuable for widening application of cellulose such as packaging.

Crop area information can provide decision support for agricultural production management, and it is an important basis for formulating grain policy and economic plan. Remote sensing has an irreplaceable role in large-scale agricultural monitoring, in which optical remote sensing is greatly influenced by cloud and rain weather. It is often unable to obtain clear and clear optical remote sensing images in the critical period of crop growth, which seriously images the accuracy and timeliness of the classification of crop remote sensing. Synthetic aperture radar (SAR) capable of monitoring ground objects throughout the day and all weather, Polarimetric SAR data also include scattering matrix, geometric details and permittivity information, it is sensitive to the geometry and height of vegetation, which can make up for the lack of optical remote sensing and has unique advantages in crop identification and monitoring. So full polarization SAR has wide application demand and great potential in crop remote sensing monitoring. The effective use of full polarimetric SAR data to classify crops is of great academic and practical value for promoting the greater role of radar technology in national agricultural remote sensing monitoring and agricultural supply side structural reform. This paper summarizes the different data types and polarization decomposition methods of polarization SAR used in crop identification. According to the current research, there are the following deficiencies: first, most of the research subjects are rice, and dry land crops are less studied. Secondly, the identification of dry land crops is not accurate enough, and the average recognition accuracy is less than 85%. Finally, there are few researches on the scattering mechanism, which leads to poor rationality and poor universality. First, determine the scattering mechanism of dry land crops, and use scattering mechanism to improve the accuracy and universality of remote sensing recognition of dryland crops. Second, how to make use of the special imaging method of SAR to optimize the design is applicable to polarimetric SAR classification algorithm. Third, how to better integrate with optical remote sensing and other multi-source data, these three points will become the key problem to be solved in polarimetric SAR crop classification in the future.

Manipulating polymorphism in extended chain-crystals (ECCs), which are commonly achieved by crystallization under high pressures, is important for enriching our understanding of basic polymer crystallization as well as for achieving high performance materials. In this study, the influence of high pressure and ion–dipole interaction on the polymorphism was investigated by comparing neat poly(vinylidene fluoride) (PVDF) and PVDF with 1 wt % cetyltrimethylammonium bromide (CTAB) nonisothermally crystallized from the melt at 210 °C. Under low pressures (≤10 MPa), γ folded-chain crystals (FCCs), rather than α FCCs, were obtained for PVDF/1 wt % CTAB because of the ion–dipole interaction. Under a moderate pressure (100 MPa), pure β FCCs were formed in PVDF/1 wt % CTAB, owing to the synergistic effect of both high pressure and ion–dipole interaction. Under high pressures (≥200 MPa), mixtures of β/γ FCCs and ECCs were obtained for PVDF/1 wt % CTAB. This was different from the neat PVDF, where mixtures of α FCCs a...

Herein, a feasible protocol of nanohybrid shish kebab (NHSK) in isotactic poly(propylene) (iPP)/low density polyethylene (LDPE) blend is shown, where iPP nanofibrils in situ generate during melt compounding followed by hot stretching, thus serving as shish to induce the kebabs of LDPE under extensional flow, therewith leading to greatly improved mechanical properties. Although scanning electron microscope and small angle X-ray scattering results reveal classic characteristic of NHSK, wide angle X-ray diffraction demonstrates that some LDPE chains within the kebabs of LDPE are actually tilted off the flow direction. Through the comparison of LDPE lamellae epitaxially growing on iPP nanofibrils substrate under quiescent condition, it is concluded that the extensional flow affects the formation of NHSK notably, mainly by enhancing nuclei density and further influencing the twist of LDPE lamellae. Moreover, of particular significance is the methodology based on practical processing of extrusion in this work, making it promising to industrially achieve NHSK in polymer blend with advanced performance.

The microstructure and hardness of the stir zone (SZ) with different welding heat inputs were investigated for friction stir-welded 2024-T3 aluminum by transmission electron microscopy, differential scanning calorimeter and Vickers micro-hardness test. The results show that welding heat input has a significant effect on the hardness of the SZ. Under high welding heat input condition, a higher welding speed is beneficial for improving the hardness of the SZ. However, when the welding heat input is low, the hardness of the SZ elevates with increasing the rotation speed. The hardness of the SZ decreases after post-welded heat treatment due to overaging. The joints welded at 500 r/min and 100 mm/min show a high resistance to overaging. The reduction of hardness in the SZ is only 3.8%, while in other joints, the reduction is more than 10%. The morphology of strengthening precipitates plays important roles for the improvement of hardness.

The traditional approach toward barrier property enhancement of poly(lactic acid) (PLA) is the incorporation of sheet-like fillers such as nanoclay and graphene, unfortunately leading to the sacrificed biocompatibility and degradability. Here we unveil the first application of a confined flaking technique to establish the degradable nanolaminar poly(butylene succinate) (PBS) in PLA films based on PLA/PBS in situ nanofibrillar composites. The combination of high pressure (10 MPa) and appropriate temperature (160 °C) during the flaking process desirably enabled sufficient deformation of PBS nanofibrils and retention of ordered PLA channels. Particularly, interlinked and individual nanosheets were created in composite films containing 10 and 20 wt % PBS, respectively, both of which presented desirable alignment and large width/thickness ratio (nanoscale thickness with a width of 428±13.1 and 76.9±8.2 μm, respectively). With the creation of compact polymer "nano-barrier walls", a dramatic decrease of 86% and 67% in the oxygen permeability coefficient was observed for the film incorporated with well-organized 20 wt % PBS nanosheets compared to pure PLA and pure PBS (1.4 and 0.6×10(-14) cm3·cm·cm(-2)·s(-1)·Pa(-1)), respectively. Unexpectedly, prominent increases of 21% and 28% were achieved in the tensile strength and modulus of composite films loaded 20 wt % PBS nanosheets compared to pure PLA films, although PBS intrinsically presents poor strength and stiffness. The unusual combination of barrier and mechanical performances established in the fully degradable system represent specific properties required in packaging beverages, food and medicine.

Following our previous work on graphene oxide-induced polylactide (PLA) crystallization [Macromolecules 2010, 43, 5000-5008], in the current work, we further revealed the role of size and structural integrity of thermally reduced graphene oxide (RGO) in PLA crystallization. RGO nanoplatelets with different architectures were obtained via bath and probe ultrasound (RGOw and RGOp). The average size of RGO decreased substantially with ultrasound intensity and time, where the generation of RGO edges constituted the translocation of functional group sites from in-plane to edges. The formation of sp(3)-configuration dominated in RGOw, whereas the partial recovery of sp(2)-configuration occurred in RGOp, giving rise to either the escalation of sp(3)/sp(2) ratio for RGOw or retrogradation of that for RGOp. Isothermal crystallization kinetics of PLA nanocomposites containing RGOw and RGOp was determined by in situ synchrotron wide-angle X-ray diffraction. The induction period and overall crystallization rate of PLA/RGOw nanocomposites were strengthened with diminishing platelet size because of more nucleation sites encouraged by redistribution of functional groups. However, the adverse situation was found in PLA/RGOp nanocomposites. The observed phenomenon was ascribed to the disruption of the internal structure, i.e., the C═C sp(2) π-bond network, which deteriorated the CH-π interaction between PLA and RGO. These results conclusively suggested that the size and structural integrity of RGO had a concerted effort to determine the final nucleation ability of RGO dispersed by ultrasound.

The crystallization behavior of poly(butylene succinate) (PBS) nanocomposites with a wide range of contents of clays was revealed. It was of interest to find that the crystallization rate of PBS was accelerated obviously at relatively low contents of clays; while a retarded crystallization kinetics and a decreased crystallinity of PBS were found in the nanocomposites with higher clay contents. Two interplaying effects existed in the nanocomposites, i.e., a suppression effect of clays on nucleation and a templating effect of clays on crystal growth, were clarified to contribute to this intriguing crystallization behavior.

Carbon nanotube (CNT)/cellulose nanocomposite films were prepared by a featured processing method, i.e., solution dispersion, slow gelation and hot-press drying, where an environmentally benign processing solvent (sodium hydroxide/urea aqueous solution) was used. The scanning electron microscopy and transmission electron microscopy demonstrated uniform CNT dispersion in the cellulose. The slow gelation and hot-press drying could effectively reduce the free volume and force the cellulose chains and CNTs to contact as close as possible, thus forming the strong interfacial hydrogen bonding between the residual oxygen-containing functional groups on the CNT surfaces and the hydroxyl groups in the cellulose chains, as confirmed by X-ray photoelectron spectroscopy and Fourier transformation infrared spectroscopy results. As a result, with a CNT loading of 5 wt %, the tensile strength and Young’s modulus of the cellulose nanocomposite films were increased by 55% and 21% relative to neat cellulose film. More inte...

The paper makes the simulation and analysis to the power harmonic which is produced by the AC drive device of the hot strip mill in the background of the metallurgical industry. Aiming at the line-side effects of AC-AC frequency conversion and AC-DC-AC frequency conversion control system harmonic, the paper makes the MATLAB simulation and analysis in three circumstances, such as the load parameters, the inductance value changes of transformer primary side and secondary side, and adding reactor etc., and defines the functions and value ranges of the line reactor. The simulation results can provide a design basis for the harmonic control and the power supply system when the system uses the variable frequency devices, and then improves the power supply quality of the large drag device.

Reduced graphene oxide (rGO)/MnO 2 composites were synthesized by a facile one-step hydrothermal reaction of GO and KMnO 4 in ammonia solution, and then used as electrode materials for supercapacitors containing electrolytes of 1 M Na 2 SO 4 aqueous solution. The structures and morphologies of composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectra and N 2 adsorption–desorption isotherms. To assess the supercapacitive performances of these materials, cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy tests of two-electrode supercapacitors were performed. GO was reduced to form rGO and 30–50 nm sized MnO 2 nanoparticles were in-situ grown on the rGO sheets to obtain rGO/MnO 2 composites simultaneously during the hydrothermal reaction. The influences of mass ratios of GO and KMnO 4 on the electrochemical performances of supercapacitors were investigated. In comparison with pure MnO 2 -based supercapacitor, supercapacitors based on rGO/MnO 2 composites show better performances because both the specific surface areas and the electrical conductivities of electrode materials were increased by the introduction of rGO. When the mass ratio of GO and KMnO 4 is 2:1, rGO/MnO 2 composite electrode shows the highest capacitance of 205.7 F/g at a constant current density of 0.15 A/g in a two-electrode supercapacitor. Additionally, the supercapacitor exhibits high rate capability and long cyclic durability.

The polymorphic γ poly(vinylidene fluoride) (PVDF) induced by an ionic surfactant, cetyltrimethyl ammonium bromide (CTAB), is studied by using time-resolved Fourier transform infrared (FTIR) and two-dimensional (2D) correlation analysis. It is found that an extremely low content of CTAB can effectively induce γ PVDF due to the existence of strong ion-dipole interactions. Five stages are identified and intensive information on the growth and phase transition of α and γ phases in each stage is offered. Specifically, an induction periods observed for both α and γ phases in the stage I. In stage II, the α phase is initiated while the γ phase is still in the induction period, i.e., the nucleation and development of α phase are prior to the γ phase, although the resultant sample presents exclusively pure γ phase. The nucleation effect of CTAB for the γ phase is triggered in stage III, but α phase still grows faster than that of γ phase. Incorporating more CTAB impedes the growth of α phase while accelerates the development of γ phase. In stage IV, an α–γ phase solid transition accompanies the melt crystallization of the γ phase, and the α–γ phase transition is accelerated by CTAB molecules dramatically. Finally, the melt crystallization of the γ phase is completed, only α–γ phase transition is observed. This effort indicates that the pure γ phase of PVDF induced by ion-dipole interactions could originate from multiple phase behaviors, which could be helpful for understanding and manipulation of PVDF polar phases.

Poly(lactic acid) (PLA) is undoubtedly the most suitable for the environmentally friendly biodegradable packaging film due to its excellent integrated performances, but the insufficient gas barrier performance is its weakness. In the present work, graphene oxide nanosheets (GONSs) were fully exfoliated and randomly dispersed in the PLA matrix. A large decline in gas permeability coefficients of PLA films was obtained, where both O 2 and CO 2 permeability coefficients were respectively decreased by about 45% and 68% at a low GONS loading of 1.37 vol%. The enhanced gas barrier performance was ascribed to the outstanding impermeable property of GONSs as well as the strong interfacial adhesion between GONSs and PLA matrix, rather than the changes in crystallinity and crystalline structure of PLA matrix as demonstrated by the scanning electron microscopy, two-dimensional wide angle X-ray diffraction, and differential scanning calorimetry results. Meanwhile, the incorporation of GONSs could effectively block the transmission of UV light in the nanocomposite films and endow PLA matrix with an excellent thermal stability. These results suggest the potential application of GONS/PLA films as packaging materials for protecting perishable goods vulnerable to degradation from O 2 or high-energy light. And the new insight into the contribution of randomly dispersed GONSs to gas barrier properties of the semicrystalline polymer provides a significant guidance for fabricating high barrier films on a large scale in the packaging industry.