New Carbon Materials最新文献

A study of the interfacial behavior and internal thermal stress distribution in fiber-reinforced composites is essential to assess their performance and reliability. CNT/carbon fiber (CF) hybrid fibers were constructed using electrophoretic deposition. The interfacial properties of CF/epoxy and CNT/CF/epoxy composites were statistically investigated and compared using in-situ thermal Raman mapping by dispersing CNTs as a Raman sensing medium (CNTR) in a resin. The associated local thermal stress changes can be simulated by capturing the G‘ band position distribution of CNTR in the epoxy at different temperatures. It was found that the G‘ band shifted to lower positions with increasing temperature, reaching a maximum difference of 2.43 cm⁻¹ at 100 °C. The interfacial bonding between CNT/CF and the matrix and the stress distribution and changes during heat treatment (20–100 °C) were investigated in detail. This work is important for studying thermal stress in fiber-reinforced composites by in-situ thermal Raman mapping technology.

Low-rank coals are highly regarded as valuable precursors for carbon materials because of their ample reserves, high levels of polycyclic aromatic hydrocarbons, substantial carbon content and cost-effectiveness. Nevertheless, challenges in precisely manipulating the structure and characteristics of carbon materials derived from low-rank coals stem from the differences in ash content, microstructure, and interfaces across various low-rank coal sources. Recent research has provided strategies for governing the microstructure and surface attributes of carbon materials derived from low-rank coals. This review provides an overview of strategies for the preparation of adsorption active carbon, capacitive carbon, hard carbon, graphite and nano-carbon materials from low-rank coals. It also examines the influence of coal type and processing techniques on the microstructure, interface properties and functional group in them. The applications of coal-derived carbon materials in adsorption, supercapacitors, and alkali metal batteries are explored, and potential avenues for future research and its challenges are considered.

A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications. We investigated, the toughening effects of phenolphthalein-based cardo poly (ether sulfone) (PES-C) on E51/ DETDA epoxy and its carbon fiber composites (CFCs). Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island (of dispersed phase) structures to bi-continuous structures (of the matrix) as the PES-C content increased, which is associated with reaction-induced phase separation. After adding 15 phr PES-C, the glass transition temperature (Tg) of the blends increased by 51.5 °C, and the flexural strength, impact strength and fracture toughness of the blends were improved by 41.1%, 186.2% and 42.7%, respectively. These improvements could be attributed to the phase separation structure of the PES-C/epoxy system. A PES-C film was used to improve the mode-II fracture toughness (G_IIC) of CFCs. The G_IIC value of the 7 μm PES-C film toughened laminate was improved by 80.3% compared to that of the control laminate. The increase in G_IIC was attributed to cohesive failure and plastic deformation in the interleaving region.

A transformation of naphthalene-based coalescenced mesophase pitch (NMP) to mesophase microbeads was achieved by heating a mixture of NMP and fullerene (C₆₀). This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100% anisotropic bulk mesophase, but rather a reverse transformation. The effects of C₆₀ loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron microscopies. The physical changes in the NMP induced by C₆₀ were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffractometry and Raman spectroscopy. The results show that the coalesced NMP can be converted to a spherical type at 300–320 °C with the addition of 5% C₆₀, and the size of the mesophase microbeads increases with increasing temperature. Furthermore, a model is established to explain the unique induction effect of C₆₀ in the transformation process. This work makes the morphological transformation of MP controllable, and provides a new idea for the understanding and research of mesophase pitch.

Interfacial adhesion between carbon fibers (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. It is therefore of great importance to impregnate the CF bundles with PEKK as efficiently as possible. We report that PEKK with a good dispersion in a mixed solution of 4-chlorophenol and 1,2-dichloroethane can be introduced onto CF surfaces by solution impregnation and curing at 280, 320, 340 and 360 °C. The excellent wettability or infiltration of the PEKK solution guarantees a full covering and its tight binding to CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. The interior of the CF bundles is completely and uniformly filled with PEKK by solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS reached 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the formation of amorphous PEKK in the small spaces between CFs.

The preparation of a synthetic pitch from aromatic monomers could easily regulate structure orientation at the molecular level, which would be useful in fabrication. An isotropic synthetic pitch was prepared by a chlorine- and/or nitrogen-induced substitution polymerization reaction method using aromatic hydrocarbon precursors containing Cl and N, which for this study were chloromethyl naphthalene and quinoline. This method was verified by investigating the structural changes under different synthesis conditions, and the synthesis mechanism induced by aromatics containing Cl was also probed. The result shows that the pyridinic N in quinoline contains a lone pair of electrons, and is an effective active site to induce the polymerization reaction by coupling with aromatic hydrocarbons containing Cl. The reaction between such free radicals causes strong homopolymerization and oligomerization. A higher reaction temperature and longer reaction time significantly increased the degree of polymerization and thus increased the softening point of the pitch. A linear molecular structure was formed by the Cl substitution reaction, which produced a highly spinnable pitch with a softening point of 258.6 °C, and carbon fibers with a tensile strength of 1 163.82 MPa were obtained. This study provides a relatively simple and safe method for the preparation of high-quality spinnable pitch.

Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance carbon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperatures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly improve the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pretreatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a catalyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.

Polyether ether ketone (PEEK) has good mechanical properties. However, its high viscosity when molten limits its use because it is hard to process. PEEK nanocomposites containing both carbon nanotubes (CNTs) and polyether imide (PEI) were prepared by a direct wet powder blending method using a vertical injection molding machine. The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50% while producing an increase in the toughness of the nanocomposites, whose strain to failure increased by 129%, and fracture energy increased by 97%. The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance. This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.

Graphitized carbon foams (GFms) were prepared using mesophase pitch (MP) as a raw material by foaming (450 °C), pre-oxidation (320 °C), carbonization (1 000 °C) and graphitization (2 800 °C). The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared, and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage. Semi-quantitative spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm derived from it. Combined with microscopic observations, the change from precursor to GFm was analyzed. The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch, which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties. Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores, giving the best compression resistance (2.47 MPa), the highest thermal conductivity (64.47 W/(m·K)) and the lowest electrical resistance (13.02 μΩ·m). Characterization combining semi-quantitative spectroscopic analysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.

Petroleum coke (PC) is a valuable precursor for sodium-ion battery (SIB) anodes due to its high carbon content and low cost. The regulation of the microcrystalline state and pore structure of the easily-graphitized PC-based carbon is crucial for creating abundant Na⁺ storage sites. Here we used a precursor transformation strategy to increase the carbon interlayer spacing and generate abundant closed pores in PC-based carbon, significantly increasing its Na⁺ storage capacity in the plateau region. This was achieved by introducing a large number of oxygen functional groups through mixed acid treatment and then using high-temperature carbonization to decompose the oxygen functional groups and rearrange the carbon microcrystallites, resulting in a transition from open to closed pores. The optimized samples provide a large reversible capacity of 356.0 mAh g⁻¹ at 0.02 A g⁻¹, of which approximately 93% is below 1.0 V. Galvanostatic intermittent titration (GITT) and in-situ X-ray diffraction (XRD) analysis indicate that the sodium storage capacity in the low voltage plateau region involves a joint contribution of interlayer insertion and closed pore filling processes. This study presents a comprehensive method for the development of high-performance carbon anodes using low-cost and highly aromatic precursors.