Lihua Zou

Polyethylene terephthalate (PET) fibers have been widely used in various industrial fields due to their excellent chemical and physical performance. However, there is still a crucial problem of the massive precipitation of oligomers from the interior to the surface of product, which results in decreased production efficiency and harm to human health. A quantitative characterization method for surface oligomers of PET fibers based on Soxhlet extraction was developed, with lower-temperature extraction, high accuracy, excellent extraction effect and wider operability. The extraction temperature (Toe) decreased by 30°C compared to the conventional extractant of tetrachloroethylene (Te-Ex), benefiting from the trichloroethylene (Tr-Ex) extractant. The pre-wash process with trichloroethylene could ideally remove oil impurities of about 0.09% but retain the surface oligomers on the fibers, endowing the method of with promising accuracy. PET staple fibers with various contents of surface oligomers were extracted with Tr-Ex, and the achieved contents (i.e. 0.320%/0.527%/0.876%) were similar to those with Te-Ex (i.e. 0.307%/0.516%/0.828%), and the contents with Tr-Ex were all slightly higher than those with Te-Ex, indicating that the extraction efficiency of Tr-Ex improved by ∼4.10% compared with that of Te-Ex. It was confirmed that Tr-Ex method has excellent accuracy compared with as the Te-Ex method and better extraction effect than the Te-Ex method; maybe possibly dipole–dipole interaction between trichloroethylene and oligomer molecules was responsible for the better effect. This quantitative characterization method has potential application in industrial online measurement of surface oligomers on PET fibers, films and related materials.

With the development of aerospace and modern industry, the demand for carbon fiber reinforced composites (CFRP) with both excellent electromagnetic shielding properties and high mechanical properties became necessary. Herein, a novel modified CFRP with multiscale and hierarchical “rigid‐flexible” nanostructured interphase was constructed by feasible and simple methods. Initially, “flexible” deposited polydopamine (PDA) and “rigid” 2D MXene nanosheets were subsequently introduced on the carbon fiber (CF) surface by dip‐coating method, and then 1D nickel (Ni) chains were further constructed on the surface of modified CF by spray coating approach. At last, the modified CF and epoxy were prepared into related composites (CF‐PDA‐MXene‐Ni/EP) by vacuum‐assisted resin transfer molding (VARTM) method. Results showed that the tensile properties of the modified composite were highly improved compared to those of original CF/EP. The strength and modulus could reach 542.80 MPa and 7.30 GPa, which were respectively 23.59% and 23.94% higher than those of CF/EP. Meanwhile, the tensile failure modes of the composite changed from neat fracture to shear breaking of fiber and yarns. Moreover, the EMI SE of modified composite could reach 68.88 dB, which was improved by 7.07% compared to that of original composite. The innovative design of these kinds of composites offered broad prospects for the next generation of excellent EMI shielding and high mechanical materials.Highlights: Polydopamine, 2D MXene, and 1D Ni chains were introduced on carbon fabrics. CF‐PDA‐MXene‐Ni/EP composite was fabricated by the VARTM method. Electromagnetic shielding, as well as tensile behaviors of the composite, were analyzed.

Carbon nanofibers (CNFs) exhibit inherent dielectric properties that enhance electromagnetic (EM) wave absorption, yet challenges exist in expanding their effective absorption bandwidth (EAB) and improving flexibility. Many studies fail to adequately consider how structural factors influence performance when combining CNFs with magnetic materials. To address these issues, a 1D carbon nanocomposite is developed by embedding magnetic oxide nanoparticles within CNFs using a simple electrospinning technique. This approach improves membrane flexibility by disrupting rigid alignment and introducing dynamic magnetic interactions, while also creating defect‐rich interfaces that increase the amorphous content (61%) of the CNFsF composite, leading to improved EM wave absorption. The unique macro/mesoporous morphology provides internal interfaces and heterogeneous boundaries that effectively trap and dissipate EM waves. As a result, the flexible CNF composites demonstrate significant EM wave absorption performance, achieving a minimum reflection loss (RL_min) of −39.8 dB at 4.64 GHz and an abroad EAB of up to 7 GHz at only 2.5 mm thickness. Computer simulation technology (CST) simulations indicate a maximum radar cross‐section reduction of 21.1 dB m², highlighting the material's radar stealth capability. This research advances the development of high‐performance materials and offers new strategies for enhancing absorption properties through composite engineering.

Chelated titanate (CT) modified single‐layer graphene (CTMSG), exhibiting much better static and dynamic stability due to the synergy of physical and chemical bonds, was mixed with butadiene‐vinylpyridine latex (BL) to prepare composite (CTMSG‐BL) film to enhance its thermal conductivity. Furthermore, CTMSG‐BL was complexed with polyethylene terephthalate (PET) fabric to promote the thermal conductivity of the composite (CTMSG‐BL/PET). Compared with the samples without CTMSG, the thermal conductivity of CTMSG‐BL (CTMSG content: 0.2 wt%) and CTMSG‐BL/PET increased from 3.52 to 4.35 W/(m·K) and from 1.91 to 2.56 W/(m·K), improved by 19.1% and 34.0%. This benefits from the excellent orientation alignment of single‐layer graphene (SG) in BL film and the highly efficient construction of the thermal conductivity pathway. The CTMSG‐BL emulsion is suitable for preparing heat‐resistant thermal conductive film with a thickness of micro‐nano meter (~0.6 μm) by impregnation process because of the low viscosity of the CTMSG‐BL emulsion (3.61 mPa·s) and the good heat resistance of the pyridine groups of BL with average pyrolysis temperature about 444 °C. The CTMSG‐BL film and CTMSG‐BL/PET composites have excellent heat conduction and dissipation properties, exhibiting broad application prospects in thermal interface materials, aerospace, and transport.Highlights: The static and dynamic stability of the CTMSG was significantly improved. Low viscosity CTMSG‐BL is suitable for preparing thermally conductive films. With the addition of CTMSG, the thermal conductivity of BL improved by 19.0%. With addition of CTMSG, the thermal conductivity of BL/PET improved by 34%.