Herein, the electromagnetic interference (EMI) shielding and electrothermal properties of MXene‐coated cellulose hybrid papers (MCPs) and fabrics (MCFs) with high flexibility and low density, which are manufactured by a dip‐dry coating approach, are reported. For this purpose, MCPs and MCFs are fabricated by dipping cellulose papers and fabrics repeatedly into an aqueous dispersion of MXene. The electron microscopic and X‐ray diffraction data reveal that MXene sheets are coated uniformly on the surfaces of cellulose fibrils and fibers and that their contents increase with the dip‐dry coating cycle. For MCP10 (5.68 wt% MXene) and MCF10 (11.77 wt% MXene), which are manufactured by ten‐time dip‐dry coating cycles, high electrical conductivity of 1.91 and 0.08 S cm−1 are attained, respectively. In addition, MCP10 and MCF10 possess excellent absolute EMI shielding effectiveness (SSEt) of 2198 and 1100 dB cm2 g−1 at 8 GHz, respectively, which is due to the multiple internal reflection and absorption of incident EM waves by conductive and interconnected MXene‐coated cellulose fibrils and fibers. It is also found that MCP1 (0.9 wt% MXene) and MCF1 (1.9 wt% MXene) at one‐time dip‐dry coating cycle show outstanding electrothermal performance in aspects of high saturated temperatures and energy conversion efficiency at low applied voltages.

No abstract

No abstract

To attain thermoplastic polymer composites with enhanced thermal and mechanical properties as well as long‐term durability, in this study, polyurethane‐coated carbon fiber (CF) and electron beam (EB) irradiation are adopted as an effective reinforcing filler and efficient crosslinking process, respectively. For this purpose, polyamide 6 (PA)‐based composites with different CF contents of 1–10 wt% were fabricated through melt‐compounding and compression molding, and then irradiated with various EB doses of 50–200 kGy. The SEM and FT‐IR data reveal that CFs are well dispersed in the PA matrix with excellent interfacial adhesion via specific intermolecular interactions, which are even enhanced for the composites with crosslinked PA matrices after the EB irradiation. As the result, the thermal stability (initial decomposition temperature and residue at 800°C) and dynamic mechanical properties of PA/CF composites increased noticeably with increasing the CF content and EB irradiation dose. The initial storage modulus of 1.90 GPa for neat PA at 30°C was improved significantly to 2.94 GPa by 10 wt% CF addition and to 4.67 GPa by 200 kGy EB irradiation. In particular, the long‐term mechanical properties of PA/CF composites, which were evaluated using a stepped isothermal method based on the time–temperature superposition principle, were found to be highly enhanced by the synergistic effect of CF filler reinforcement, EB‐induced PA matrix crosslinking, and improved interfacial adhesion.

In this study, a series of thermotropic liquid crystalline polyester (TLCP)-based blends containing 1–30 wt% poly(ethylene-co-glycidyl methacrylate) (PEGMA) were fabricated by masterbatch-assisted melt-compounding. The scanning electron microscopy (SEM) images showed a uniformly dispersed microfibrillar structure for the TLCP component in cryogenically-fractured blends, without any phase-separated domains. The FT-IR spectra showed that the carbonyl stretching bands of TLCP/PEGMA blends shifted to higher wavenumbers, suggesting the presence of specific interactions and/or grafting reactions between carboxyl/hydroxyl groups of TLCP and glycidyl methacrylate groups of PEGMA. Accordingly, the melting and crystallization temperatures of the PEGMA component in the blends were greatly lowered compared to the TLCP component. The thermal decomposition peak temperatures of the PEGMA and TLCP components in the blends were characterized as higher than those of neat PEGMA and neat TLCP, respectively. From the rheological data collected at 300 °C, the shear moduli and complex viscosities for the blend with 30 wt% PEGMA were found to be much higher than those of neat PEGMA, which supports the existence of PEGMA-g-TLCP formed during the melt-compounding. The dynamic mechanical thermal analysis (DMA) analyses demonstrated that the storage moduli of the blends decreased slightly with the PEGMA content up to 3 wt%, increased at the PEGMA content of 5 wt%, and decreased again at PEGMA contents above 7 wt%. The maximum storage moduli for the blend with 5 wt% PEGMA are interpreted to be due to the reinforcing effect of PEGMA-g-TLCP copolymers.