Xiaopeng Yue

A dialdehyde nanocellulose (DAC)/sodium alginate (SA) composite aerogel was engineered around an orthogonal dual‐crosslinking architecture: a primary Schiff‐base network between DAC and polyethyleneimine‐modified ammonium polyphosphate (PAPP), and a secondary Fe ³⁺ coordination network with the carboxyl and phytate groups. The introduction of phytic acid enhanced the flame‐retardant system through N/P synergy. Tannic acid‐functionalized graphene oxide (TA/GO) was filled into the Schiff base network, effectively improving the sound absorption and flame‐retardant properties of the material. The resulting specimen excels in mechanical strength, achieving a compressive modulus of 36.99 kPa and a specific modulus of 3977.4 kPa·g ⁻¹ ·cm ³ at 60% compression, surpassing DAC/SA by 3.9 and 3 times, respectively. The prepared composite aerogel also achieved prominent flame‐retardant effects. It yielded a LOI of 37.4% and fulfilled the V‐0 rating standard in UL‐94 vertical flame tests, accompanied by 79.7% and 69.8% reduction in pHRR and THR. Further investigation revealed that the prepared composite aerogel demonstrated superior acoustic properties, with an NRC of 0.58 and an average sound absorption coefficient of 0.806, fully reaching the standard for high‐performance sound‐absorbing materials. These remarkable features enable the composite aerogel to be a competitive material for architectural fireproofing and noise reduction applications.

To synergistically enhance the dielectric and magnetic losses of carbon fiber (CF) paper‐based composites, the surface of CFs was modified with nano‐Fe ₃ O ₄ , nano‐FeNi ₃ , and flake nano‐FeNi ₃ (LFeNi ₃ ) magnetic nano‐alloys combined with polyaniline (PANI). A series of modified CF/plant fiber electromagnetic interference (EMI) shielding papers were fabricated via wet papermaking and hot pressing. The results showed that the magnetic nanoparticles were uniformly deposited on the CF surface along with PANI. Among the magnetic materials, LFeNi ₃ exhibited the highest saturation magnetization (87.5 emu/g) and coercivity (60.5 Oe), demonstrating its superior ferromagnetic properties. The tensile strength of the P‐LFeNi ₃ @PACF reached 3.1 kN/m, which was 47.6% higher than that of the unmodified CF paper. In X‐band, the total EMI shielding effectiveness (SE _T ) of P‐LFeNi ₃ @PACF reached 37.90 dB, representing increases of 46.7% and 22.8% compared with unmodified CF paper and pure PANI‐modified paper, respectively. It is found that the reflectivity ( R ) values are significantly higher than the absorptivity ( A ) values, indicating that the experimentally measured shielding behavior is actually reflection‐dominated. P‐LFeNi ₃ @PACF exhibited the strongest dielectric and magnetic loss capabilities. Via morphological control of magnetic nanoparticles and synergistic modification with PANI, the EMI shielding performance of CF paper‐based composite can be significantly enhanced. This strategy offers an economical and practical approach for preparing high‐performance multifunctional EMI shielding materials.

A copolymer of alkali lignin and polyacrylamide was fabricated by graft copolymerization, and further chelated with Fe³⁺. The obtained lignin chelate with star structure was used as synergistic agent and catalyst with the incorporation of intumescent flame retardants (IFRs) to prepare flame‐retarded poly (butylene succinate) (PBS) composites. The replacement of IFR by lignin chelate favors the enhancement of mechanical performance, resulting in the synchronous improvement of tensile and flexural properties. Compared with the specimen used 25 wt% IFRs (75P/25I), the tensile strength, flexural strength, and modulus of specimen prepared by 23 wt% IFRs and 2 wt% lignin chelate (75P/23I/2LC) exhibited significant increased. A synergistic effect between IFR and lignin chelate occurred when they were combined with an appropriate ratio. When IFR and lignin chelate loadings were 24 and 1 wt%, respectively (75P/24I/1 LC), the limited oxygen index (LOI) value of 36.2% and UL‐94 V0 rate of composite could be achieved. Compared with 75P/25I, the char residue mass of 75P/24I/1 LC increased by 35.7%. Moreover, SEM images indicated that a more compact, smooth, and continuous char layer of 75P/24I/1 LC could be formed during combustion. The peak heat release rate (pHRR) and total heat release (THR) of 75P/24I/1 LC decreased by 58.9% and 9.9% compared with PBS, also decreased by 10.3% and 4.8% compared with 75P/25I, respectively. TGIR and FTIR analysis also indicated that lignin chelate exhibited an excellent synergistic effect with IFRs, and gave PBS a good flame retardancy by making contribution to char‐formation and gas‐phase flame retardancy. This study provides an alternative way for the application of natural polymers such as lignin in flame retardant materials.

Lignin/montmorillonite (LM) nanocomposites were fabricated via intercalating lignin colloid particles into the layer space of montmorillonite (MMT), and used as a synergistic agent to prepare flame‐retardant poly(butylene succinate) (PBS) composites with the incorporation of intumescent flame retardants (IFR). Using lignin colloidal nanoparticles with the particle size ranged from several to about 100 nm formed under alkali condition, the layer spacing of MMT could be exfoliated and expanded to a considerable extent. The obtained LM nanocomposites could disperse with a uniform status in PBS matrix by melt compounding. Thus, strengthened mechanical performance of composites could be achieved via replacing partial loading of IFR by LM. Besides, due to the synergetic effect between IFR and LM, the flame‐retardant properties of composites were enhanced when they were combined with an appropriate ratio. Typically, when IFR and LM loadings were 22 and 3 wt%, respectively, the tensile strength of 75P/22I/3LM increased by 24.73% in comparison with that of composite only prepared by IFR(75P/25I). Simultaneously, 36.5% of limited oxygen index (LOI) value and UL‐94 V0 rate for 75P/22I/3LM could also be achieved. TG‐IR analysis indicated that the addition of lignin increased the amount of inert gas generated. A carbonaceous silicate layer could be formed by MMT and lignin under the catalytic effect of APP, resulting in the increase of char residue after combustion. Cone calorimeter analysis demonstrated that the peak of heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) of 75P/22I/3LM decreased by 57.4%, 28.7% and 33.8% compared with pure PBS, respectively.

Environmental problems caused by polymers and polymers have historically dominated both academic and industrial attention. Sustainable biodegradable wood‐plastic composites (WPCs) as an optimum can solve the environmentally critical problems caused by petroleum‐based polymers. However, they are flammable, prone to fire accidents, and often have a contradiction between mechanical performance and flame‐retardant properties, which limits their range of applications. Here, we reported a flame‐retarded poly(butylene succinate) (PBS) WPC prepared with modified natural fiber‐magnesium hydroxide sulfate whisker (MHSH) hybrids and intumescent flame retardants (IFRs). The mechanical performance, flame‐retardant properties, thermal stability, and actual fire simulation parameters of composites were investigated. Owing to the unique composition characteristics of modified cassava dregs‐MHSH hybrids, the mechanical properties (70P/23I/5C/2M, flexural strength was 39.2 ± 1.960/MPa, impact strength was 7.95 ± 0.3975/ [KJ/m²]), flame retardant properties (70P/23I/5C/2M, the limiting oxygen index value was 39.6%, UL‐94 was V0) and thermal stability of WPC have been improved. Thereby, the balance between mechanical performance and flame retardant properties of biocomposites has been achieved in the practical engineering requirements. Furthermore, cone calorimeter data indicated that modified cassava dregs–MHSH hybrids played a role in improving the fire safety of composites. The total heat release, total smoke produce, toxic gas release, and total oxygen consumed of 70P/23I/5C/2M were lowered compared with those of 70P/25I/5C. Dynamics analysis indicated that the addition of modified cassava dregs–MHSH hybrids increased the activation energy of composites. Based on the experimental and analyses data, especially the morphological characterization of char residue analysis, it illustrated that modified cassava dregs–MHSH hybrids have a reinforcement and flame‐retardant effect. The combusted residue of the incorporated modified cassava dregs–MHSH hybrids could support the three‐dimensional charred layer formed by the combustion products of the IFR and the PBS. Thus, the more stable three‐dimensional charred layer could not only effectively reduce thermal conductivity of composites but also hinder the propagation of heat into the interior substrate, thereby improving the flame‐retardant properties of the WPC. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48490.