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[Display omitted] • Mechanical and tribological properties of PAA/EP composites were enhanced by HSiNH 2. • Compatibility of PAA and EP was improved by using HSiNH 2 as "bridging structure". • PAA was prepared by ball milling method based on the friction chemistry principle. Despite the great application potential of epoxy resin (EP) modified with polyamic acid (PAA), the large amount of high-boiling-point non-protonic polar solvents used to promote their compatibility cannot be completely eliminated, which affects the fabrication and application of epoxy composites in practical engineering. Herein, PAA was prepared by solvent-free ball milling method, and then the primary amine hyperbranched polysiloxane (HSiNH 2) was prepared by "one-pot" method as the "bridging structure" to improve the compatibility between PAA and EP. Compared to neat EP, the flexural, impact and tensile shear strength of the epoxy composite are increased by 22.2 %, 30.0 % and 23.2 %, while the average friction coefficient and volume wear rate are reduced by 26.5% and 20.6% under the contents of PAA and HSiNH 2 are 1.50 wt% and 2.0 wt%, respectively. Moreover, the material exhibits excellent thermal properties. By comprehensively analyzing the structure and properties of the epoxy composite, it is mainly ascribed to the fact that HSiNH 2 with a large number of reactive groups acted as a "bridging structure" to enhance the compatibility of PAA and EP, which results in the epoxy composite having excellent mechanical, tribological and thermal properties. This research also lays the theoretical foundation for the development of high-performance epoxy composites in aerospace. [ABSTRACT FROM AUTHOR]

[Display omitted] • HBPSi-V and rGO-MoS 2 nanomaterials were fabricated respectively. • HBPSi-V could affect the distribution and nanostructured rGO-MoS 2 interface in matrix. • Superior tough, wear durable and self-lubricating EP composite was constructed. • The synergism of soft and hard nanomaterials was discussed and highlighted. Despite many efforts are being undertaken to design high tribo-performance epoxy nanocomposite, it still remains a great challenge to comprehensively address the interface issue and poor mechanical strengths for real engineering requirements. This work reports a facile yet efficient strategy (synergism of soft and hard materials) to coordinate the interface-property relationship. Herein, we composited graphene with molybdenum disulfide to fabricate rGO-MoS 2 interlayered nanostructure as hard solid lubricant, as the hyperbranched polysiloxane with unique flexible Si O C backbone was synthesized via facile polymerization as soft component within epoxy network. These two nanomaterials can be well used to construct EP composite for easy processing, and their merits regarding lubricity and toughening are well exerted, especially the interface could be improved without surface treatment. The optimized material with superior impact strength (23.5 ∼ 37.4 kJ·m−2), low friction coefficient (0.42 ∼ 0.16) and volume wear rate (70.6 % reduction) was obtained with respect to previous counterparts. Interestingly, TEM of ultra-thin resin slice found that hyperbranched polysiloxane could affect the distribution and nanostructured interface of graphene/MoS 2 , encouraging a facile and low-cost approach towards surface engineering of high-performance polymer composite. Besides, the tribo-mechanism and nano-reinforced mechanism were investigated and discussed in detail. In light of the compelling effects, this work paves an effective way toward the designs of high-performance polymer tribo-materials for real engineering uses. [ABSTRACT FROM AUTHOR]

The design of high transparent epoxy resins (EPs) with excellent flame retardancy and mechanical strength is still intractable, while the current use of phosphorus-based flame retardant usually destroys the transparency and color of EPs. This work reports a phosphorus-free hyperbranched polyborate (HBPB) as a multifunctional flame retardant additive for EPs. The HBPB was synthesized via a facile, one-pot, solvent- and catalyst-free polycondensation with branched aliphatic backbone and borate group, which features good compatibility within resin matrix and does not affect its curing processability. Compared to neat EP, the as-constructed EP composite with 9% addition of HBPB displays the high fire resistance (30.2% LOI value and UL-94 V0 rating), and the fire hazards such as smoke, heat and toxic gases release are significantly reduced without introducing phosphorus group. Surprisingly, the EP material can well maintain its high transparency and color with ultra-high toughness (21.38–40.50 kJ m−2) and flexural strength (137.03–197.08 MPa) achieved, especially the glass-transition temperature can be improved from 150 °C to 170 °C, making it superior to previously described counterparts. Highlighting the compelling results, this work provides a promising candidate on seeking the halogen-free solutions to alleviate the high price of phosphorus-based FRs, and paves a useful strategy toward designing high transparent, high-performance polymeric materials. [Display omitted] • A novel phosphorus-free hyperbranched polyborate FR was proposed to EPs. • HBPB shows good compatibility and do not affect the curing processability of EP. • The EP composite with superior toughness, fire-retardancy and high Tg was obtained. • EP material can well maintain its transparency with improved overall performance. • A full-scale study was conducted to clear the mechanism of this novel boron-FR. [ABSTRACT FROM AUTHOR]

Plastic combustion has adverse impacts on air quality and human health. In this work, a novel non-aromatic Si, P, N-containing hyperbranched flame retardant (HPNSi) was synthesized and proposed to epoxy resin. The modified epoxy exhibits not only reduced fire hazards and less smoke production in favor of eco-friendly, but also remarkable mechanical properties and lower curing temperature for facile processability. With 6 wt% incorporation, the peak heat release and total smoke production were reduced by 29.6% and 20.7%, respectively, and the time to ignition (TTI) increased as well as the fire growth rate (FIGRA) dropped off, which is of vital significance for saving lives in a fire. Meanwhile, the impact strength and flexural strength greatly enhanced by 72.9% and 22.0%, while its curing temperature was lower than that of controlled EP system. Interestingly, we also found that the solid carbon particles on the char surface apparently reduced from SEM image. The blending of its unique non-aromatic hyperbranched structure containing Si, P, N with epoxy architecture was responsible for the desirable integrated enhancement. The broad possibilities in the field of flame-retardant plastic with reduced fire hazards and excellent integrated performance enable the novel hyperbranched flame retardant a bright future for application. [Display omitted] • Non-aromatic Si, P, N-hyperbranched FR was synthesized by facile polycondensation. • Significantly enhanced flame retardancy and low smoke release were achieved. • The HPNSi/EP exhibits outstanding mechanical properties and rapid curing rate. • Phosphorus group introduce to hyperbranched architecture led to great enhancement. • SEM show that HPNSi may inhibit carbon particle release on the char surface. [ABSTRACT FROM AUTHOR]