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Novel fluorine-containing polyimides were synthesized through copolymerization by using 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) and 4,4′-(4,4′-isopropydenediphenox-y) bis-(phthalic anhydride) (BPADA) as dianhydrides and 4,4′-oxydianiline (ODA) and 2,2 - Bis [4-(4-aminophenoxy)phenyl]-hexafluoropropanane (HFBAPP) as diamines. Noncoplanar structure, flexible ether bond, and trifluoromethyl give the polyimide good thermoplastic, solubility, and heat resistance. The glass transition temperatures of polyimide films are 232.5°C∼262.2°C, the 5% weight loss temperatures are 521.5°C∼531.0°C, and the residual mass is more than 50% as heating to 800°C. With the increase of HFBAPP content in diamine, the dielectric constant of the material decreases from 3.21 to 2.78, and the dielectric loss decreases from 0.00962 to 0.00687 at 1 MHz, which greatly improves the dielectric properties of the material.

Polypropylene (PP) and polyethylene (PE) play central roles in our daily life. However, their immiscibility presents a major hurdle in both industry and academia when recycling them into alloys with favorable mechanical properties. Moreover, typical compatibilizer-enabled approaches are limited due to increased environmental concerns. Herein, inspired by a traditional Chinese technique, we report a facile, industry-scale methodology that produces a PP/PE binary blend with a highly ordered honeycomb nanostructure without any additives. Due to its nanostructure, the blend exhibits enhanced tensile properties in comparison with the parent components or with a sample prepared using an internal mixer. This approach has potential for applications not only in immiscible polymer blending, but also in non-sorting, compatibilizer-free waste plastics recycling. Through this technique, we expect that an environmentally friendly and sustainable plastic wastes recycling avenue can be found, and great economic benefits can be gained.

Halloysite nanotubes (HNTs) have been considered as a promising flame retardant fillers for polymers. In this work, the polyhedral oligomericsilsesquioxane (POSS) containing amino group was covalently grafted on the surface of HNTs with 3-(2,3-epoxypropoxy)propytrimethoxysilane as a chemical bridge. The POSS modified HNTs (HNTs-POSS) dispersed uniformly in the thermoplastic polyurethane (TPU) matrix and endowed TPU nanocomposites with enhanced tensile properties and fire safety. Cone calorimeter tests revealed that the introduction of 2 wt% HNTs-POSS to TPU matrix remarkably reduced the peak of heat release rate (PHRR) and total heat release (THR) by 60.0% and 18.3%, respectively. In addition, the peak CO production rate and total smoke release (TSR) could be significantly suppressed by the addition of HNTs-POSS. The well dispersed HNTs in combination with the ceramified silicon network from the thermal decomposition of POSS contributed to the formation of a continuous and compact char layer, exhibiting a tortuous effect by inhibiting heat diffusion and evaporation of volatile gaseous. In addition, the released crystal water from HNTs could dilute the combustible volatiles and then decline the combustion intensity. The tensile tests demonstrated that introduction of 2 wt% HNTs-POSS would enhance the maximum stress of TPU nanocomposite with a slight decrease of elongation at break. The combination of HNTs and POSS through the construction of effective interfacial interactions provides a feasible way to effectively enhance the fire safety of TPU nanocomposites without scarifying ductility.

There is a great demand for low dielectric materials as insulating interlayers in large-scale integrated circuit development. However, it is still a huge challenge to reduce the dielectric permittivity of polymers while maintaining excellent thermal stability and mechanical properties. In this work, the fluorinated polyimides (PIs) in combination with a micro-branched crosslinking structure were prepared successfully by introducing different amounts of 1,3,5-tris(4-aminophenyl) benzene (TAPB) to obtain ultra-low dielectric permittivity. The results revealed that PI film containing 2 mmol TAPB had the lowest dielectric permittivity (2.47) and dielectric loss (0.008) at 1 MHz due to the fluorine atoms and the micro-branched crosslink structure, which not only decreased the molecular polarizability but also increased the free fractional volume. In addition, PI film containing 2 mmol TAPB had the highest tensile strength of 106.02 MPa with an elongation at a break of 15.1% because the presence of TAPB effectively promoted the connection between PI molecular chains, resulting in the inhibition of the molecular mobility. The incorporation of TAPB also enhanced the thermal stability and ultraviolet light-shielding performance of PI films. This method paves the way for the development of PIs with ultra-low dielectric permittivity for the electronic industry.

Biodegradable polylactide (PLA) has been widely utilized in people’s daily lives. In order to improve the fire safety of PLA, ammonium polyphosphate (APP) was self-assembled onto the surface of serpentine Ni3Si2O5(OH)4 through the electrostatic method, followed by mixing with PLA by melt compounding. The APP-modified serpentine (serpentine@APP) dispersed uniformly in the PLA matrix. Compared with pure PLA, the PLA composite with 2 wt% serpentine@APP reduced the peak heat release rate (pHRR) and total heat release (THR) by 43.9% and 16.3%, respectively. The combination of APP and serpentine exhibited suitable synergistic flame-retardant effects on the fire safety enhancement of PLA. In addition, the dynamical rheological tests revealed that the presence of APP and serpentine could reduce the viscosity of PLA composites. The plasticizing effects of APP and serpentine benefited the processing of PLA. The mechanical properties of PLA/serpentine@APP maintained suitable performance as pure PLA. This study provided a feasible way to enhance the fire safety of PLA without sacrificing its mechanical properties.

Thermoplastic polyurethane (TPU) is widely used in daily life due to its characteristics of light weight, high impact strength, and compression resistance. However, TPU products are extremely flammable and will generate toxic fumes under fire attack, threatening human life and safety. In this article, a nanohybrid flame retardant was designed for the fire safety of TPU. Herein, Co3O4 was anchored on the surface of exfoliated ultra-thin boron nitride nanosheets (BNNO@Co3O4) via coprecipitation and subsequent calcination. Then, a polyphosphazene (PPZ) layer was coated onto BNNO@Co3O4 by high temperature polymerization to generate a nanohybrid flame retardant named BNNO@Co3O4@PPZ. The cone calorimeter results exhibited that the heat release and smoke production during TPU combustion were remarkably restrained after the incorporation of the nanohybrid flame retardant. Compared with pure TPU, the peak heat release rate (PHRR) decreased by 44.1%, the peak smoke production rate (PSPR) decreased by 51.2%, and the peak CO production rate (PCOPR) decreased by 72.5%. Based on the analysis of carbon residues after combustion, the significant improvement in fire resistance of TPU by BNNO@Co3O4@PPZ was attributed to the combination of quenching effect, catalytic carbonization effect, and barrier effect. In addition, the intrinsic mechanical properties of TPU were well maintained due to the existence of the PPZ organic layer.

Thermoplastic polyurethane (TPU) is widely used in daily life due to its characteristics of light weight, high impact strength, and compression resistance. However, TPU products are extremely flammable and will generate toxic fumes under fire attack, threatening human life and safety. In this article, a nanohybrid flame retardant was designed for the fire safety of TPU. Herein, Co

The incorporation of high-dielectric permittivity ceramic or conductive fillers into the polymer is an effective method to obtain flexible high-performance dielectric materials, but it is still a huge challenge to achieve a balance between dielectric and mechanical properties. In this paper, we report a polyvinylidene fluoride (PVDF) nanocomposite based on a novel crab leg-like filler, in which Ag nanoparticles (AgNPs) were decorated on the surface of polydopamine (PDA)-coated silicon carbide (SiC) nanowhiskers (NWs). Compared with the nanocomposites with as-received SiC, this PVDF/SiC@PDA@Ag nanocomposites exhibited significantly suppressed dielectric loss (0.03 at 1 kHz) and leakage current. The Argant plot ( $${\varepsilon }^{^{\prime}}$$ - $${\varepsilon }^{\prime\prime}$$ curve) and electric modulus analysis demonstrated that the inhibition of the organic layer of PDA to interface polarization and the coulomb-blockade effect of AgNPs hindered carrier transport, which resulted in the largely suppressed dielectric loss. Furthermore, while the dielectric properties were improved, the PVDF/SiC@PDA@Ag nanocomposites also exhibited excellent mechanical and thermal conductivity. Ultimately, the nanocomposites prepared via this method are promising for applications in microelectronic devices.

Composite bipolar plates (BPs) are preferred to graphite BPs and metal BPs, in proton exchange membrane fuel cells (PEMFC), due to their pronounced advantages. However, facile and high-efficiency fabrication of high performance composite BPs, remains a challenge. In this study, high performance polyvinylidene fluoride (PVDF)/graphite/multi-walled carbon nanotubes (MWCNTs) composite BPs with segregated conductive network are prepared by structural design and compression molding. Due to the “brick-mud” structure formed in composite BPs by structural manipulation, its conductivity of low filler content is greatly improved. In addition, segregated synergistic conductive networks are observed in composite BPs after adding MWCNTs. The composite BP (5 wt% MWCNTs and 35 wt% graphite) exhibited electrical conductivity of 161.57 S/cm and area specific resistances of 7.5 mΩ cm2. Moreover, the composite BPs have good flexural strength, excellent hydrophobicity and corrosion resistance. In summary, our work provides a simple and feasible strategy for manufacturing high performance composite BPs with low fillers.

In this paper, the synthesized thermoplastic polyimide (TPI) precursor is coated on both surfaces of the surface-treated polyimide (PI) base film, and the TPI/PI/TPI multilayer films is obtained by thermal imidization. The mechanical properties, heat resistance, water absorption of the multilayer film and the interface between the TPI and the PI base film were investigated in detail. Then, multilayer film-2 (MF-2) with excellent comprehensive performance and the two copper foils were pressed together to prepare a double-sided flexible copper clad laminate (FCCL) by thermal lamination method, and the properties of FCCL were studied in detail. The results show that the FCCL has a high peel strength of 1.22 N/mm, passed a solder bath test of 288°C, and the surface condition was good under hot-pressing temperature of 360°C, hot-pressing pressure of 15 MPa and hot-pressing time of 60 s. In addition, the SEM and EDS spectra of the stripped copper foil confirmed that the TPI layer was immersed into the interstitial space of the Cu nodules, forming a strong physical bite with the copper foil. The current work provides a promising solution for the design and fabrication of multilayer printed circuit boards with excellent performance.

A facile photo-irradiation method is developed to tune active sites over β-Ni(OH)2 nanosheets. Photo-irradiated β-Ni(OH)2 nanosheets possess disordered surface atoms and preferred growth of highly active crystal facets, which exhibit enhanced performance for the electrocatalytic oxygen evolution reaction.

A series of novel quaternary copolymerized thermoplastic polyimides were successfully prepared with asymmetric diahydride: 3,4′-oxydiphthalic anhydride (a-ODPA) and symmetric anhydride: 4,4′-oxydiphthalicanhydride (s-ODPA), 9,9′-bis(4-aminophenyl)fluorene (BAFL) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) as diamine. The synergistic effect of non-coplanar structure, fluorenyl cardo groups, methyl groups and flexible groups on the solubility, heat resistance and thermoplasticity of polyimide was discussed. The experimental results showed that the addition of BAFL greatly improved the heat resistance of polyimide. The glass transition temperature (Tg) of PI-A~PI-E with different ratios were 235.3–305.5 °C. Compared with control group PI-F, PI-A~PI-E were completely soluble within 3 h in DMF, DMAc, NMP, showing that they had excellent solubility, and what’s more, under the synergistic effect, the thermoplasticity of PI-A~PI-E was also greatly improved.

A facile photo-irradiation method is developed to tune active sites over β-Ni(OH)

The demand for biodegradable and renewable UV-shielding materials is ever increasing due to the rising concern for the environment. In this paper, biobased lignin was functionalized by polyhedral oligomeric silsesquioxane (POSS) with an epoxy substituent. Then the POSS decorated lignin (lignin-POSS) was mixed with polylactide (PLA) to act as UV-shielding filler by melt compounding. The SEM observation revealed that the presence of POSS contributed to improving the homogeneous dispersion of lignin-POSS in the PLA matrix with good compatibility when the content of lignin-POSS was lower than 5 wt%. The synergistic effects of lignin and POSS endowed PLA composite films with a good balance of UV-shielding ability and transparency in the visible light region. With the addition of 5 wt% lignin-POSS, the PLA composite film absorbed almost all UV irradiation across the entire UV spectrum. In addition, the presence of lignin-POSS could serve as a nucleating agent to increase the degree of crystallinity of PLA. The dynamical rheological tests revealed that the lignin-POSSS reduced the complex viscosity and storage modulus of PLA composites, improving the flowability of PLA composites. This work presents a viable pathway to prepare biodegradable and renewable UV-shielding materials for potential packaging applications.

It is highly desirable to develop biodegradable UV-shielding materials from the renewable resources as the ever-increasing demand for the sustainable environment. In this work, TiO2 decorated lignin particles (TiO2@lignin) were synthesized successfully by hydrothermal method in aqueous solution to improve the UV shielding performance of lignin particles. The poly(propylene carbonate) (PPC) composite films (thickness of ~23 μm) with different contents of TiO2@lignin were prepared via a blade-casting method. Morphological analysis showed that the TiO2@lignin dispersed uniformly in the PPC matrix with a good miscibility. UV–vis transmission spectra results revealed that the PPC composite film containing 5 wt% TiO2@lignin could absorb about 90% of UV light in the full UV band (200–400 nm), indicating the TiO2@lignin had a good UV-shielding property. Moreover, the presence of TiO2@lignin could significantly improve the thermal stability of the PPC/TiO2@lignin composite films. The DMA results showed that the introduction of TiO2@lignin could enhance the storage modulus and glass transition temperature simultaneously.

In this work, nitrile rubber (NBR) with high strength and recycling ability was designed based on the interaction between metal ions and ligands. Herein, we first epoxidized the nitrile rubber late...

A series of quaternary copolymerized thermoplastic polyimides (PI) films with good thermal resistance has been synthesized via two-step method from bicomponent isomeric dianhydrides, 2,3′,3,4′-biphenyltetracarboxylic dianhydride (α-BPDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA), and bicomponent flexible diamines, 4,4′-oxydianiline (ODA) and 1,3-bis(4′-aminophenoxy)benzene (TPE-R). By adjusting the molar ratio of dianhydrides to diamines, its effects on the thermal stability, thermoplasticity and solubility of PI films were investigated in detail. The results showed that these quaternary copolymerized PI films were in possession of both thermoplasticity and excellent thermal stability. It is derived from the synergetic effect of isomeric dianhydrides and flexible diamines. It has also been found that there is one critical molar ratio between dianhydrides and diamines, that is, α-BPDA:s-BPDA:ODA:TPE-R = 50:50:50:50, at which the overall performance is optimal.

To alleviate traffic congestion and support the development of real-time traffic and public transport, this paper conducts research on adopting support vector regression (SVR) and long short term memory (LSTM) to predict traffic flow of the lane, and then compares the results with that using the quadratic exponential smoothing. The consequence shows that SVR and LSTM have better prediction accuracy, about 1%–3% in terms of MAPE, than quadratic exponential smoothing, and SVR is slightly better than LSTM. Furthermore, in order to improve the predictive accuracy of model, we compare the performance of grid search, whale optimization algorithm (WOA) and genetic algorithm (GA) respectively in the respect of optimizing models’ parameters. The optimization effect of WOA-SVR and WOA-LSTM is better than the other two models respectively, about 0.9% and 2.52% better than GA-SVR and GA-LSTM while 0.29% and 2.32% better than GridSearch-SVR and GridSearch-LSTM considering MAPE.

Porous ultra-high-molecular-weight polyethylene (UHMWPE) self-lubricating materials were designed and fabricated by a rotary sintering method, and the microstructure and properties were evaluated. Results showed that the rotary molding could not only significantly improve the molding efficiency but also formed uniform internal microstructures with high porosity, excellent mechanical properties, and low friction coefficient. Under oil lubricating conditions, the friction curve of samples quickly reached a steady state, the friction coefficient was reduced by 50%, and the repeat utilization was up to 99%. The following optimum sintering conditions were shown: Sintering temperature of 180 &deg, C or 190 &deg, C, sintering time determined as 10 min, and loading capacity of between 3.6 g and 3.8 g. Therefore, it is expected that this work will open a convenient and compatible strategy for fabricating porous materials with good self-lubricating performance.

Lignin can be employed as a sustainable functional additive and reinforcement filler for polymers. In this work, melamine phosphate modified lignin (MAP-lignin) was synthesized as a bio-based halogen-free flame-retardant agent. The synergetic effects between MAP-lignin and rice husk ash (RHA) on the thermal stability, dynamic mechanical performance and flame-retardant properties of the poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) biocomposites were investigated. The results revealed that MAP-lignin and RHA could significantly increase the char residue and MAP-lignin had a good miscibility with P34HB. The incorporation of MAP-lignin and RHA as stiff fillers could enhance the storage modulus of the P34HB matrix. Moreover, the tensile strength and elongation at break of the P34HB/RHA composite could be improved due to the MAP-lignin could serve as a compatibilizer to improve the interaction between RHA and P34HB. Cone calorimetry data demonstrated that the addition of 30 wt% MAP-lignin and 5 wt% RHA reduced the peak heat release rate (PHRR) and total heat release (THR) of P34HB noticeably by 42.8 and 24.3%, respectively. In addition, the CO2 production rate and CO concentration could be significantly suppressed by the addition of MAP-lignin. The enhanced flame retardancy of P34HB composite should be ascribed to the barrier effect of the increased char residue with compact and intact structure, as well as the released gases from the decomposition of melamine.

Ultra-high molecular weight polyethylene (UHMWPE)/carbon nanotubes (CNT) porous skeleton was prepared by microwave sintering, then paraffin wax (PW) was absorbed into UHMWPE/CNT porous skeleton by vacuum, obtaining composite phase change materials (CPCM). Differential scanning calorimetry (DSC) results showed that with CNT content of 1.5%, the PW adsorption of CPCM reached 59.91% and latent heat of the CPCM hardly changed after 20 melting/freezing cycles. Furthermore, thermal conductivity of porous matrix and CPCM from 0.1858 and 0.3012 W m − 1 K − 1 to 0.3272 and 0.4225 W m − 1 K − 1 with the CNT content increased (from 0% to 2%), respectively. In addition, the CPCM had a great shape stability. When the temperature reached 70 °C, PW in CPCM hardly leaked. In the photothermal conversion, CPCM realized the function of energy storage and release. Therefore, the CPCM prepared by a facile and environmentally friendly strategy with high energy storage efficiency, outstanding thermal repeatability, excellent thermal stability and high thermal conductivity had a broad prospect in the application of energy storage.