Silicone/graphene oxide co-cross-linked aerogels with wide-temperature mechanical flexibility,super-hydrophobicity and flame resistance for exceptional thermal insulation and oil/water separation

Development of multifunctional and high-performance silicone aerogel is highly required for various promising applications.However,unstable cross-linking structure and poor thermal stability of silicone network as well as complicated processing restrict the practical use significantly.Herein,we report a facile and versatile ambient drying strategy to fabricate lightweight,wide-temperature flexible,super-hydrophobic and flame retardant silicone composite aerogels modified with low-content functionalized graphene oxide(FGO).After optimizing silane molecules,incorporation ofγ-aminopropyltriethoxysilane functionalization is found to promote the dispersion stability of GO during the hydrolysis-polymerization process and thus produce the formation of unique strip-like co-cross-linked network.Consequently,the aerogels containing∼2.0 wt%FGO not only possess good cyclic compressive stability under strain of 70%for 100 cycles and outstanding mechanical reliability in wide temperature range(from liquid nitrogen to 350℃),but also display excellent flame resistance and super-hydrophobicity.Further,the optimized silicone/FGO aerogels display exceptional thermal insulating performance superior to pure aerogel and hydrocarbon polymer foams,and they also show efficient oil absorption and separation capacity for var-ious solvents and oil from water.Clearly,this work provides a new route for the rational design and development of advanced silicone composite aerogels for multifunctional applications.

Study of intumescent flame-resistant fluoroelastomer

The efficiency of different intumescent flame-retardant （IFR） formulations designed to improve the flame resistance of fluoroelastomer （ FKM ） composites was studied. The proportion of ammonium polyphosphate （APP） with charring-foaming agent （CFA） in IFR systems, and the addi- tion of synergists zinc borate （ZB） and ketonealdehyde resin （ KR120 ） were investigated to show their effect on flame resistance of FKM. According to flame resistance tests, when the mass ratio of APP to CFA was 4：1 as well as the loadings of IFR, ZB, KR120 were 83 parts per hundred resin （phr）, 13phr, 25phr, respectively, the FKM-KR120/IFR-ZB composites had good synergetic flame resistant effect. TGA data showed that IFR and synergists could obviously lower the maximum weight loss rate of FKM composites and effectively increase the char residue at high temperature. The morphological structures of the composites observed by scanning electron microscopy （SEM） demonstrated that the addition of ZB and KR120 could clearly reduce the cracks in char residue and make the char layer structure more integrated and compact.

Experimental Study of Electrodes Parameters Effects on Small Diffusion Combustion Flame

To study the configuration and conductivity effects on micro-scale methane-air flames by electric field and iron wind,different electric field forces and iron winds are generated by needle,circle and plate electrodes respectively in different electrodes heights under both AC and DC fields though experiments. Experimental results showed that the flame characteristics are affected by needle electrodes mainly through the action of ion wind,by plate type electrodes mainly through the action of electric field force and by annular electrodes through both the electric field force and ion wind at the same time. Under DC field 's effects of all electrodes types,the flame will consequently go down while the voltage reached to a limit value,and it will breakdown under the strong effect of the ion wind by needle electrodes. The results also showed the influence by different electrodes types to the current characteristics,resistance properties and configuration of themicro-scale flames.

Effect of Blending Ratio on Properties of Core Yarn and Fabric of Polysulfonamide(PSA)/Flame Retardant Viscose(FRV)/Conductive Filament

In order to develop a fabric with excellent flame resistance function,antistatic function,moisture absorption and breathability,the polysulfonamide(PSA)fiber and the flame retardant viscose(FRV)fiber were blended.Meanwhile,the conductive filaments were used as the core yarn,and then they were made into the core-spun yarn and the fabric at different blending ratios of PSA/FRV.The effects of the blending ratio of PSA/FRV on the mechanical properties and the evenness of the yarn were studied.The effects of the blending ratio of PSA/FRV on mechanical properties,flame retardant properties,antistatic properties,moisture permeability and drape of the fabric were analyzed.With the increase of the blending ratios of PSA/FRV,the strength and the elongation of the core-spun yarn increased firstly and then decreased.Moreover,the evenness of the core-spun yarn was improved,the fabric strength increased firstly and then decreased,the flame resistance decreased,and the antistatic performance improved.These results provide an important basis for the preparation and wide application of fabrics made of PSA/FRV/conductive filament.

Thermal Protective Performance of Heat and Flame Resistant Fabrics in Different Radiant and Convective Heat Exposures

The thermal protective performance （TPP） is important for heat and flame resistant fabrics. In this study, fabrics which are made of flame resistant cotton, Nomex, polybenzimidazole （PBI）, polysulfonamide （PSA）, kermel, and blend of kermei with rayon fiber are investigated on high intensity of different radiant and convective heat source. The mechanism of heat transfer in different situations is discussed. It is identified that exposed candition has an important effect on thermal protective performance. TPP rating increases with the increasing percentage of convective heat.

Micro-organic dust combustion considering particles thermal resistance

Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.

An Improved Heat Transfer Model for Flame Resistant Fabric Used in Thermal Protective Clothing

An improved numerical heat transfer model considering pyrolysis effect is proposed to predict thermal performance of heat-resistant fabric subjected to radiant heat flux. The model incorporates the heat-induced changes in fabric thermophysical properties. The new model has been validated with data from modified Radiant Protective Performance (RPP) tests of flame-resistant cotton fabrics. Comparison with experimental data shows that the predictions of mass loss rates and temperature profiles within the charring material and skin simulant are in reasonably good agreement with the experiments. Results from the numerical model contribute to a better understanding of the heat transfer process within flame-resistant fabrics under high heat flux conditions, and also to establish a systematic method for analyzing heat transfer in other fibrous materials applications.

Fire Intumescent,High-Temperature Resistant,Mechanically Flexible Graphene Oxide Network for Exceptional Fire Shielding and Ultra-Fast Fire Warning

Smart fire alarm sensor(FAS)materials with mechanically robust,excellent flame retardancy as well as ultra-sensitive temperature-responsive capability are highly attractive platforms for fire safety application.However,most reported FAS materials can hardly provide sensitive,continuous and reliable alarm signal output due to their undesirable temperature-responsive,flame-resistant and mechanical performances.To overcome these hurdles,herein,we utilize the multi-amino molecule,named HCPA,that can serve as triple-roles including cross-linker,fire retardant and reducing agent for decorating graphene oxide(GO)sheets and obtaining the GO/HCPA hybrid networks.Benefiting from the formation of multi-interactions in hybrid network,the optimized GO/HCPA network exhibits significant increment in mechanical strength,e.g.,tensile strength and toughness increase of~2.3and~5.7 times,respectively,compared to the control one.More importantly,based on P and N doping and promoting thermal reduction effect on GO network,the excellent flame retardancy(withstanding~1200℃flame attack),ultra-fast fire alarm response time(~0.6 s)and ultra-long alarming period(>600 s)are obtained,representing the best comprehensive performance of GO-based FAS counterparts.Furthermore,based on GO/HCPA network,the fireproof coating is constructed and applied in polymer foam and exhibited exceptional fire shielding performance.This work provides a new idea for designing and fabricating desirable FAS materials and fireproof coatings.

Properties of Esterified Wood Prepared with Maleic Anhydride/Tetrabr Omophthalic Anhydride/Glycerol Mixture

For overcoming disadvantages of wood, an esterification process was employed and tetrabromophthalic anhydride (TBPA) was used as a reactive chemical agent to prepare an esterified wood with the high dimensional stability, flame resistance, and resistance to biodegradation from water-leaching. The experimental results indicated that esterification of wood plus maleic anhydride / tetrabromophthalic anhydride / glycerol could endow wood with dimensional stability, the antiswelling efficiency during water absorption (ASEw), reduction in water absorptivity (RWA), antiswelling efficiency during moisture absorption (ASEm), moisture excluding efficiency (MEE), and oxygen index (OI) of treated wood increased with an increase in the weight percent gain (WPG). And the treated wood showed great decay resistance and resistance to water leaching, too.

Antibacterial and anti-flaming PA6 composite with metathetically prepared nano AgCl@BaSO_(4) co-precipitates

In this study,a facile and environmentally friendly method with low energy consumption for preparing nanoscale AgCl and BaSO4 co-precipitates(AgCl@BaSO_(4) co-precipitates)was developed based on the metathetical reaction.Then,the dried co-precipitates were melt-compounded with polyamide 6(PA6)resins at a specified mass ratio in a twin-screw extruder.The results demonstrated that in the absence of any coating agent or carrier,the nanoparticles of AgCl@BaSO_(4) co-precipitates were homogeneously dispersed in the PA6 matrix.Further analysis showed that after the addition of AgCl@BaSO_(4) co-precipitates,the antibacterial performance,along with the flame-retardance and anti-dripping characteristics of PA6,was enhanced significantly.In addition,the PA6 composites possessed high spinnability in producing pre-oriented yarn.

Nonflammable PVDF-based gel polymer electrolytes modified by dimethyl methylphosphate for wide temperature range,long cycle-life and high-safety lithium metal batteries

Gel polymer electrolytes(GPEs)has been considered as a promising candidate for the development of lithium metal batteries(LMBs)with high energy density and high safety,yet most reported GPEs is flammable,making the LMBs still facing great safety hazards.Herein,we used dimethyl methylphosphate(DMMP)as the functional flame retardant and plasticizer for poly(vinylidene fluoride)(PVDF)matrix to develop a novel nonflammable PVDF-DMMP GPEs for LMBs.The DMMP not only highly enhances the flame resistance of PVDF-DMMP GPEs,the efficient dissociation of lithium salt and the rapid transport of lithium ions,but also helps to form stable and robust CEI/SEI layers.As a result,the ultrathin PVDF-DMMP GPEs(∼20µm)present superb flame resistance,high ionic conductivity(1.34×10^(−3) S cm^(−1) at 30℃),fast lithium ion transport(t_(Li^(+))=0.59at 30℃),high electrochemical stability voltage window(over 4 V)at 30–80℃ and uniform lithium deposition.When used in Li∥Li symmetric cells,Li∥LiFePO_(4)(LFP)and Li∥LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) full cells,the nonflammable PVDF-DMMP GPEs could endow these cells with long-term cycle stability,high rate capability,wide-temperature operation ranges(from−20 to 80℃)and high safety simultaneously.Even when suffering from harsh deconstructive tests,the Li∣PVDF-DMMP GPEs∣LFP pouch cells still work normally without any safety hazards.The actual energy density of the packed pouch cell is as high as 508 Wh kg^(−1).Therefore,our work can provide a promising strategy for the design of high safety and high-energy-density LMBs.