The polymer-layered silicate nanocom- posites (PLSN) are preparedby the polymer melt interca- lation in layered silicate. By theanalyses of XRD, DSC, IR, NMR and Ac in pedance measurements etc, theex- Perimental resul...The polymer-layered silicate nanocom- posites (PLSN) are preparedby the polymer melt interca- lation in layered silicate. By theanalyses of XRD, DSC, IR, NMR and Ac in pedance measurements etc, theex- Perimental results show that polymer (PEO) can intercalate Intothe silicate interlayer in melt state, which leads to the Addition ofthe repeated distance of silicate.展开更多
To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic s...To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.展开更多
Polymer nanocomposites are a new class of flame retarded materials which have attracted much attention and considered as a revolutionary new flame retardant approach.A very small amount of nano flame retardants (norma...Polymer nanocomposites are a new class of flame retarded materials which have attracted much attention and considered as a revolutionary new flame retardant approach.A very small amount of nano flame retardants (normally < 5 wt%) can significantly reduce the heat release rate (HRR) and smoke emission (SEA) during the combustion of polymer materials.Moreover,the addition of nano flame retardants can also improve the mechanical properties of polymer materials compared with the deterioration of traditional flame retardants.This paper reviews the recent development in the flame retardant field of polymer nanocomposites and also introduces the related research in our lab.The challenges and problems are discussed and the future development of flame retarded polymer nanocomposites is prospected.展开更多
The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing...The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing attention due to low commercial cost and easy fabrication craft.However,traditional additive-type flame retardants usually need high addition amount to achieve a desirable effect which causes many side-effects on the overall performance of polymer materials,such as deteriorated mechanical property and processability.At present two-dimensional(2D)nanomaterials have also been applied to reduce the fire hazards of polymer(nano)composites with the coupling of barrier function and catalysis as well as carbonization effect.Even though most research work mainly focus on graphene-based flame retardants,more emerging two-dimensional nanomaterials are taking away research attention,due to their complementary and unique properties,mainly including hexagonal boron nitride(h-BN),molybdenum disulfide(MoS2),metal organic frameworks(MOF),carbon nitride(CN),titanium carbide(MXene)and black phosphorene(BP).In this review,except for graphene,the flame retardant mechanism involving different layered nanomaterials are also reviewed.Meanwhile,the functionalization method and flame retardancy effect of different layered nanomaterials are emphatically discussed for offering an effective reference to solve the fire hazards of polymer materials.Moreover,this work objectively evaluates the practical significance of polymer/layered nanomaterials composites for industrial application.展开更多
Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood ...Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.展开更多
为了赋予涤/棉混纺织物良好的阻燃性能,以pH值为5、质量分数为1%壳聚糖溶液和pH值为2、质量分数为1.5%植酸钠溶液,通过静电层层自组装法,对经多巴胺改性后的涤/棉(65/35)混纺织物进行阻燃整理。其中正负离子交替沉积1次记为组装1层,第1...为了赋予涤/棉混纺织物良好的阻燃性能,以pH值为5、质量分数为1%壳聚糖溶液和pH值为2、质量分数为1.5%植酸钠溶液,通过静电层层自组装法,对经多巴胺改性后的涤/棉(65/35)混纺织物进行阻燃整理。其中正负离子交替沉积1次记为组装1层,第1层内每次组装15 min,第1层后各次组装时间为5 min,共组装15层。探讨了整理后织物极限氧指数(LOI)、炭长、热重、热释放速率、炭渣形貌等性能。结果表明:多巴胺改性可以提高涤/棉混纺织物的反应性,有利于阻燃整理;整理后织物阻燃性能显著提高,LOI值从未整理时的18.8%提高到28.7%;热分解温度比未整理织物大幅提前,炭渣含量较未整理提高了5.7%;整理后织物点燃时间延长,平均热释放速率(HRR)和峰值热释放速率(PHRR)分别为14.16 k W/m2和51.07 k W/m2,相较未整理涤/棉织物下降了84.62%和78.47%,织物燃烧危险性显著降低。展开更多
基金This project was supported by the National Natural Science Foundation of China Wuhan Youth Foundation
文摘The polymer-layered silicate nanocom- posites (PLSN) are preparedby the polymer melt interca- lation in layered silicate. By theanalyses of XRD, DSC, IR, NMR and Ac in pedance measurements etc, theex- Perimental results show that polymer (PEO) can intercalate Intothe silicate interlayer in melt state, which leads to the Addition ofthe repeated distance of silicate.
基金the Scientific Research Project of Hunan Provincial Education Department,China(21B0238)Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology,China(2019RS2040)+1 种基金National Natural Science Foundation of China(32171708)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.
基金financially supported by the National Natural Science Foundation of China (50873092 and 51073140)
文摘Polymer nanocomposites are a new class of flame retarded materials which have attracted much attention and considered as a revolutionary new flame retardant approach.A very small amount of nano flame retardants (normally < 5 wt%) can significantly reduce the heat release rate (HRR) and smoke emission (SEA) during the combustion of polymer materials.Moreover,the addition of nano flame retardants can also improve the mechanical properties of polymer materials compared with the deterioration of traditional flame retardants.This paper reviews the recent development in the flame retardant field of polymer nanocomposites and also introduces the related research in our lab.The challenges and problems are discussed and the future development of flame retarded polymer nanocomposites is prospected.
基金the National Natural Science Foundation of China(Nos.51761135113,51911530127 and 51973203)the Fundamental Research Funds for the Central Universities(No.WK2320000043).
文摘The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing attention due to low commercial cost and easy fabrication craft.However,traditional additive-type flame retardants usually need high addition amount to achieve a desirable effect which causes many side-effects on the overall performance of polymer materials,such as deteriorated mechanical property and processability.At present two-dimensional(2D)nanomaterials have also been applied to reduce the fire hazards of polymer(nano)composites with the coupling of barrier function and catalysis as well as carbonization effect.Even though most research work mainly focus on graphene-based flame retardants,more emerging two-dimensional nanomaterials are taking away research attention,due to their complementary and unique properties,mainly including hexagonal boron nitride(h-BN),molybdenum disulfide(MoS2),metal organic frameworks(MOF),carbon nitride(CN),titanium carbide(MXene)and black phosphorene(BP).In this review,except for graphene,the flame retardant mechanism involving different layered nanomaterials are also reviewed.Meanwhile,the functionalization method and flame retardancy effect of different layered nanomaterials are emphatically discussed for offering an effective reference to solve the fire hazards of polymer materials.Moreover,this work objectively evaluates the practical significance of polymer/layered nanomaterials composites for industrial application.
基金This work was financially supported by National Natural Science Foundation of China(32201485)Natural Science Foundation of Hunan Province,China(2022JJ40863)+1 种基金Scientific Research Project of Hunan Provincial Education Department,China(21B0238)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.
文摘为了赋予涤/棉混纺织物良好的阻燃性能,以pH值为5、质量分数为1%壳聚糖溶液和pH值为2、质量分数为1.5%植酸钠溶液,通过静电层层自组装法,对经多巴胺改性后的涤/棉(65/35)混纺织物进行阻燃整理。其中正负离子交替沉积1次记为组装1层,第1层内每次组装15 min,第1层后各次组装时间为5 min,共组装15层。探讨了整理后织物极限氧指数(LOI)、炭长、热重、热释放速率、炭渣形貌等性能。结果表明:多巴胺改性可以提高涤/棉混纺织物的反应性,有利于阻燃整理;整理后织物阻燃性能显著提高,LOI值从未整理时的18.8%提高到28.7%;热分解温度比未整理织物大幅提前,炭渣含量较未整理提高了5.7%;整理后织物点燃时间延长,平均热释放速率(HRR)和峰值热释放速率(PHRR)分别为14.16 k W/m2和51.07 k W/m2,相较未整理涤/棉织物下降了84.62%和78.47%,织物燃烧危险性显著降低。
