聚合物/无机物纳米复合材料的阻燃性研究

本文详细介绍近年来问世的无机纳米填料,包括碳纳米管(CNT)、层状氧化石墨(LGO)、纳米蒙脱土(MMT)、多面低聚硅倍半氧烷(POSS)等复合材料的研究进展及阻燃性能特点.分析了当前阻燃聚合物/无机物纳米复合材料基础研究和应用中存在的问题,展望阻燃聚合物/无机物纳米复合材料研究的发展趋势,并讨论了若干阻燃聚合物纳米复合材料的前沿问题.     

A novel halogen‐free intumescent flame retardant containing phosphorus and nitrogen and its application in polypropylene systems

A novel halogen‐free intumescent flame retardant, pentaerythritol spirobisphosphoryl‐dicyandiamide (SPDC), was synthesized and characterized by FTIR, ¹H NMR, and ³¹P NMR spectra. The new flame retardant was used in polypropylene (PP) to prepare flame‐retardant materials whose flammability and thermal behavior were studied by the limiting oxygen index (LOI) method, thermogravimetric analysis (TGA), and cone calorimetry (CONE). The mechanical properties were also investigated. The results indicated that when the addition of SPDC reached 30 wt%, the material showed both excellent flame retardancy and anti‐dripping abilities for PP. Moreover, the LOI value of the PP‐IFR(30%) was 32.5, and it passed the UL‐94 V‐0 rating test. The CONE results revealed that in PP, SPDC(30%) significantly decreased the peak heat release, total heat release, and smoke relative to their values for pure PP. The morphological structures observed by SEM demonstrated that SPDC could promote the formation of a homogeneous and compact intumescent char layer. The TGA data showed that SPDC could enhance the thermal stability of PP and effectively increase the char residue formation. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Preparation and investigation of ethylene–vinyl acetate copolymer/silicone rubber/clay nanocomposites

In this article, the combination of silicone rubber (SR) elastomer with synthetic iron montmorillonite (Fe‐MMT) to form a kind of new flame‐retardant system based on an ethylene–vinyl acetate (EVA) copolymer is first reported. Also, the flame retardancy of the EVA/SR/Fe‐MMT hybrid are compared with that of EVA/SR/natural sodium montmorillonite. The structures of the nanocomposites were characterized with X‐ray diffraction and transmission electron microscopy. Cone calorimeter tests and thermogravimetric analysis were used to evaluate the flame‐retardant properties and thermal stability of the composites, respectively. In addition, tensile tests were carried out with a universal testing machine, and the morphology of the fracture surface was observed with environmental scanning electron microscopy. We found that SR/organophilic montmorillonite (Fe‐OMT) was more effective in reducing the primary peak heat release rate of the nanocomposite, and the EVA/SR/Fe‐OMT hybrid had a higher thermal stability in the deacetylated polymer than EVA/SR/sodium organophilic montmorillonite. Moreover, the exfoliated EVA/SR/Fe‐OMT nanocomposite displayed excellent mechanical properties because of a better dispersion of Fe‐OMT in the polymer matrix, and a possible mechanism is discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Flame‐retardant mechanism of expandable polystyrene foam with a macromolecular nitrogen–phosphorus intumescent flame retardant

Expandable polystyrene (EPS) foam is largely used as the thermally insulating external wall in buildings and constructions, but it is extremely flammable because of the presence of almost 98% air into its porous structure, its high surface‐area‐to‐mass ratio, and its elemental composition. Lots of serious fire disasters caused by EPS foam have posed great threats to people's properties and lives in recent years. Thus, a halogen‐free, flame‐retardant EPS is urgently needed, and its preparation is still a global challenge. To solve the problem that it is easy for EPS foam to form melt dripping and difficult for it to generate a char layer during the combustion process, a macromolecular nitrogen–phosphorus intumescent flame retardant (MNP) was selected to prepare flame‐retardant EPS foam and good mechanical and flame‐retardant properties were obtained. The scanning electron microscopy characterization revealed that MNP could penetrate into the gap between the beads, and a thin physical coating layer formed on the surface of the bead. The data from the thermogravimetry–Fourier transform infrared test indicated that a nitrogenous noncombustible gas was generated by the pyrolysis of MNP. When the MNP content increased to 30%, the limiting oxygen index and the smoking density rate of the EPS–MNP foam were 28.8 and 23.6, respectively, and a UL94 V‐0 classification was achieved. In addition, the heat‐release rate, total heat‐release, smoke produce rate, and carbon dioxide production of the EPS–MNP foams all decreased obviously; this was attributed to the flame‐retardant effects of MNP in both the condensed and gas phases. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44356.     

不同POSS对磷⁃硅协同阻燃环氧树脂性能的影响

将两种多面体低聚倍半硅氧烷(POSS)分别与9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)基有机磷阻燃剂(D-bp)复配,制备了磷-硅协同阻燃环氧树脂,并对其阻燃、热、力学和动态力学性能等进行分析.结果表明,在磷含量仅为0.25％(质量分数,下同)时,磷-硅协同阻燃环氧树脂就能达到UL 94 V-0级...     

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry     

Condensed‐phase flame retardation in nylon 6‐layered silicate nanocomposites: Films,fibers, and fabrics

Flame‐retardant properties of nylon 6/organically modified montmorillonite (OMMT) thin films, fibers, and fabrics were investigated to determine the efficacy of condensed‐phase flame‐retardant mechanism in relation to montmorillonite concentration, sample geometry, and flame test conditions. Horizontal flame spread conducted on thin films revealed no significant difference in burning behavior between nylon 6 and nanocomposites with 5 wt% OMMT. However, with a higher concentration level of 8–10 wt% OMMT, the films burned without any dripping. The flame spread rate was reduced by 30–40% as compared with nylon 6 films. Cone calorimeter study on nanocomposite films showed that the peak heat release rate of nylon 6 was reduced by 65–67% with 8–10 wt% OMMT. Undrawn nanocomposite monofilaments with 10 wt% OMMT burned slowly and steadily in Bunsen flame without dripping. In cone calorimeter, nanocomposite fabrics with 8 wt% OMMT showed reduced heat release rate and mass loss rate compared to nylon 6 fabrics with increase in fabric tightness factor. The mass loss rate was about 40–60% less when compared with nylon 6 fabrics. The fabric char structure remained intact after burning. This demonstrated the interdependence of fabric tightness factor, OMMT concentration, and source of heat flux in forming a protective char and affecting the flammability of fabrics. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Flame Retardancy and Thermal Performance of Polypropylene Treated With the Intumescent Flame Retardant,Piperazine Spirocyclic Phosphoramidate

Piperazine spirocyclic phosphoramidate (PSP), a novel halogen‐free intumescent flame retardant, was synthesized and used to improve the flame retardancy and dripping resistance of polypropylene (PP) combined with ammonium polyphosphate (APP) and a triazine polymer charring‐foaming agent (CFA). The optimum flame‐retardant formulation was PSP:APP:CFA = 3:6:2 (weight ratio). The flammability and thermal behavior of the (intumescent flame‐retardant)‐PP (IFR‐PP) were investigated via limiting oxygen index (LOI), vertical burning tests (UL‐94), thermogravimetric analysis, and cone calorimetry (CONE). The results indicated that the IFR‐PP had both excellent flame retardancy and anti‐dripping ability. The optimum flame‐retardant formulation gave an LOI value of 39.8 and a UL‐94 V‐0 rating to PP. Moreover, both the heat release rate and the total heat release of the IFR‐PP with the optimum formulation decreased significantly relative to those of pure PP, according to the cone calorimeter analyses. The residues of IFR‐PP obtained after CONE tests were observed by scanning electron microscopy, and it was found that the char yield was directly related to the flame retardancy and anti‐dripping behavior of the treated PP. J. VINYL ADDIT. TECHNOL., 20:10–15, 2014. © 2014 Society of Plastics Engineers     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Studies on intumescent flame retardant polypropylene composites based on biodegradable wheat straw

Wheat straw (WS) has numerous advantages compared with traditional bioadditives such as starch and lignin. So in this work, based on WS and silica microencapsulated ammonium polyphosphate, flame retardant polypropylene/wheat straw (WSP) composites were prepared by melted blend method. Flame retardant and thermal properties of WSP composites have been investigated. The results of cone calorimeter show that peaks of heat release rate and total heat release of the flame retardant WSP composite decrease substantially compared with those of pure polypropylene. The peak of heat release rate value of the flame retardant WSP composite decreases from 1290.5 to 247.9 kW/m², and the total heat release value decreases from 119.4 to 46.3 MJ/m². Meanwhile, thermal degradation and gas products of the flame retardant WSP composite were monitored by thermogravimetric analysis and thermogravimetric analysis‐infrared spectrometry. The result of thermal analysis shows that the flame retardant WSP composite has a high thermal stability and has a 30.0 wt% residual char at 600°C. From this work, we hope to provide a method to prepare flame retardant polymer composites with a biodegradable natural material‐WS.     

Flame‐retardant materials: synergistic effect of halloysite nanotubes on the flammability properties of acrylonitrile–butadiene–styrene composites

Novel well‐dispersed nanocomposites of halloysite nanotubes and acrylonitrile–butadiene–styrene were prepared. The fire retardancy and thermal stability of these new nanocomposites were improved. A synergistic effect was observed between the halloysite nanotubes and an intumescent flame‐retardant system consisting of ammonium polyphosphate, melamine polyphosphate and pentaerythritol in the acrylonitrile–butadiene–styrene composites. The incorporation of the intumescent flame‐retardant material into the halloysite–polymer nanocomposite system also improved the thermal stability and reduced the peak heat release rate by up to 56.2%, and it significantly reduced the emission of CO and CO₂ gases. The morphology and dispersion of the halloysite nanotubes were characterized using scanning and transmission electron microscopy. The thermal stability and flammability properties were investigated using thermogravimetric analysis and cone calorimeter tests. © 2013 Society of Chemical Industry     

高聚物中纳米填料与无卤阻燃剂间的相互作用

根据新近发表的文献,综述环氧树脂/间苯二酚双(二苯基磷酸酯)/蒙脱石(EP/RDP/MMT),聚苯乙烯(PS)/芳香族磷酸酯(ArP)/MMT,乙烯-乙酸乙烯共聚物(EVA)/氢氧化物(MH)/MMT及聚苯乙烯/间苯二酚四苯基双磷酸酯/碳钠米管(PS/RDP/CNT)四个系统中纳米填料与无卤阻燃剂的相互作用。结果表明,除EP/RDP/MMT系统在阻燃性上可能有一定的对抗作用外,其他系统在热稳定性及阻燃性上均有一定的协效作用。     

Flame retardancy of nanocomposites

Nishizawa Technical Institute (NTI) and Kyoto Institute of Technology (KIT) have developed EVA‐clay nanocomposites with excellent mechanical and flame retardant properties by a reactive process and have succeeded in a novel method to synthesize an aluminium hydroxide nanoparticle, which has the effect of improving the flame retardancy of nanocomposites with EVA. About the EVA‐clay nanocomposites, the peak heat release rate (HRR) of sample MM2 (EVA‐clay partially processed nanocomposites) and sample MM3 (EVA‐clay completely processed nanocomposites) was reduced from 1/3 (one third) to 1/4 (one fourth) compared with EVA only. Sample AL‐1 (EVA‐aluminium nanocomposites) showed a more effective reduction of HRR than sample AL‐2 (EVA‐normal aluminium hydroxide). Beside these experiments, the orientation of the nanofiller MMT (montmorillonite) by a 2‐axis extruder equipped a special novel kneading roll head and the flame retardancy of silica nanocomposite coating materials (Sol‐Gel process) is discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

PVC/montmorillonite nanocomposites based on a thermally stable,rigid‐rod aromatic amine modifier

Two kinds of polyvinyl chloride (PVC)/montmorillonite (MMT) nanocomposites were prepared by the melt intercalation method based on a thermally stable, rigid‐rod aromatic amine modifier and a commonly used 1‐hexadecylamine. The information on morphological structure of PVC/MMT nanocomposites was obtained using XRD and TEM. The mechanical, thermal, and flame retardant properties of the nanocomposites were characterized by universal tester, DMA, TGA, and cone calorimeter. The degree of degradation of PVC was studied by ¹H‐NMR. MMT treated by the aromatic amine exhibited better dispersibility than that treated by 1‐hexadecylamine. The nanocomposites, based on this MMT, consequently exhibited better mechanical, thermal, and flame retardant properties and lower degradation degree than those based on 1‐hexadecylamine‐treated MMT. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 567–575, 2004     

A Novel Phosphorus‐Containing Poly(ethylene terephthalate) Nanocomposite with Both Flame Retardancy and Anti‐Dripping Effects

Summary: It is a big challenge to improve simultaneously both the flame retardancy and the melt‐dripping resistance of polymeric materials such as PET. In this paper, a novel intumescent flame retardant, DPSPB, was synthesized and blended with copolyester PET‐co‐DDP/O‐MMT nanocomposites, which were synthesized by polycondensation of TPA, EG, DDP, and O‐MMT. The resulting PET‐co‐DDP/O‐MMT/DPSPB nanocomposites exhibit very good flame retardance and dripping resistance, e.g., LOI = 29, UL‐94 V‐0. SEM, XRD, and XPS were used to investigate the relationships between the structures and properties of the composites. It is proved that DPSPB offers excellent protection for the structure of nanocomposites, which is responsible for the good anti‐dripping properties of the nanocomposites.

Residues of copolyesters after combustion: common nanocomposite residue of PDMN (left) and the novel nanocomposite residue of PDMN/DPSPB (right).     

Intumescent flame retardation of melamine‐modified montmorillonite on polyamide 6: Enhancement of condense phase and flame retardance

Melamine‐modified montmorillonite (MA‐MMT) was prepared via cation exchange. The intercalation behavior was investigated by Fourier transform infrared spectrometer (FT‐IR), X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction (XRD). The results showed that the d‐spacing value increased from 1.25 nm for Na‐montmorillonite (Na⁺MMT) to 1.53 nm for MA‐MMT. Different kinds of montmorillonite combined with melamine pyrophosphate (MPP) were used to prepare flame‐retardant polyamide 6 (FR‐PA6). Flame retardance of FR‐PA6 samples was investigated by limiting oxygen index (LOI), UL‐94 vertical burning method, and cone calorimeter test. Morphology and component of char residues for FR‐PA6 were investigated by scanning electron microscope (SEM) and XPS. It was found that MA‐MMT/MPP system contributed both excellent flame retardance and anti‐dripping ability for PA6. MA‐MMT particles can fill flaws of char residues and strengthen the char layer, leading to form more intumescent char layer. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Structure–property relationships in nylon 6 nanocomposites based on octaphenyl‐, dodecaphenyl–POSS,montmorillonite, and their combinations

Binary and ternary nanocomposites were produced by incorporating, via melt compounding, two types of octa‐ and dodecaphenyl substituted polyhedral oligomeric silsesquioxanes (POSS), montmorillonite (MMT), and combinations of POSS with MMT into nylon 6. The tensile, flexural, and dynamic thermo‐mechanical properties of these materials were characterized and their structure–property relationships discussed. The results show that the losses in ductility and toughness experienced after inclusion of MMT into nylon 6 can be balanced out by co‐mixing MMT with the dodecaphenyl–POSS to produce a ternary nanocomposite. This trend however was less pronounced in the ternary MMT/octaphenyl–POSS system. Analysis of the microstructure organization in these materials using XRD and SEM sheds some light on understanding the differences in behavior. Both types of POSS particles mixed alone in nylon 6 were found to be polydisperse (500 nm to a few microns in size) and locally aggregated, yielding materials with similar mechanical performance. The co‐mixing of MMT with the octaphenyl–POSS served to break down the POSS crystal aggregates, enhancing their micro‐mechanical reinforcing action. On the other hand, the POSS crystals were not affected in the MMT/dodecaphenyl–POSS system, which led to improving their toughening ability. POLYM. COMPOS., 36:153–160, 2015. © 2014 Society of Plastics Engineers     

Flame retardancy and mechanical properties of polyamide 6 with melamine polyphosphate and ionic liquid surfactant‐treated montmorillonite

The mechanical properties and inflammability of polyamide 6 (PA6) nanocomposites incorporated with Montmorillonite organoclay (MMT) modified with thermal stable ionic liquid surfactants were investigated. The compatibility between ionic liquid‐treated MMT and PA6 matrix was improved and the intercalation morphology was achieved, which resulted in the increaseof tensile modulus. However, the addition of organo‐MMTs alone did not improve the inflammability of the PA6 nanocomposite, because of strong melt‐dripping behavior of PA6 matrix. Addition of auxiliary melamine polyphosphate (MPP) intumescent flame retardant to the nanocomposite prevented the melt dripping and enhanced inflammability performance. The enhanced inflammability of PA6/organoclay/MPP nanocomposites was attributed to the synergistic effect between imidazolium or phosphonium organo‐MMTs and intumescent flame retardant MPP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40648.     

Flame‐retarding mechanism of organically modified montmorillonite and phosphorous‐Nitrogen flame retardants for the preparation of a halogen‐free,flame‐retarding thermoplastic poly(ester ether) elastomer

In this study, thermoplastic poly(ester ether) elastomer (TPEE) nanocomposites with phosphorus–nitrogen (P–N) flame retardants and montmorillonite (MMT) were prepared by melt blending. The fire resistance of the nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL 94) tests. The results show that the addition of the P–N flame retardants increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants only obtained a UL 94 V‐2 ranking; this resulted in a flame dripping phenomenon. On the other hand, TPEE containing the P–N flame retardant and organically modified montmorillonite (o‐MMT) achieved better thermal stability and good flame retardancy; this was ascribed to its partially intercalated structure. The synergistic effect and synergism were investigated by Fourier transform infrared spectroscopy and thermogravimetry. The introduction of o‐MMT decreased the inhibition action of the P–N flame retardant and increased the amount of residues. The catalytic decomposition effect of MMT and the barrier effect of the layer silicates are discussed in this article. The residues after heating in the muffle furnace were analyzed by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and laser Raman spectroscopy. It was shown that the intercalated layer silicate structure facilitated the crosslinking interaction and promoted the formation of additional carbonaceous char residues in the formation of the compact, dense, folded‐structure surface char. The combination of the P–N flame retardant and o‐MMT in TPEE resulted in a better thermal stability and fire resistance because of the synergistic effect of the mixture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41094.     

Performance enhancement of polylactide by nanoblending with POSS and graphene oxide

We report the effect of filler modification on the properties of polylactide (PLA)‐based nanocomposites, where graphene oxide (GO) nanosheets and polyhedral oligomeric silsesquioxane (POSS) nanocages are employed as nanofillers. The organically treated nanofillers are termed as GO‐functionalized and POSS‐functionalized. The synthesis of the nanocomposites was carried out via in situ ring‐opening polymerization of lactic acid (LA). The following four naocomposite systems were prepared, characterized, and compared to achieve a better understanding of structure‐property relationship (1) PLA/GO‐functionalized, (2) PLA/POSS‐functionalized, (3) PLA/physical mixture of GO‐functionalized and POSS‐functionalized, and (4) PLA/GO‐graft‐POSS (with eight hydroxyl groups). As revealed by the thermal and mechanical (nanoindendation) characterization, that the nanocomposites having a combination of GO and POSS as nanofiller, either as physical mixture of GO‐functionalized and POSS‐functionalized or as GO‐graft‐POSS, is far more superior as compared with the nanocomposites having individually dispersed nanofillers in the PLA matrix. Observed enhancement is attributing to the synergistic effect of the nanofillers as well as better dispersion of the modified‐fillers in the matrix. POLYM. COMPOS., 35:118–126, 2014. © 2013 Society of Plastics Engineers