无机填料填充PE-LD/EVA合金的导热及阻燃性能

采用氧化铝（Al2O3）为导热填料、氢氧化镁［Mg(OH)2］为阻燃填料,以低密度聚乙烯（PE-LD）和乙烯醋酸乙烯共聚物（EVA）为基体树脂制备导热阻燃复合材料。通过导热性能测试、燃烧行为表征（极限氧指数和垂直燃烧测试）以及热重分析研究了PE LD/EVA/Al2O3/Mg(OH)2复合材料的导热性能、阻燃性能及热稳定性。结果表明,含有50份Al2O3及50份Mg(OH)2的复合材料,在PE-LD/EVA质量比为1/1时,热导率可达到1.21 W/m·K;材料的阻燃性能及热稳定性都随 EVA 含量的增加而增大,极限氧指数从27.0 % 提高到31.5 %,UL 94 垂直燃烧从无等级提高到V-0级,残炭率从46.5 %提高到57.7 %。     

LDPE/EVA/Mg(OH)2阻燃复合材料流变行为的研究

借助HAAKE RHEOCORD 90流变仪分别在140℃、160℃、和180℃3个温度下，研究了LDPE／EVA和LDPE／EVA／Mg(OH)2阻燃复合材料的流变行为。研究结果表明：LDPE／EVA／Mg(OH)2阻燃复合材料的熔体流动行为同LDPE／EVA一样，仍属于非牛顿型假塑性流体流动行为。不同剪切速率下，LDPE／EVA／Mg(OH)2阻燃复合材料与LDPE／EVA粘流活化能相差很小，说明LDPE／EVA／Mg(OH)2阻燃复合材料与LDPE／EVA一样，其熔体粘度对温度不十分敏感。相同温度下，LDPE／EVA／Mg(OH）2阻燃复合材料的挤出膨胀比低于LDPE／EVA，这一特性说明LDPE／EVA／Mg(OH)2阻燃复合材料制品尺寸稳定性较LDPE／EVA有所提高。     

表面原位化学组合改性Al（OH）3／PVC复合材料的制备与性能

基于Al(OH)_3粉体与PVC基体的界面设计和调控,采用表面原位化学组合改性方法,在Al(OH)_3表面依次化学键合烷基酚醛树脂、丁腈橡胶等几种大分子改性剂,形成极性逐渐过渡的梯度界面层。当改性Al(OH)_3在PVC复合材料中的用量为80份时,材料的缺口冲击强度达到最大值,分别为添加等量偶联剂改性Al(OH)_3、未改性Al (OH)_3复合材料的2．5和2．7倍,是基体树脂的1．5倍,获得了具有高阻燃消烟性能,同时改善了力学和加工性能的综合性能良好的高填充复合材料。通过扫描电镜分析表明,Al(OH)_3粒子经过表面原位化学组合方法处理,在PVC中分散均匀,与塑料基体结合良好,并形成了以Al(OH)_3粒子为核、以多层大分子改性剂为壳的软壳硬核结构。     

LDPE／EVA／Mg（OH）2阻燃复合材料流变行为的研究

借助HAAKE RHEOCORD90流变仪分别在140℃、160℃和180℃三个温度下．研究了LDPE/EVA和LDPE/EVA／Mg(OH)2阻燃复合材料的流变行为。研究结果表明：LDPE/EVA/Mg(OH)2阻燃复合材料的熔体流动行为同LDPE／EVA一样．仍属于非牛顿型假塑性流体流动行为。不同剪切速率下，LDPE/EVA/Mg(OH)2阻燃复合材料与LDPE／EVA粘流活化能相差很小．说明LOPE／EVA/Mg(OH)2阻燃复合材料与LOPE/EVA一样．其熔点粘度对温度不十分敏感。相同温度下，LDPE／EVA/Mg(OH)2阻燃复合材料的挤出膨胀比低于LDPE／EVA，这一特性说明LDPE/EVA/Mg(OH)2阻燃复合材料制品尺寸稳定性较LOPE／EVA有所提高。     

原位形成FPP偶联Al(OH)3/PP中的界面相互作用研究

制备低含量Al(OH)3填充PP复合材料[Al(OH)3/PP]，研究原位形成的官能团化聚丙烯（FPP）在Al(OH)3/PP中的结晶、熔融行为，结晶形态，以及与各组分间的相互作用。研究认为，在复合材料中存在Al(OH)3与FPP间的化学作用，FPP与PP的相容与共结晶作用，Al(OH)3表面异相诱导成核作用，FPP对Al(OH)3表面异相诱导成核作用的活化作用等，从而改善了Al(OH)3/PP的物理与力学性能。     

超微细改性Al(OH)3填充LDPE/EVA的研究

Al(OH）3是LDPE／EVA主要的阻燃，消烟填充剂。研究了不同粒度，表面处理及填充量的Al(OH）3对LDPE／EVA的氧指数（OI），烟密度等级（SDR）和物理机械性能的影响。     

氢氧化铝对PE-HD／木粉复合材料阻燃性能和力学性能的影响

对Al(OH)3阻燃的高密度聚乙烯／木粉复合材料研究结果表明：随木粉和Al(OH)3添加量的增加，Al(OH)3对复合材料的阻燃效率增加，高木粉添加量的复合材料氧指数达27．1％，Al(OH)3的阻燃效率达0．203。增加木粉含量，复合材料的拉伸强度和弯曲强度明显提高；但Al(OH)3对拉伸强度的影响不大，而明显提高弯曲强度。增加木粉和Al(OH)3的含量，均能明显降低复合材料的冲击强度，破坏复合材料的韧性。     

改性Sb2O3协同十溴二苯乙烷阻燃LDPE/EVA的研究

采用熔融共混法制备了阻燃低密度聚乙烯/乙烯-醋酸乙烯共聚物(LDPE/EVA)复合材料,研究了表面有机化改性三氧化二锑(Sb2O3)与十溴二苯乙烷(DBDPE)在LDPE/EVA中的阻燃协效性,通过极限氧指数(LOI)、垂直燃烧等级(UL94)、力学性能和热稳定性等测试对复合材料进行研究。结果表明,DBDPE/Sb2O3复合阻燃剂对LDPE/EVA有良好的阻燃作用,经表面有机化改性的Sb2O3,较之未改性Sb2O3阻燃协效性增强,制品热稳定性提高,对力学性能影响较小。     

Al（OH）3和Mg（OH）2阻燃EVA性能的研究

选用形貌、粒径尺寸及分布相近的两种无机阻燃剂氢氧化铝（Al（OH）3）和氢氧化镁（Mg（OH）2），研究了二者用量对乙烯-醋酸乙烯酯共聚物（EVA）复合材料的力学性能和阻燃性能的影响，并比较了添加红磷的复合材料的力学性能和阻燃性能。研究表明：Al（OH）3和Mg（OH）2用量对复合材料性能影响比较相似，随着阻燃剂用量的增加，复合材料的阻燃性能提高，拉伸强度增加，但断裂伸长率下降；通过锥形量热仪数据看出：Al（OH），的点燃时间短，最大热释放速率和平均热释放速率低，火行为指数大，阻燃效果比Mg（OH）2好；红磷的加入对复合材料力学性能影响不大，而对阻燃性能影响较大。Mg（OH）2与红磷复配能提高复合材料的氧指数，但是，从水平和垂直燃烧角度考虑，Al（OH）3与红磷之间的阻燃协效效果更好。     

Al（OH）3在UP树脂中的阻燃性能及应用

本文根据UP树脂的燃烧机理及阻燃理论,探讨了Al(OH)_3及与红磷共同作用在UP树脂中的阻燃效能。     

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.     

Ethylene vinyl acetate copolymer nanocomposites based on (un)modified sepiolite: Flame retardancy,thermal, and mechanical properties

Flame retardant ethylene‐vinyl acetate (EVA) nanocomposites were prepared by melt blending using unmodified and modified sepiolite. Modification process of sepiolite was carried out by using 3‐aminopropyltrimethoxysilane in water/ethanol medium. Thermal, mechanical, and flame retardancy properties of the prepared nanocomposites were evaluated and compared with each other. X‐ray diffraction and scanning electron microscopy indicated that sepiolite fibers are well‐dispersed in EVA matrix. By the addition of (un)modified sepiolite, both flame retardancy and thermal stability characteristics first improved, and then deteriorated, indicating a direct relationship between these properties. It was also found that sepiolite protects carbonyl groups of EVA from further degradation. Most interestingly, a simultaneous increase in both ductility and toughness was observed in the prepared composites. Whatever the evaluated properties were, whether the mechanical, thermal, or flame retardancy, the improved properties were more remarkable when modified sepiolite was utilized. POLYM. COMPOS., 38:1302–1310, 2017. © 2015 Society of Plastics Engineers     

A novel intumescent flame retardant-functionalized montmorillonite: Preparation,characterization, and flammability properties

2,4,8,10-Tetraoxa-3,9-diphosphaspiro[5.5]-undecane-3,9-dioxide-disubstitutio-acetamide-N,N-dimethyl-N-hexadecy-ammonium bromide (PDHAB) containing phosphorus–nitrogen structure was synthesized and characterized. A novel flame retardant, montmorillonite (Mt) modified by PDHAB (PDHAB-Mt), was prepared by ion-exchange of sodium montmorillonite (Na⁺-Mt) with PDHAB. The results of X-ray diffraction (XRD) indicated that PDHAB had intercalated with Na⁺-Mt and exfoliated LDPE/EVA/20% PDHAB-Mt nanocomposites had been obtained by polymer melt intercalation which was further supported by TEM. The flammability of LDPE/EVA/PDHAB-Mt nanocomposites was investigated by the cone calorimeter test. The results showed that the addition of flame retardant PDHAB-Mt enhanced the flame retardancy of LDPE/EVA blend significantly. The results of SEM and TEM indicated that PDHAB-Mt can achieve better dispersion in the chars after combustion and the intumescent char is formed for LDPE/EVA/PDHAB-Mt nanocomposites after combustion. It is found that the char structure plays an important role for PDHAB-Mt in LDPE/EVA blend. The flame retardancy of LDPE/EVA blend was also significantly improved by an addition of PDHAB-Mt in LDPE/EVA blend.     

Dispersion and flame retardancy of ethylene vinylacetate/layered silicate nanocomposites using the masterbatch approach for cable insulating material

Ethylene vinylacetate (EVA) copolymer-based nanocomposites with maleic anhydride-grafted ethylene-vinylacetate (EVAgMA) and organically modified clay (o-clay) were prepared in a twin screw extruder by following a two-step melt compounding method. EVAgMA/o-clay masterbatches with various clay contents up to 50 wt% were examined, after which the masterbatch with the highest clay content was melt compounded with EVA for the preparation of EVA/o-clay nanocomposites containing specific amounts of clay. Further morphological dispersion of the clay particles by highly polar EVA and shearing was confirmed in the EVA/o-clay nanocomposites by X-ray diffraction (XRD) and transmission electron microscopy (TEM). These morphologies led to increased thermal properties in air as well as a considerable decrease in heat release rate (HRR). EVA/o-clay/MDH nanocomposites were also prepared using a high clay-bearing masterbatch to confirm the synergistic flame retardancy of clay as a co-additive in EVA/MDH composites. EVA/o-clay/MDH nanocomposites prepared by substituting o-clay for MDH showed significantly lower and wider HRR during combustion compared to EVA/MDH composite.     

Effect of particle size on flame retardancy of Mg(OH)2‐filled ethylene vinyl acetate copolymer composites

Four kinds of magnesium hydroxide (Mg(OH)₂) with different particle sizes are chosen and mixed with ethylene vinyl acetate copolymer (EVA) to investigate the effect of particle size on the flame retardancy of composites, which is evaluated by limiting oxygen index (LOI) testing, horizontal fire testing, and cone calorimeter. When Mg(OH)₂ filling level changes from 35 to 70 wt %, the composites filled with nano‐Mg(OH)₂ do not always possess the best flame retardancy, and among the composites filled with micro‐Mg(OH)₂, the composites filled with 800 mesh Mg(OH)₂ show the best flame retardancy; however, the composites filled with 1250 mesh presents the worst one. So the effect of particle size on the flame retardancy of micro‐Mg(OH)₂‐filled EVA is not linear as expected. All the differences are thought to result from both particle size effect and distributive dispersion level of Mg(OH)₂. To prepare the composites with better mechanical properties and flame retardancy, authors suggested that Mg(OH)₂ of smaller size should be chosen as flame retardant, and good dispersion of Mg(OH)₂ particles also should be assured. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4461–4469, 2006     

Ethylene vinyl acetate/layered silicate nanocomposites prepared by a surfactant-free method: Enhanced flame retardant and mechanical properties

Exfoliated EVA/layered silicate nanocomposites were prepared by a masterbatch process using polymer-modified layered silicate instead of small molecule surfactant-modified clays. The nanocomposites exhibited improved mechanical properties and flame retardancy. Microscale flammability test showed that the heat release capacity (HRC) and total heat release (THR) were reduced by 21-24% and 16%, respectively. Radiant gasification studies revealed that the exfoliated EVA nanocomposites exhibited better improvements in flame retardant properties of EVA than did the corresponding intercalated nanocomposites. The peak mass loss rate of the exfoliated EVA nanocomposite containing about 5 wt% clay was reduced by 80% and the mass loss rate plot was spread over a much longer period of time. The mechanical and flammability tests revealed that the observed improvements in all the desirable properties were due to the presence of both the incorporated polymeric surfactant and the nanoclay.     

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     

新型氢氧化物阻燃剂在胶粘剂领域中的应用进展

介绍了表面改性、超细化、以及与其他阻燃剂联用等途径对氢氧化物[Al(OH)3、Mg(OH)2]阻燃性能的影响,综述了新型阻燃剂在胶粘剂领域中的应用研究进展,比较了氢氧化物、改性氢氧化物、氢氧化物协同作用、氢氧化物和有机物协同作用等对各种胶粘剂阻燃性能和力学性能的改进效果,讨论了该领域研究中依然存在的一些不足,指出了今后的研究可能取得突破的几个方向。