矿物/IFR复合阻燃剂对UPR阻燃、抑烟性能的影响

将一种矿物与膨胀型阻燃剂(1FR,聚磷酸铵/季戊四醇/三聚氰胺,APP/PER/Mel)复配,应用于不饱和聚酯树脂(UPR),得到膨胀型阻燃UPR复合材料。通过氧指数(LOI)、垂直燃烧(UL94)、烟密度等级(SDR)、DSC-TG对复合阻燃材料的阻燃、抑烟及热稳定性能进行研究。结果表明,在该膨胀型复合阻燃剂中,矿物与IFR存在明显的协效作用,在矿物:APP:PER:Mel=4:2:1:1(质量比),(复合阻燃剂)=40%的情况下,LOI高达36.4%,阻燃级别为UL94V-0级,SDR为60.84,满足国家对Bl级电器类热固性塑料的使用要求。     

植酸钙/聚磷酸铵膨胀阻燃剂对增韧改性聚乳酸性能的影响

针对难以同时获得具有高阻燃性和高韧性聚乳酸(PLA)的现状,文中将聚磷酸铵和植酸钙复配形成膨胀阻燃剂加入到通过动态硫化法制备的韧性聚乳酸/不饱和聚酯共混物中(TPLA),详细研究了二者配比对TPLA阻燃性能、燃烧行为、热性能以及力学性能的影响。热重分析表明,该膨胀阻燃剂的引入并没有破坏TPLA的热稳定性,反而提高了其高温残炭量。极限氧指数(LOI)、垂直燃烧和锥形量热测试结果显示,该复配阻燃剂对TPLA表现出优异的阻燃性能,添加质量分数10%聚磷酸铵和5%植酸钙后,TPLA可以通过UL-94V-0级,LOI达到27%;与纯PLA相比,改性后TPLA的峰值热释放速率和总热释放分别下降57.5%和69.5%。力学测试结果表明,阻燃TPLA的断裂伸长率和缺口冲击强度相比聚乳酸有大幅上升,分别为聚乳酸的7.6倍和6.5倍。     

均三嗪系列膨胀型阻燃剂的合成及应用

均三嗪系列膨胀型阻燃剂具有抑烟、低毒、无腐蚀、阻燃效果佳等优点,在无卤膨胀阻燃高聚物领域具有很好的应用潜力。综述了均三嗪系列膨胀型阻燃剂的合成及应用,以三聚氰胺或三聚氯氰为基,通过化学反应重建或复配等方法可以得到一系列无卤膨胀阻燃剂,同时介绍了上述阻燃剂对高聚物的阻燃情况,最后提出了均三嗪系列阻燃剂未来的发展方向。     

黄麻纤维/聚酯纤维复合材料的阻燃改性

应用两种水性磷系阻燃剂——磷酸铵类阻燃剂(DAG-50)和磷酸酯类阻燃剂(DAG-80)及其复配阻燃剂对天然黄麻纤维进行阻燃改性,并与皮芯结构聚酯纤维制备成黄麻纤维/聚酯纤维复合材料,通过燃烧测试、SEM、红外、热失重、热失重-红外联用等技术分析了此两种阻燃剂及复配阻燃剂对黄麻纤维及其黄麻纤维/聚酯纤维复合材料的阻燃效果及阻燃机制,并筛选出适合黄麻纤维/聚酯纤维复合材料产业化的阻燃改性配方。结果表明,阻燃剂DAG-50阻燃改性效果良好,但容易析出于黄麻纤维表面。阻燃剂DAG-80能较为均匀地包覆在黄麻纤维表面,阻燃改性效果好,但其价格较高。DAG-50与DAG-80形成的复配阻燃剂,阻燃效果好,既避免了单独使用DAG-50时阻燃剂易析出问题,且复配阻燃剂接近中性,避免设备腐蚀。综合考虑成本与阻燃性能,使用DAG-50与DAG-80复配阻燃剂比例为2∶1且浓度为55wt%时,可达到黄麻纤维/聚酯纤维复合材料B1级阻燃。     

改性阻燃环氧树脂胶粘剂的研制

以三聚氰胺聚磷酸酯(MPP)为阻燃剂,以聚酯型聚氨酯预聚体改性环氧树脂E-44为基体,制备改性阻燃环氧树脂胶粘剂.通过对改性基体材料进行电子探针(EPMA)以及冲击强度测试,对改性阻燃胶粘剂进行剪切强度、热稳定性以及阻燃性能测试,从而确定了聚氨酯与阻燃剂用量对胶粘剂性能的影响.结果表明:环氧树脂100份,聚氨酯预聚体30份,阻燃剂30份,制备的改性阻燃胶粘荆具有优异的韧性和阻燃性能,其拉伸剪切强度为21.3MPa,氧指数达29.6.     

不饱和聚酯/可膨胀石墨体系的结构与阻燃性能

研究了可膨胀石墨(EG)对不饱和聚酯(UPR)的结构和阻燃性能的影响。采用氧指数、锥形量热分析、热重分析等方法进行测试和表征,用扫描电镜(SEM)观察了膨胀炭层的形貌。结果表明,使用合适粒径的EG可使UPR/EG体系的氧指数得到大幅度提高,热释放速率和质量损失速率大大降低,UPR/EG体系具有良好的阻燃性能;SEM的观察结果表明,EG形成的蠕虫状膨胀炭层紧密堆砌在材料表面,起到隔热隔氧的作用。     

阻燃化改性海泡石纤维的制备及其结构与性能

采用具有高活性端基的膨胀型阻燃剂3, 9-二氯-2, 4, 8, 10-四氯代-3, 9-二磷螺环-3, 9-二氧-[5.5] -十一烷(SPDPC)-己二胺共聚物(PSPHD)对海泡石纤维(SEP)进行阻燃化接枝改性, 并对改性海泡石纤维(PSPHD-SEP)的结构及热性能进行了SEM、 TEM、 XPS、 FTIR、 XRD、 TGA 和DTG测试。采用熔融共混制备了SEP/LDPE(低密度聚乙烯)和PSPHD-SEP/LDPE复合材料。SEM和TEM显示, 接枝前后海泡石纤维表面形貌有明显变化。XPS、 FTIR和XRD分析表明, 阻燃齐聚物PSPHD通过与SEP表面羟基反应对其进行阻燃接枝改性, 这对SEP纤维的结构有一定影响, 但并未造成结构的根本破坏。TGA和DTG测试分析表明, 阻燃接枝改性改变了海泡石纤维的热分解历程, 证明在海泡石表面确实发生了接枝反应。当PSPHD-SEP的质量分数为5%时, PSPHD-SEP/LDPE复合材料的极限氧指数值(LOI)可达23。      

芳基二磷酸酯的合成、表征及对ABS的阻燃研究

为了获得无卤阻燃ABS产品,选用了磷酸酯类阻燃剂和成炭剂复配的方式对ABS进行了阻燃研究.合成了两种阻燃剂:四-(2,6-二甲苯基)间苯二酚二磷酸酯(DMP-RDP)、四-(2,6-二甲苯基)对苯三酚二磷酸酯(DMP-HDP),采用FTIR、1H-NMR、TGA等对产物进行了表征.将两种含磷阻燃剂分别和酚醛树脂复配对ABS进行阻燃处理,并研究其热降解行为.氧指数(LOI)测试显示,两种含磷阻燃剂和酚醛树脂复配比例为4:1时,LOI最大,且DMP-HDP的氧指数稍高.结合TGA分析,阻燃剂复配可以促进成炭,磷残留于炭层中,有利于阻燃,炭残余量越大,炭层越稳定,阻燃效果越好.     

MMT/UPR包覆材料分散工艺研究

采用XRD和TEM两种测试手段,研究了分散工艺、分散时间、固化温度对纳米层状硅酸盐(MMT)片层在不饱和聚酯(UPR)包覆剂中剥离行为的影响。研究发现,将有机MMT与UPR在50℃下预混,静置1h后,在50℃下经高剪切分散处理UPR分子链对MMT片层的插层效果最好;延长分散作用时间,MMT片层的插层能力得到加强,从而可以将更多的UPR分子链插层进入MMT片层中;升高固化温度,MMT片层在UPR中的获得较好的剥离。     

阻燃型不饱和聚酯树脂的制备及其与不同阻燃剂的优化协同

为了进一步发展、推广不饱和聚酯树脂的应用,采用一步和两步合成工艺法合成了一种少烟、低毒通用型不饱和聚酯树脂(UPR),并向其中添加3种阻燃剂制成了一种阻燃型聚酯树脂.采用现代技术分析了2种合成品的酸值、红外光谱(FT-IR),同时也进行了差示扫描量热分析(DSC).结果表明:两步法合成工艺更佳;在UPR中加入不同类型及配比的阻燃剂,能得到阻燃型不饱和聚酯树脂;当UPR与聚磷酸铵(APP)、季戊四醇(PER)、三聚氰胺(MEL)阻燃剂之比为60∶10∶5∶5时,3种阻燃剂的协同作用最佳,以MEL取代PER,即UPR∶ APP∶PER∶MEL是60∶15∶0∶5,也能达到相近的效果.     

Innovative green nanocomposites based on silicate clays/lignin/natural fibres

A new type of nanocomposite based on silicate clays, lignin and natural fibres has been elaborated by shear mixing in a twin-screw extruder. Either sepiolite or organically modified montmorillonite (Org-MMT) have been chosen for being dispersed into lignin/natural fibres system. The morphological aspect of the obtained nanocomposites has been controlled by Transmission Electronic Microscopy (TEM). For sepiolite-based nanocomposites, individual needles have been observed while Org-MMT-based nanocomposites have exhibited partial delamination of silicate layers into intercalated and exfoliated nanostructures. The properties of the specimens have been studied by thermogravimetry (TGA), Dynamic Mechanical Analysis (DMA) and flexural tests. Incorporation of 2% or 5% w/w of sepiolite does not influence the mechanical and thermal behaviour compared to the reference lignin/natural fibres composite while Org-MMT-based nanocomposites have shown improved properties.     

Preparation,structure and thermal properties of polylactide/sepiolite nanocomposites with and without organic modifiers

Polylactide-based nanocomposites containing unmodified and organic modified sepiolite were prepared through a solution casting method. The structure and properties of materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). From the results it can be concluded that the bundles of sepiolite have been dispersed into small aggregates containing several nanorods without destroying the crystal structure. Sepiolite nanofibers were well dispersed in the PLA matrix, exhibiting a randomly orientation with the contact among them in all cases. But the thermal stability of nanocomposites has been improved more by introducing unmodified sepiolite than that with organic modified sepiolite, which has also been confirmed by molecular dynamics simulation results that hydrophobic parts of organic modifiers could prevent the interaction between PLA molecules and sepiolite surface.     

Effects of sepiolite clay on degradation and fire behaviour of a bisphenol A-based epoxy

As-received and pre-treated sepiolite/epoxy systems, characterised by an inorganic content from 2 to 10 wt.%, were investigated in order to assess induced-filler effect on degradation and fire behaviour.Thermogravimetrical results show that the thermal stability of the hosting epoxy, is slightly affected by the presence of sepiolite for both typologies; whereas, changes induced in char morphology by the pre-treated clay will significantly affect the fire behaviour of the final nanocomposite.Modelling of thermo-gravimetrical results in air atmosphere, by means of Kissinger procedure, shows a noteworthy reduction of activation energies associated with each degradation steps, especially at highest sepiolite content either by using as-received and pre-treated inorganic filler. This substantially indicates that the presence of sepiolite shorten the whole degradation process on the temperature scale. On the other hand, the different morphology of the char layer during the burning process can have relevant flame retardant effects acting on both condensate and vapour phase. Analysing the cone calorimetric data, a reduction of about 27% of the peak of heat release rate for the highest sepiolite percentage is measured and the burning total period is increased thus confirming that sepiolite when pre-treated represents a valid fire retardant inorganic filler for such a system.     

Polyimide/sepiolite nanocomposite films: Preparation, morphology and properties

Polyimide/sepiolite nanocomposite films have been prepared via an in situ polymerization method. The process involves the dispersion of sepioite in N,N-dimethylacetamide, polycondensation of 2,2′-bis [4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride and 4,4′-oxydianiline in the presence of sepiolite suspension to form poly(amic acid), and the thermal imidization of poly(amic acid)/sepiolite nanocomposite. The morphology, thermal and mechanical performance, and water absorption of nanocomposite films were systematically studied with various sepiolite contents. The results indicated that sepiolite was dispersed homogeneously at a nanometer scale in polyimide matrix. Owing to such nanodispersion of sepiolite, the polyimide/sepiolite nanocomposite films exhibit dramatic improvements on the mechanical properties and the coefficient of thermal expansion while fine thermal stability and low water absorption capacity were also maintained. When the sepiolite content increased to 16% the polyimide/sepiolite nanocomposite film achieved as much as 41% and 94% increase on the tensile strength and modulus respectively, and 50% decreased in coefficient of thermal expansion.     

Multiwalled carbon nanotubes and sepiolite nanoclays as flame retardants for polylactide and its natural fibre reinforced composites

This work aims to develop a fully bio-based polylactic acid (PLA) composite with improved flame retardancy, utilising the unique properties of sepiolite nanoclay (Sep) and multiwalled nanotubes (MWNT). The pyrolysis combustion flow calorimeter (PCFC) also known as the microcalorimeter was used to screen the various PLA nanocomposites with respect to their potential flammability performance. The heat release capacity (HRC) which is an indicator of a materials fire hazard, reduced by 58% for the PLA ternary system based on sepiolite and MWNTs. Thermal gravimetric analysis (TGA) showed significant improvements to the residual char towards the later stages of the thermal ramp. The PLA ternary nanocomposite showed a 45% reduction in peak heat release (PHRR) when tested in the cone calorimeter. A further noteworthy observation was the 25% reduction in PHRR upon the introduction of hemp fibre into the PLA nanocomposite system.     

Adsorption of cationic polyacrylamide onto sepiolite

The adsorption of PAM onto sepiolite from aqueous solutions has been investigated systematically as a function of some parameters such as calcination temperature of sepiolite, pH, ionic strength and temperature. The adsorption of cationic polyacrylamide (PAM) increases with pH from 5.50 to 11.00, temperature from 25 to 55 degrees C and ionic strength from 0 to 0.1molL(-1). The sepiolite sample calcined at 200 degrees C has a higher adsorption capacity than the other calcined samples. Adsorption isotherms of PAM onto sepiolite have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The physical properties of this adsorbent are consistent with the parameters obtained from the isotherm equations. The zeta potentials of sepiolite suspensions have been measured in aqueous solutions of NaCl and different PAM concentrations and pH. From the experimental results: (i) pH strongly alters the zeta potential of sepiolite, (ii) sepiolite has an isoelectric point at about pH 6.6 in water and about pH 8 in 250mgL(-1) PAM concentration, (iii) PAM changes the interface charge from negative to positive for sepiolite. Effect of temperature on adsorption has been quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy. The dimensionless separation factor (R(L)) has shown that sepiolite can be used for adsorption of PAM from aqueous solutions.     

聚丙烯/海泡石纳米复合材料的制备与研究

采用CTAB对海泡石进行化学修饰,制备了改性海泡石,将海泡石、改性海泡石分别与聚丙烯(PP)熔融共混制备了熔融插层纳米复合材料.用XRD、DSC、SEM等测试手段对复合材料的结构进行表征,同时对复合材料的力学性能进行测试.结果表明,经过改性的海泡石亲油性增强;XRD结果表明PP大分子已经进入海泡石层间,形成插层型复合材料;DSC结果表明,一定量的改性海泡石的加入起到了异相成核作用,使复合材料的结晶更加完善;力学性能表明,改性海泡石使材料的冲击强度提高;SEM显示,改性海泡石呈两维纳米级均匀分散在PP基体中且与基体的界面结合良好.     

PP-g-MAH对PP/OMMT纳米复合材料阻燃性能的影响

采用聚丙烯接枝马来酸酐(PP-g-MAH)作为相容剂,通过熔融插层法制备了具有阻燃性能的聚丙烯/有机蒙脱土(PP/OMMT)纳米复合材料。考察了相容剂、蒙脱土的用量等对纳米复合材料的阻燃性能的影响,并用X射线衍射(XRD)、透射电镜(TEM)和热重分析(TG)等对材料进行了表征。TEM照片和XRD结果,表明PP-g-MAH能够很好地改善OMMT与PP的相容性,OMMT能在基体中达到剥离。当OMMT和PP-g-MAH质量分数分别为5%和10%时,热释放速率峰值(PHRR)和平均热释放速率(MHRR)分别为491 kW/m2和286 kW/m2,比纯PP降低了42%和30%,TG分析表明PP/PP-g-MAH/OMMT纳米复合材料具有了更高的热稳定性。     

Use of nanoclay as an environmentally friendly flame retardant synergist in polyamide-6

Due to their very high levels of flame retardancy, chlorinated and brominated flame retardants had been the most widely used flame retardant additives in plastics industry. However, these flame retardants lead to formation of very toxic volatiles and by-products during fire. Therefore, the recent trend is to replace all of them with non-halogenated flame retardants. In this respect, the use of nanoclays as a synergist flame retardant is becoming more and more important. Thus, the main aim of this work was to investigate the synergistic flame retardant effect of nanoclays with phosphorous compounds in polyamide-6 composites. For this purpose, exfoliated clay nanocomposites of flame retarded/glass fiber reinforced polyamide-6 were prepared by melt compounding. A flame retardant based on phosphorus compounds was used at various levels in glass fiber reinforced polyamide-6 and nanocomposites. Flammability and fire behaviors were evaluated by limiting oxygen index, UL94 and cone calorimeter tests. Substitution of a certain fraction of the flame retardant with nanoclays was found to significantly reduce the peak heat release rate and delay the ignition in cone calorimeter. Moreover, remarkable improvements were obtained in limiting oxygen index along with maintained UL94 ratings.