蒙脱土插层尼龙66及其合金力学性能研究

先采用有机化蒙脱土(org MMT)插层尼龙66制得了PA66/PP纳米复合材料,对其力学性能进行了测试。试验结果表明:MMT含量为7%时,PA66/MMT的各项性能达到最优,但是材料的韧性仍较差,进而采用与聚丙烯共混改性的方法增韧制得PA66/PP/MMT纳米复合材料,当MMT含量为5%,PA66∶PP为80∶20时,材料的冲击强度提高45 4%,而其他各项性能基本保持不变。     

几种插层剂改性的MMT／PA66纳米材料的性能

用多种插层剂合成了有机改性蒙脱土（MMT），将PA66与改性MMT共混制成纳米材料，表征了其结构和力学性能。5％的纳米MMT1631能将PA66的冲击强度提高近50％，3％的MMT1827能将PA66的断裂伸长率提高52．5％，观察到MMT／PA66纳米塑料的无熔滴等阻燃特性，总结了不断插层剂改性MMT／PA66纳米材料的特点，发现MMT与常规阻燃剂之间有力学协效作用和阻燃协效作用，能提高PA66的力学性能和阻燃性能。     

固相剪切碾磨制备PA6/蒙脱土纳米复合材料

采用固相剪切碾磨方法制备尼龙6/蒙脱土(PA6/MMT)纳米复合材料。表征了复合材料的结构,研究了其力学性能、热稳定性能及结晶性能。结果表明,PA6/MMT纳米复合材料的力学性能较PA6有较大提高,含4%MMT的PA6/MMT纳米复合材料的拉伸弹性模量从2697 MPa提高到3299 MPa,拉伸强度从63.6 MPa提高到77.8MPa;起始分解温度和最大失重温度均高于纯PA6;PA6/MMT纳米复合材料中PA6的结晶温度和结晶速率提高。     

剥离型(苯乙烯/马来酸酐)共聚物/蒙脱土纳米复合材料的制备

研究了制备剥离型(苯乙烯/马来酸酐)共聚物(SMAH)蒙/脱土(MMT)纳米复合材料的方法。研究表明,通过原位插层及熔融插层只能制备出插层型的SMAH/MMT纳米复合材料。为了制备剥离型的SMAH/MMT纳米复合材料,先将尼龙6(PA6)与MMT熔融插层制备出PA6/MMT纳米复合材料,再用抽提的方法将PA6/MMT复合材料中的部分PA6除去,得到含有少量PA6的剥离型MMT,然后将剥离型MMT与SMAH共混,从而制备出剥离型的SMAH/MMT纳米复合材料。该复合材料的粘度低于SMAH,且具有较好的加工性能。     

原位聚合制备尼龙610/改性蒙脱土纳米复合材料的研究

采用增塑剂N-甲基苯磺酰胺对蒙脱土(MMT)进行改性,通过原位聚合法制备了尼龙(PA)610/改性MMT纳米复合材料。研究了改性MMT用量对PA610/改性MMT纳米复合材料性能的影响。结果表明,当改性MMT的质量分数为4%时,纳米复合材料的冲击强度和拉伸强度达到最大值,断裂伸长率则随着改性MMT用量的增加而降低。扫描电子显微镜观察发现,改性MMT均匀分散在PA610基体中。     

PA66/蒙脱土纳米复合纤维性能的研究

对PA66/蒙脱土 (MMT)纳米复合材料进行了纺丝及拉伸试验 ,并对该纤维的力学性能、热性能进行了研究。结果表明 ,制得的PA66/MMT纳米复合材料纤维的模量有一定的提高 ,干热收缩性也有所改善 ,但纤维的断裂强度有所下降。     

PA6/PSAM/MMT纳米复合材料制备与性能研究

将聚(苯乙烯-丙烯酰胺)季铵盐(PSAM)修饰蒙脱土(MMT)与尼龙(PA)6熔融共混,制备了PA6/PSAM/MMT纳米复合材料。考察了在MMT含量相同的情况下不同丙烯酰胺含量的PSAM修饰MMT对纳米复合材料力学性能的影响,并通过热重分析、X射线衍射等方法对此种纳米复合材料进行了表征。结果表明,当PSAM中丙烯酰胺的质量分数为10%时,PA6/PSAM/MMT纳米复合材料的综合性能较好。     

酚醛树脂改性纳米蒙脱土填充PA6的制备及性能研究

分别利用经十八烷基三甲基氯化铵(OTAC)、酚醛树脂(PF)表面改性的纳米蒙脱土(MMT)填充聚酰胺(PA)6,研究了不同表面改性剂及其用量对PA6的力学性能、热性能和吸水性的影响。结果表明,经OTAC改性的纳米MMT和经PF改性的纳米MMT对PA6的热性能改善效果有限,但有利于提高PA6的刚性和降低吸水性。PF改性纳米MMT对PA6的改性效果优于OTAC改性纳米MMT,当PF改性纳米MMT的质量分数为3%时,材料的拉伸强度、弯曲强度和维卡软化温度分别比纯PA6提高了12.3%、58.8%和2%,吸水率降低0.5%。     

聚酰胺6/环氧树脂改性蒙脱土纳米复合材料的制备与性能

采用环氧树脂改性蒙脱土（MMT）得到有机化蒙脱土（OMMT）,再用熔融插层法制备了聚酰胺6 （PA6）/ OMMT纳米复合材料。采用X射线衍射仪、透射电子显微镜、万能材料试验机、热重分析仪等研究了PA6/OMMT复合材料的形态结构、力学性能和热稳定性。结果表明,经环氧树脂改性得到的OMMT的层间距明显增加,从未改性的1.22 nm增加到5.13 nm,并以纳米尺度分散于PA6基体中;随着OMMT含量的增加,PA6/ OMMT复合材料的强度和模量增加,热变形温度提高,其拉伸强度可达76 MPa,弯曲模量达到3.462 GPa,热变形温度为134 ℃;PA6/ OMMT复合材料失重10 %时的温度为422 ℃,比纯PA6的406 ℃提高了16 ℃,改善了PA6的热稳定性。     

原位聚合制备尼龙6/改性氢氧化镁纳米复合材料及其性能的研究

对纳米氢氧化镁(NMH)进行硅烷KH570接枝改性后,将甲基丙烯酸甲酯(MMA)与之共聚获得表面改性的纳米氢氧化镁(MNMH),然后在催化剂作用下原位聚合制备PA 6/MNMH纳米复合材料。利用FTIR、SEM、热重分析和电子拉力机对NMH及PA 6/MNMH纳米复合材料的结构与性能进行测试与表征。红外光谱分析表明改性的NMH表面成功接枝了KH570和聚甲基丙烯酸甲酯(PMMA)。PA 6/NMH-KH570-PMMA复合材料的缺口冲击强度比PA 6/NMH纳米复合材料的提高34%。NMH或其改性NMH的加入提高了PA 6纳米复合材料的热稳定性。     

插层剂对蒙脱土/PA6纳米塑料性能的影响

用4种插层剂合成了有机改性蒙脱土（MMT），将PA6与改性MMT熔融共混制成纳米塑料，用IR、XRD和透射电镜表征了结构，观察到MMT／PA6纳米塑料的无熔滴等阻燃特性。通过改性纳米塑料力学性能的研究表明：质量分数为6％的MMT能提高PA6的LOI值，MMT1831质量分数为3％时弯曲模提高57．1％，MMT1831质量分数为5％时弯曲强度提高42．4％；MMT与常规阻燃剂之间有力学协效作用和阻燃协效作用，能同时提高PA6的力学性能和阻燃性能。     

Chemical effects of cationic surfactant and anionic surfactant used in organically modified montmorillonites on degradation and fire retardancy of polyamide 12 nanocomposites

Three kinds of organically modified Na⁺-montmorillonites (OMMTs), including two kinds of octadecylammonium modified montmorillonite with different contents of octadecylammonium and a kind of sodium dodecylsulfonate (SDSo) modified montmorillonite, were used to prepare polyamide 12 (PA12)/OMMT nanocomposites. Effects of the modifiers on degradation and fire retardancy of PA12/OMMT nanocomposites were investigated. Acid sites formed in cationic surfactant modified MMT via Hoffman decomposition could accelerate degradation of PA12 at high temperature. However, catalytic effect of the acid sites on carbonization of the degradation products promoted char barrier formation, which reduced heat release rate (HRR). Higher content of cationic surfactant in OMMT is beneficial to fire retardancy of PA12 nanocomposites and the dispersion states of OMMT have assistant effects. In contrast, Na⁺-montmorillonite (Na-MMT) and anionic surfactant modified MMT (a-MMT) could not form acid sites on the MMT layers; in this case, fire retardancy of PA12/Na-MMT appears to have no improvement and PA12/a-MMT appears to have limited improvement.     

Enhanced mechanical properties and fire retardancy of polyamide 6 nanocomposites based on interdigitated crystalline montmorillonite–melamine cyanurate

Polyamide 6 (PA6)–montmorillonite (MMT)–melamine cyanurate (MCA) nanocomposites were prepared by the incorporation of interdigitated crystalline MMT–MCA. Their morphologies were assessed by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal stability measurement by thermogravimetric analysis, mechanical properties measurement by tensile tests, and fire retardancy measurement by limiting oxygen index testing and vertical burning testing (UL‐94). The results indicate that MMT–MCA was homogeneously nanodispersed in PA6. Compared with PA6–MCA, the PA6–MMT–MCA nanocomposites showed enhanced thermal stability. The mechanical properties and fire retardancy show that the PA6–MMT–MCA nanocomposites with 5 wt % total loading of MMT–MCA reached UL‐94 V‐2 rating (3.2 mm) and significantly increased the tensile strength of PA6 up to 24.8 % with only 1 wt % MMT in PA6. Through the control the weight ratio of MMT and MCA in MMT–MCA, the Young's modulus of PA6 could be adjusted in a very wide range (300–1100 MPa) because of the dual role of the rigid MMT and nonrigid MCA layers. The reinforced mechanism of the mechanical properties was also investigated. Consequently, the PA6–MMT–MCA nanocomposites with a good nanodispersing ability, improved thermal stability, excellent mechanical properties, and good flame retardancy were obtained and could provide broad prospects for wider applications for PA6 materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46039.     

Thermal stability and crystalline of electrospun polyamide 6/organo‐montmorillonite nanofibers

This research is mainly to investigate the thermal and crystalline differences between polyamide 6/montmorillonite (PA6/MMT) and polyamide 6/organo‐montmorillonite (PA6/O‐MMT) nanofibers, which were both prepared by electrospinning under the same process conditions. The structures of PA6/MMT and PA6/O‐MMT nanofibers were observed by scanning electrical microscope. It was identified that the interval between O‐MMT clays was increased in the PA6 matrix compared to that of MMT, which was detected by X‐ray diffraction (XRD). The thermal properties of PA6 nanofibers contained O‐MMT particles were more efficient than PA6/MMT nanofibers, that was verified using thermal gravimetric analysis. The crystalline properties of the electrospun nanofibers was investigated using differential scanning calorimeter and it was found that the degree of crystallinity in the PA6 nanofibers loaded with O‐MMT was much higher than PA6/MMT and PA6 nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Using PA6 as a charring agent in intumescent polypropylene formulations based on carboxylated polypropylene compatibilizer and nano‐montmorillonite synergistic agent

The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M = 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA‐6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6‐g‐EPP cocrystallized with PA6, and EPP‐g‐PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano‐montmorillonite (nano‐MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano‐MMT enhanced the mechanical strength by 44.3%. SEM showed that nano‐MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano‐MMT was an effective flame retardant in improving combustion properties of polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 739–746, 2006     

PA6/MMT/SGF复合材料的流变性能

利用毛细管流变仪和动态流变仪分别测试了纯尼龙(PA)6以及PA6/蒙脱土(MMT)和PA6/MMT/短玻璃纤维(SGF)复合材料的剪切粘度、复数粘度、储能模量和损耗模量,并用Han曲线分析了材料的粘弹特性.结果表明,在低剪切速率下,PA6/MMT和PA6/MMT/SGF复合材料的剪切粘度大于纯PA6的剪切粘度;在高剪切速率下,PA6/MMT和PA6/MMT/SGF复合材料剪切粘度低于纯PA6的剪切粘度.动态流变测试显示,PA6/MMT/SGF复合材料在低频区呈类固响应,其储能模量和复数粘度明显提高.Han曲线表明,PA6/MMT/SGF复合材料的粘性响应占主导地位.     

PET/PA6/蒙脱土体系的可纺性和染色性能研究

分别使用一步和二步熔融插层法,通过双螺杆挤出机制备了PET/PA6/蒙脱土(MMT)纳米复合材料。利用X-射线衍射、扫描电镜研究了蒙脱土在PET/PA6中的插层情况及PET、PA6的相容性,发现两种方法均可以使MMT在基体中达到纳米级分散,得到剥离型的纳米复合材料。对PET/PA6/MMT共混体系的可纺性及染色性作了比较。结果表明:PET/PA6/MMT组成为90/10/2的一次共混体系具有较好的可纺性,并具有良好的分散染料可染性。     

Dually reinforced all‐polyamide laminate composites via microencapsulation strategy

A new two‐stage strategy is disclosed for the preparation of all‐polyamide laminate composites based on polyamide 6 (PA6) matrices reinforced by high volume fractions of polyamide 66 (PA66) textile structures and three different types of nanoclays. In the first stage, PA6 microcapsules (MC) loaded with montmorillonite nanoclays (MMT) are synthesized by activated anionic ring‐opening polymerization of ε‐caprolactam in solution in the presence of three different organically treated MMT brands. In the second stage, the MMT‐loaded MC obtained with controlled molecular weight, composition and granulometry are compression molded in the presence of PA66 textile structures to produce the final dually reinforced laminate composites. Mechanical tests in tension, flexion, and impact for selected composites in this study showed up to 73% increase of the Young's modulus, up to 142% increase of the stress at break, and more than a fivefold increase of the notched impact resistance. The mechanical behavior of the dually reinforced composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy, and the matrix crystalline structure as revealed by DSC and microfocus synchrotron X‐ray diffraction. POLYM. ENG. SCI., 57:806–820, 2017. © 2016 Society of Plastics Engineers     

Thermal stability and flammability of polyamide 66/montmorillonite nanocomposites

Exfoliated nanocomposites based on polyamide 66 (PA66) and montmorillonite (MMT) were prepared and their thermal stability and combustion behaviour were investigated by using thermal gravity analysis and cone calorimeter. The nanocomposites exhibit higher thermal stability and good flame retardancy. The catalytic decomposition effect of MMT and the barrier effect of layer silicates are presented directly in isothermal oxidation experiment. The initial heat release rate plots show that the addition of MMT can accelerate the ignition of PA66 matrix. A ceramic-like char forms in the surface of the nanocomposites during burning. It is characterized by attenuated total reflection infrared spectra and scanning electron microscopy.