聚氨酯/蒙脱土纳米复合材

聚氨酯／蒙脱土(PU／MMT)纳米复合材料主要是采用插层聚合法合成的1种综合性能优越的新型材料。广角X-射线(WAXD)和透射电镜(TEM)分析结果表明蒙脱土以3～4nm的层间距分散在聚氨酯基体中，因此获得非常有序的插层结构。当PU中加入质量分数为8％的有机蒙脱土(OMMT)时，其拉伸强度提高1．5倍以上，伸长率则提高1．2倍以上；其吸水性随着有机蒙脱土含量的增加而下降，并具有较好的阻隔性。同时热失重分析(TGA)表明，PU／MMT纳米复合材料的热稳定性略有提高。因此，PU／MMT纳米复合材料具有广泛的工业应用前景。     

不同方法制备聚氨酯/蒙脱土纳米复合材料的力学性能研究

采用3种不同制备方法获得了聚氢酯／蒙脱土（PU／MMT）纳米复合材料。通过对材料力学性能测试,发现制备方法对纳米复合材料的拉伸强度杀Ⅱ断裂伸长率有明显影响。蒙脱土和三羟基聚氧化丙烯醚（GP03）预研磨混合制备法所得的纳米复合材料呈现出较好的力学性能。当有机蒙脱土质量分数为2％时,其拉伸强度和断裂伸长率分别比纯聚氨酯材料提高丁30％-68％。     

有机插层剂对聚酰胺6／MMT纳米复合材料制备的影响研究

以烷基胺、季铵盐和氨基酸作为有机插层剂与蒙脱土片层进行阳离子交换，制备出层间距不同的有机蒙脱土。采用熔融插层法和原位聚合法分别制备聚酰胺（R％）／蒙脱土（MMT）纳米复合材料，并利用XRD、FT-IR、TEM对有机蒙脱土及纳米复合材料进行结构表征。研究结果表明：用烷基胺、季铵盐和氨基酸有机插层剂改性的蒙脱土层间距由原来的1．25nm分别增大到3．21nm、3．99nm和1．82m；季铵盐有机插层剂更适用于熔融插层法制备PA6／MMT纳米复合材料，而氨基酸有机插层剂更适用于原位聚合法制备PA6／MMT纳米复合材料。     

高密度聚乙烯／蒙脱土纳米复合材料的制备与性能研究

采用马来酸酐接枝乙烯醋酸乙烯酯（EVA-g-MAH）和马来酸酐接枝低密度聚乙烯（PE-LD-g-MAH）为相容剂，制备了高密度聚乙烯傣脱土（PE-HD／MMT）纳米复合材料。用X射线衍射和扫描电镜对有机蒙脱土和PE-HD／MMT复合材料的结构进行了表征，研究了蒙脱土和相容剂含量对制备的纳米复合材料力学性能及热性能的影响。结果表明，相容剂的加入有利于插层。MMT在复合材料中呈纳米级分散。其层间距可由2．10nm增大至3．85nm。MMT含量为3％（质量分数，下同）、EVA-g-MAH含量为15％时，复合材料的综合力学性能最好，冲击强度和拉伸强度分别较PE-HD提高43．7％和5.8％。     

PU/OMMT纳米复合材料的制备与性能研究

采用单体插层聚合方法制备聚氨酯（PU）／有机蒙脱土（OMMT）纳米复合材料,并对其结构和性能进行分析。结果表明，经双羟乙基十二烷基三甲基氯化铵改性得到的OMMT（DK2）层间距较大；DK2质量分数为0．03时,PU／OMMT纳米复合材料中OMMT剥离程度较大，PU的插层效果较好,复合材料的物理性能和热稳定性能优良。     

纳米蒙脱土-脂肪族聚氨酯弹性体的合成与制备

采用聚四氢呋喃醚（PTMG1000）为软段,4,4’-二环己基甲烷二异氰酸酯（HMD1）、异佛尔酮二异氰酸酯（1PD1）为硬段,层间距分别为1．95nm和2．40nm的2种有机蒙脱土,以插层聚合法制备出不同硬段含量和有机蒙脱土含量的纳米蒙脱土．脂肪族聚氨酯弹性体,并研究了硬段含量、有机蒙脱土含量、二异氰酸酯和有机蒙脱土种类对脂肪族聚氨酯弹性体力学性能的影响。结果表明,硬段含量对材料力学性能影响最大,其次是有机蒙脱土含量。当硬段质量分数达40％时,拉伸强度最高达14．06MPa;有机蒙脱土少量加入可有效提高材料的撕裂强度和断裂伸长率。以HMD1、PTMG1000和MMT2为原料,硬段质量分数为40％时,所合成的纳米蒙脱土-脂肪族聚氨酯弹性体具有较好的力学性能。     

蒙脱土插层对聚氨酯复合材料的结构和性能影响

用聚氧化丙烯醚二元醇插层有机蒙脱土，再与二异氰酸酯、扩链剂进行原位聚合反应，制备了聚氨酯插层纳米蒙脱土复合材料。该复合材料经X衍射、红外光谱和热分析测定．证明了复合物中的蒙脱土已被基本剥离，并形成了蒙脱土与聚氨酯硬段结合的微相有序结晶结构。复合材料的力学性能测试结果说明，当质量分数为1％的有机蒙脱土加入聚氨酯后，拉伸强度和拉断伸长率分别是未用蒙脱土的1．7倍和1．8倍。     

SMA/MMT纳米复合材料的制备

采用原位插层法制备了苯乙烯-马来酸酐共聚物／蒙脱土（SMA／MMT）纳米复合材料,采用X射线衍射研究了苯乙烯与马来酸酐的配比、蒙脱土用量、引发剂浓度、溶剂类型、聚合温度等因素对插层效果的影响。结果表明,当MMT的用量为3％（质量分数＋下同）时,可制得剥离型的SMA／MMT纳米复合材料;当苯乙烯与马来酸酐的质量比为1：1,MMT用量为15％、引发剂用量为1％、以丁酮为溶剂、聚合温度为90℃时,可制备出部分剥离型的SMA／MMT纳米复合材料。     

聚氨酯丙烯酸酯/蒙脱土纳米复合材料的制备与研究

采用烯丙基三苯基氯化磷对蒙脱土(MMT)进行有机化处理,并采用熔融插层法制备了聚氨酯丙烯酸酯(PUA)/MMT纳米复合材料,探讨了改性MMT用量对PUA/MMT纳米复合材料性能的影响。结果表明,改性MMT的加入可提高复合材料的耐热性与断裂伸长率,当改性MMT的质量分数为3%时复合材料的综合性能最佳,其起始分解温度和断裂伸长率分别达到了321.8℃和96.03%。     

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。     

Mechanical properties of polyurethane/montmorillonite nanocomposite prepared by melt mixing

Nanocomposites from polyurethane (PU) and montmorillonite (MMT) were prepared under melt‐mixing condition, by a twin screw extruder along with a compatibilizer to enhance dispersion of MMT. MMT used in this study was Cloisite 25A (modified with dimethyl hydrogenated tallow 2‐ethylhexyl ammonium) or Cloisite 30B (modified with methyl tallow bis‐2‐hydroxyethyl ammonium). Maleic anhydride grafted polypropylene (MAPP) was used as the compatibilizer. XRD and TEM analysis demonstrated that melt mixing by a twin‐screw extruder was effective in dispersing MMT through the PU matrix. The PU/Cloisite 30B composite exhibited better interlayer separation than the PU/Cloiste 25A composite. Nanoparticle dispersion was the best at 1 wt % of MMT and improved with compatibilizer content for both composites. Properties of the composites such as complex viscosity and storage modulus were higher than that of a pure PU matrix and increased with the increase in MMT content, but decreased with the increase in compatibilizer content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The effects of soft‐segment molecular weight and organic modifier on properties of organic‐modified MMT‐PU nanocomposites

The effects of soft‐segment molecular weight and organic modification of montmorillonite (MMT) on thermal and mechanical properties of segmented polyurethane (PU) elastomers were investigated. The PU/MMT nanocomposites were prepared by in situ polymerization, and the compositions included soft segments with number average molecular weights of 1000, 2000, and 2900, and organic‐modified MMT (including MMT‐30B and MMT‐I30E). The nanocomposites produced were characterized using wide‐angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and mechanical testing. The TEM and XRD results revealed that both MMT‐30B and MMT‐I30E were intercalated, and partially exfoliated by the PU. Mechanical tests showed that the PU1000 series in soft‐segment molecular weight yielded superior tensile properties compared with the PU2000 and PU2900 series. Also, for a given molecular weight of soft segment in PU, the MMT‐30B nanocomposites exhibited greater increases in Young's modulus, tensile strength, and elongation at break than the MMT‐I30E counterpart, and the crystallinity of PU was enhanced by the clays. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface‐modifiers of clay on mechanical properties of rigid polyurethane foams/organoclay nanocomposites

Three different surface modifiers, octadecyl trimethyl ammonium (ODTMA), octadecyl primary ammonium (ODPA), and decanediamine (DDA) were used to modify Na⁺? montmorillonite (MMT), and the resultant organoclays were coded as ODTMA‐MMT, ODPA‐MMT, DDA‐MMT, respectively. Rigid PU foams/organoclay composites were prepared by directly using organoclay as the blowing agent without the addition of water. Investigation shows that the morphology of the nanocomposites is greatly dependent on the surface modifiers of clay used in the composites. In detail, DDA‐MMT is partially exfoliated in the PU matrix with the smallest cell size, while two others are intercalated in the PU matrices with smaller cell sizes. The sequence of their cell sizes is pristine PU foams > rigid PU foams/ODTMA‐MMT > rigid PU foams/ODPA‐MMT > rigid PU foams/DDA‐MMT, and the average cell size of rigid PU foams/DDA‐MMT composites decreases evidently from 0.30 to 0.07 mm. Moreover, all rigid PU foams/organoclay composites show remarkable enhanced compressive and tensile strengths as well as dynamic properties than those of PU foams, and the enhancement degree coincides well with the relative extent of internal hydrogen bonding of materials and gallery spacing of organoclay. For example, in the case of rigid PU foams/DDA‐MMT composite, 214% increase in compressive strength and 148% increase in tensile strength compared with those of pure PU foams were observed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The synthesis and characterization of polyurethane/clay nanocomposites

The water absorption of montmorillonite was studied using TGA and FTIR, and a removal method through boiling with toluene was investigated. PU/MMT was synthesized and its morphology, thermal dynamic mechanical properties and tensile behaviour were investigated by WAXD, FTIR, DMTA and Instron techniques. We find that, compared with the PU matrix, the intercalated PU/MMT nanocomposite was reinforced and toughened by the addition of nanometer‐size MMT layers. Copyright © 2003 Society of Chemical Industry     

Structure and Property of PU/MMT Nanocomposites by In-Situ Polymerization

A montmorillonite modified by octadecylammonium salt (OMMT) was prepared. A polyurethane (PU)/montmorillonite nanocomposite was synthesized by in-situ polymerization using the OMMT, poly(propylene glycol), 4,4-diphenylmethylate diisocyanate, and 1,4-butanediol. The MMT platelets were dispersed in PU matrix on a 10 ～ 50 nm scale. Compared to that of pure PU, the tensile strength and tear strength of the PU/OMMT nanocomposites increased, respectively, and the MMT platelets dispersed on a nanometer scale enhanced the PU. The temperature of initial weight loss of the PU/OMMT nanocomposites was lower than that of pure PU because of the acid catalytic action of protonated MMT platelets in the first thermodegradation step. But its temperature of initial weight loss was higher than that of pure PU because of the barrier effect of the MMT platelets in the second thermodegradation step.     

Nanocomposites of urethane and montmorillonite clay in emulsion: In situ preparation and characterization

Nanocomposites of polyurethane‐montmorillonite (PU‐MMT) were successfully prepared by in situ emulsion polymerization. The PU‐MMT particles size in emulsion was controlled in nanolevel, which was confirmed by laser scattering size distribution analyzer. The morphology of MMT in PU‐MMT composites was observed by transmission electron microscopy (TEM). Wide angle x‐ray diffraction (WAXD) was also used to detect the dispersion of MMT in composites. The thermal property was evaluated by dynamic mechanical analysis. Mechanical and fracture properties were also been tested. Gas barrier property was discussed on the basis of testing oxygen permeability of PU‐MMT films. The permeability coefficient of the films is found to reduce after composing with MMT, which indicates that the potential application of PU‐MMT could be realized as coating materials to prevent metal rusting. It is also found that dimethyl distearylbenzyl ammonium chloride (DMDSBA) is a better modifier for MMT in PU than dimethyldistearyl ammonium chloride (DMDSA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(urethane‐benzoxazine)/clay hybrid nanocomposites

Poly(urethane‐benzoxazine)/clay hybrid nanocomposites (PU/Pa–OMMTs) were prepared from an in situ copolymerization of a polyurethane (PU) prepolymer and a monofunctional benzoxazine monomer, 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine (Pa), in the presence of an organophilic montmorillonite (OMMT), by solvent method using DMAc. OMMT was made from cation‐exchange of Na‐montmorillonite (MMT) with dodecyl ammonium chloride. The formation of the exfoliated nanocomposite structures of PU/Pa‐OMMT was confirmed by XRD from the disappearance of the peak due to the basal diffraction of the layer‐structured clay found in both MMT and OMMT. DSC showed that, in the presence of OMMT, the curing temperature of PU/Pa lowered by ca. 60°C for the onset and ca. 20°C for the maximum. After curing at 190°C for 1 h, the exothermic peak on DSC disappeared. All the obtained films of PU/Pa–OMMT were deep yellow and transparent. As the content of OMMT increased, both the tensile modulus and strength of PU/Pa–OMMT films increased, while the elongation decreased. The characteristics of the PU/Pa–OMMT films changed from plastics to elastomers depending on OMMT content and PU/Pa ratio. PU/Pa–OMMT films also exhibited excellent resistance to the solvents such as tetrahydrofuran, N,N‐dimethylformamide and N‐methyl‐2‐pyrrolidinone. The thermal stability of PU/Pa were enhanced remarkably even with small amount of OMMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4075–4083, 2003     

Effective preparation and characterization of montmorillonite/poly(ε‐caprolactone)‐based polyurethane nanocomposites

In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal stability and thermal oxidation kinetics of PU/CA-MMT composites

In this work, we prepared three composites polyurethane (PU)/chlorhexidine acetate (CA), PU/montmorillonite (MMT), and PU/CA-MMT, and investigated their kinetics of thermal degradation at different heating rates at atmosphere. These materials had good thermal stability and aging resistance. The thermal stability of PU/CA (T_onset: 237.3°C) was not obviously enhanced by the addition of only CA when compared with that of PU (T_onset: 232.3°C), while the thermal stability of PU/MMT (T_onset: 273.4°C) was considerably enhanced by the addition of MMT due to the high thermal stability of MMT. CA-MMT filler was dispersed and exfoliated in PU more easily than CA or MMT in PU, so the composite PU/CA-MMT possessed the best thermal stability (T_onset: 285.8°C). In addition, PU/CA-MMT also had the best resistance to bacterial adhesion and antibacterial ability. The analysis with Flynn-Wall-Ozawa method showed that the activation energy of thermal oxidation of PU increased when CA-MMT was added and thus its anti-aging ability was enhanced, and the thermal oxidation of these four materials was first-order reaction. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47002.