Structures,thermal stability,and crystalline properties of polyamide6/organic-modified Fe-montmorillonite composite nanofibers by electrospinning

In the present work, Fe-montmorillonite (Fe-MMT) was synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The polyamide6 (PA6)/organic-modified Fe-montmorillonite (Fe-OMT) composite nanofibers were prepared by facile compounding and electrospinning. Fe-OMT was first dispersed in N, N-dimethyl formamide and then compounded with PA6 which was dissolved in formic acid. The composite solutions were electrospun to form PA6/Fe-OMT composite nanofibers. The structure, morphology, thermal stability, and crystalline properties of the composite nanofibers were characterized by Fourier transfer infrared (FTIR) spectra, Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), High-resolution electron microscopy (HREM), Scanning electron microscopy (SEM), and Thermogravimetric analyses (TGA), respectively. It was found that the silicate clay layers were well exfoliated within the composite nanofibers and were oriented along the fiber axis. The SEM images indicated that the loading of Fe-OMT decreased the diameters of composite nanofibers. TGA analyses revealed that the thermal stability was notably improved in the presence of silicate clay. It was also observed from wide-angle XRD analyses that the presence of nanoclays improved the γ-form crystals and induced the formations of α-form crystals of the PA6, attributed to effective nucleating effects of silicate clay platelets.     

Synthesis and characterization of thermoplastic polyurethane/montmorillonite nanocomposites produced by reactive extrusion

The novel polyurethane/montmorillonite (PU/MMT) nanocomposites based on poly (propylene oxide) glycol (POP), 4,4′-diphenymethylate diisocyanate (MDI), 1,4-butanediol (1,4-BD) and MMT has been synthesized using a one-step direct polymerization-intercalation technique by twin-screw extruder. Its structure and thermal properties are characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and High-resolution electron microscopy (HREM), Fourier-transform infrared spectroscopy (FTIR) and Thermogravimetry analysis (TGA), respectively. The results of XRD and HREM analyses show that the silicate layer is well dispersed in PU matrix and this mesostructure can be considered as a delaminated nanocomposites. The TGA analysis indicates that the thermal stability properties of the PU/MMT nanocomposites are increased slightly compared with the pristine PU, due to the increase of the char residue. The mechanical and flammability performances are examined by electronic Universal Tester and Cone calorimetry, respectively. The layered silicate, which acts as a high aspect ratio reinforcement, enhances tensile strength of the PU. Specifically, there is a 25% increase in the tensile strength of PU nanocomposites containing 4 wt.% MMT compared with that of pristine PU. However, the elongation at break of PU/MMT nanocomposites is lower than that of pristine PU. The loading of MMT leads to the remarkably decrease of heat release rate (HRR), contributing to the improvement of flammability performance.     

Structural and thermal properties of polystyrene/CoAl-layered double hydroxide nanocomposites prepared via solvent blending: effect of LDH loading

Nanocomposites of polystyrene (PS) with modified CoAl-layered double hydroxide (CoAl–LDH) were prepared via simple solvent blending method and the effect of CoAl–LDH content on the structural and thermal properties was investigated. The structural and thermal properties of the nanocomposites were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The nano-scale dispersion of the CoAl–LDH layers in the PS matrix is verified by the (0?0?3) XRD reflection of the modified CoAl–LDH. The XRD data show that the exfoliated PS/CoAl–LDH nanocomposites can be obtained by controlling the LDH loading of about 5?wt%. TEM analysis also confirms the formation of exfoliated PS nanocomposites with 3?wt% and 5?wt% LDH loading. The thermal degradation temperature of the PS nanocomposite containing 5?wt% CoAl–LDH is found to be 12°C higher than that of pure PS when 50% weight loss is selected as a point of comparison. The glass transition temperature (T _g) of PS nanocomposites is about 14°C higher than that of pure PS.     

溶液插层法制备PPC/OMMT纳米复合材料及性能表征

通过溶液插层法制备了聚甲基乙撑碳酸酯/有机蒙脱土(PPC/OMMT)纳米复合材料,采用X射线衍射仪、热失重分析仪、透射电子显微镜(TEM)、动态力学性能测试仪(DMA)等对PPC/OMMT的性能进行了表征.XRD和TEM测试表明,OMMT均匀分散于PPC基体中并形成了插层型的纳米复合结构;DMA分析结果表明,复合材料的...     

PMB/GO纳米复合材料的制备及阻燃性能

用共混法制备甲基丙烯酸甲酯-丙烯酸丁酯共聚物(PMB)/氧化石墨(GO)纳米复合材料。采用X射线衍射(XRD)和透射电镜(TEM)对复合材料结构进行了表征,并采用热重分析法(TGA)和锥形量热分析(CONE)研究了其阻燃性能变化。XRD和TEM分析结果表明,复合物中添加GO形成剥离型结构的纳米复合材料。TGA研究发现复合材料的热稳定性得到提高。CONE的测试结果表明,GO极大地改善了体系的燃烧性能,其中加5%GO体系的pk-HRR降低了62.2%。     

Structure and mechanical properties of polycarbonate modified clay nanocomposites

Polycarbonate (PC)/modified clay nanocomposites were prepared, in the absence and presence of different amounts of maleic anhydride grafted polypropylene (PP-g-MA), by direct melt blending. Their structures, as well as mechanical, morphological and thermal properties, were characterized by X-ray diffractometry (XRD), tensile testing, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The XRD results of the PC/clay nanocomposites showed that they had intercalated structures, although some exfoliation was visible at low clay contents, that the gallery heights of the PC/clay nanocomposites were almost the same, and that some of the clay layers collapsed as a result of modifier decomposition at the high processing temperature. The XRD patterns of the PC/PP-g-MA/clay nanocomposites clearly show less intercalation and more exfoliation with increasing PP-g-MA content. These results were supported by TEM observations. Both the tensile strength and modulus show substantial improvements with both increasing clay and PP-g-MA contents, while the elongation at break substantially decreases, although the presence of PP-g-MA somewhat improves these values. All the nanocomposites have lower thermal stability than pure PC, but the presence of PP-g-MA seems to improve the thermal stability of these samples.     

Preparation and characterization of poly (styrene-acrylonitrile) (SAN)/clay nanocomposites by melt intercalation

Poly (styrene-acrylonitrile) (SAN)/clay nanocomposites have been prepared by melt intercalation method from pristine montmorillonite (MMT), using hexadecyl trimethyl ammonium bromide (C16) and hexadecyl triphenyl phosphonium bromide (P16) as the reactive compatibilizers between polymer and clay. The influence of the reactive compatibilizers proportion relative to the clay on the structure and properties of the SAN/clay nanocomposites is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), high-resolution electron microscopy (HREM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The effects of the two different clays (MMT and organic modified MMT) on the nanocomposites formation, morphology and property are also studied. The results indicate that the SAN cannot intercalate into the interlayers of the MMT and results in microcomposites. In the presence of the reactive compatibilizers, the dispersion of clay in SAN is rather facile and the SAN/clay nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and the presence of small tactoids. The appropriate proportion with 3 wt% reactive compatibilizers to 5 wt% MMT induces well-dispersed morphology and properties in the SAN matrix. The TGA analyses show that the thermal stability properties of the SAN/clay nanocomposites have been improved compared with those of the pristine SAN. The DMA results show that the storage modulus and glass transition temperature (Tg) of the SAN/clay nanocomposites have remarkably enhancements compared with the pristine SAN. At last the intercalation mechanism of the technology is discussed.     

The effect of photo-oxidation on thermal and fire retardancy of polypropylene nanocomposites

Nanocomposites of polypropylene-graft-maleic anhydride/clay were prepared by melt blending in an extruder mixer. The nanoscale dispersion of the clay in the polymer was analysed by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of XRD and TEM showed that the nanocomposites obtained were a kind of intercalated-delaminated structures side by side with different dominant states, depending on the clay used and on the processing conditions. The consequences of photo-oxidation on the thermal stability and fire retardant properties of the nanocomposites were investigated using thermogravimetric analysis and cone calorimetry tests. It appeared that this degradation dramatically affected the important properties of the nanocomposites. A loss of thermal stability and fire retardant performance was observed. This was ascribed to scission reactions that occurred during the oxidative degradation prior to thermal and fire tests.     

Magnesium hydroxide sulfate hydrate whisker flame retardant polyethylene/montmorillonite nanocomposites

Flame retardant maleated polyethylene/magnesium hydroxide sulfate hydrate whisker (MAPE/MHSH) composites containing organo-modified montmorillonite (OMT) were prepared by direct melt intercalation. Their morphology, combustion behaviour and thermal stability were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), cone calorimetry and thermogravimetric analyses (TGA). The exfoliation of silicate layers within MAPE has been verified by XRD and TEM images. Cone calorimetry results indicated that a synergistic flame retardant effect on reducing heat release rate (HRR) occurred when MHSH and OMT were both present in nanocomposite. The reduction in HRR improved as the mass fraction of OMT was increased from 2 to 10 wt%, but there was little improvement above 5 wt% OMT loading level. TGA profiles of the nanocomposites revealed that the thermodegradation stability of the nanocomposites decreased as the OMT fraction increased from 2 to 10 wt%.     

Core-shell magnesium hydroxide/polystyrene hybrid nanoparticles prepared by ultrasonic wave-assisted in-situ copolymerization

In this paper, vinylated magnesium hydroxide (MH) nanosheets were prepared with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and pristine MH nanosheets, then the MH/polystyrene (PS) hybrid nanoparticles were prepared by ultrasonic wave-assisted in-situ copolymerization of vinylated MH nanosheets and styrene (St). The morphology, thermal stability and chemical structure of the final products were investigated in detail with transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR). The TEM and FTIR results showed that the uniformly-dispersed core-shell structure of MH/PS nanocomposites with MH-cores and PS-shell was formed. TGA indicated that the covalent interaction between PS and MH improved the thermal stability of PS. A possible formation mechanism of the MH/PS core-shell nanocomposites was also proposed.     

原位插层聚合尼龙6/超分散有机蒙脱土剥离型纳米复合材料的结构和性能

采用原位插层聚合法制备了尼龙6/蒙脱土剥离型纳米复合材料,讨论了超分散有机蒙脱土的用量对复合材料性能的影响,用动态力学分析(DMA)、X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等手段研究了纳米复合材料的结构和性能。结果表明,有机蒙脱土加入量为3%(质量分数,下同)时,复合材料综合性能最佳;有机蒙脱土的加入大大提高了尼龙6的综合性能,并提高了尼龙6的储能模量和玻璃化温度。有机蒙脱土在尼龙6基体中有良好的分散性和相容性,蒙脱土片层被完全剥离,在尼龙6基体中实现了纳米级分散。     

Layered double hydroxide as nanofiller in the development of polyurethane nanocomposites

Polyurethane (PU)/Dodecyl sulphate intercalated layered double hydroxide (DS-LDH) nanocomposites were successfully synthesized from PU prepolymer and polyol TG (mixtures of glycerol and trimethylolpropane) for the first time. Formation of partially exfoliated structures of PU/DS-LDH nanocomposites was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Analysis of tensile properties showed significant improvements in tensile strength (TS) and elongation at break (EB) of about 407% and 83% for PU/DS-LDH (3 wt%) nanocomposite. The observed excellent concurrent improvement in TS and EB is attributed to the relatively better reinforcing effect of partially exfoliated DS-LDH layers in PU making the present investigation most noteworthy. In addition, gradual improvement in thermal stability and limiting oxygen index (LOI) with increasing DS-LDH loading makes these nanocomposites versatile and hence suitable for many critical applications.     

阳离子表面活性剂为乳化剂原位乳液聚合制备PS/MMT纳米复合材料

针对原位乳液聚合法制备聚合物/蒙脱土(MM T)纳米复合材料,为了实现蒙脱土片层的有机化处理和纳米复合材料的形成一步完成,以十六烷基三甲基溴化铵为乳化剂原位乳液聚合制备了PS/MM T纳米复合材料。XRD、FT-IR、TEM等分析表明,聚苯乙烯已插层进入蒙脱土的层间。在制备过程中,CTAB既充当了乳化剂,又充当了蒙脱土的插层处理剂,促进了苯乙烯在蒙脱土层间的聚合,同时也造成了蒙脱土片层一定程度的聚并。DSC分析表明,复合物的玻璃化转变温度有一定程度的提高。另外,还对蒙脱土存在下乳液聚合的特点进行了研究,发现MM T片层对乳液聚合的影响仅在聚合反应的初始阶段,使聚合速率有所下降,而对反应的后期阶段和反应产物的分子量影响不大。     

Solvothermal synthesis of carbon nanostructure and its influence on thermal stability of poly styrene

Carbon nanostructures were synthesized via a novel solvothermal reaction between ferrocene and sulfur. Carbon nanostructures were then added to poly styrene (PS) matrix. The thermal stability behavior of PS filled with carbon nanostructures were investigated by thermogravimetric analysis (TGA). Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDS) analysis and atomic force microscopy (AFM). The flame retardancy behavior of PS–carbon was studied by UL-94 analysis.     

Synthesis and properties of melamine-formaldehyde/ montmorillonite nanocomposites

In this paper, intercalated and partially exfoliated melamine-formaldehyde (MF)/montmorillonite (MMT) nanocomposites have been synthesized successfully via in-situ polymerization based on pristine montmorillonite, acidified montmorillonite and organic modified montmorillonite respectively. The obtained nanocomposites were characterized by XRD, TEM, TGA, and Raman spectroscopy. Free formaldehyde content of those composites was also determined by acetyl acetone technique. It was found that acidified montmorillonite and organic modified montmorillonite could catalyze the polycondensation reaction of methylolmelamines. The thermal stability and chemical resistance of those two nanocomposites were also improved dramatically compared to pure melamine-formaldehyde resin.     

Poly(butylene terephthalate)/organoclay nanocomposites prepared by in-situ bulk polymerization with cyclic poly(butylene terephthalate)

The PBT/organoclay nanocomposites were prepared with cyclic poly(butylene terephthalate) oligomers and organically modified clay via in-situ bulk polymerization. Dispersion of the clay layers in the PBT nanocomposites was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability of the nanocomposites was studied by thermal gravimetric analyses (TGA). These results indicate that organoclay has been dispersed homogeneously in the PBT matrix, and the nanocomposites with intercalated-exfoliated structure were synthesized via this method. The onset degradation temperature of the nanocomposites was increased by 8-10 °C compared with the PBT homopolymer without any clay.     

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.     

Preparation and properties of nitrile rubber/montmorillonite nanocomposites via latex blending

The nitrile rubber (NBR)/unmodified montmorillonite (Na-MMT) clay nanocomposites were prepared by latex blending method followed by melt mixing of compounding ingredients by using two-roll mill. The X-ray diffraction (XRD) studies showed an increase in the basal spacing and broadening of peak corresponding to crystal structure of Na-MMT indicating the formation of intercalated/exfoliated clay layers in the NBR matrix. Increase in clay content of nanocomposite increased the XRD peak height due to the formation of many of clay tactoids at higher loading. The transmission electron microscopy (TEM) strengthened the XRD finding by showing the presence of intercalated/exfoliated morphology of clay platelets having good dispersion. The modulus and tensile properties of the nanocomposites were improved with addition of Na-MMT which is proportional to clay concentration. The retention of tensile properties of aged nanocomposites, with all clay concentration, was superior to either pure NBR and carbon black filled NBR composite. The dynamic mechanical analysis showed proportional increase in storage modulus analogous to Na-MMT loading at all the temperature ranges due to the confinement of polymer chains between the clay layers. Nanocomposites with different proportions of clay showed a decrease in tan δ_max peak height with a shift towards higher temperature indicating the reduction in the segmental mobility of polymer chain. A linear model was proposed to correlate the influence of Na-MMT content on storage modulus of nanocomposites. Differential scanning calorimetry indicated a linear increase in glass transition of nanocomposites which is proportional to clay loading. Thermogravimetric analysis revealed a small improvement in the thermal stability of nitrile rubber/clay nanocomposites.     

Studies on the preparation and structure of polyacrylamide/α-zirconium phosphate nanocomposites

In this paper, a novel polyacrylamide(PAM)/α-zirconium phosphate(α-ZrP) nanocomposite was successfully synthesized by exfoliation-adsorption and in-situ intercalative polymerization. The microstructure of PAM/α-ZrP nanocomposites was confirmed by X-ray diffraction measurement, transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM). The results suggested that the α-ZrP lamellae were dispersed well in PAM matrix, which indicated the formation of the exfoliated nanocomposites in the low inorganic loading of α-ZrP (≤5 wt%). With the increase of the inorganic loadings, the intercalated structure of PAM/α-ZrP nanocomposites was dominant with the d-spacings of about 1.50–1.58 nm corresponding to the inorganic loadings in the range of 10–20 wt%. Moreover, besides the electrostatic adsorption, it was also found that there may be some weak effect such as hydrogen bonding or protonation between the host and guest investigated using fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG )analysis, which resulted in the enhancement of the thermal properties on the decomposition process of PAM/α-ZrP nanocomposites by the retardant effect of the exfoliated or intercalated α-ZrP nanometer lamellae.     

C(60) reduces the flammability of polypropylene nanocomposites by in situ forming a gelled-ball network

The thermal and flame retardancy properties of polypropylene/fullerene (PP/C(60)) nanocomposites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cone calorimetry with the C(60) loading varied from 0.5 to 2% by weight. Dispersion of C(60) in the PP matrix was characterized by transmission electron microscopy (TEM) and optical microscopy (OM). TGA and DSC results showed that the presence of C(60) could remarkably enhance the thermal property and cone calorimeter measurements suggested that C(60) could to some extent reduce the flammability of PP, with a significant reduction in peak heat release rate and a much longer time to ignition. Furthermore, the larger the loading level of C(60), the better the flame retardancy property of PP/C(60) nanocomposites. The flame retardation mechanism and corresponding model were proposed with the help of rheological measurements, TEM and x-ray diffraction. C(60) reduced the flammability of PP by trapping free radicals in the gas phase and in situ forming a gelled-ball crosslink network to improve the flame retardancy of PP in the condensed phase. Finally, this suggested mechanism was supported by the results of advanced rheological extended systems (ARES), gel content, infrared spectrum, OM, and atomic force microscopy (AFM) measurements.