Study on morphology and characterization of poly(mphenylene isophtalamide)/multi-walled carbon nanotubes composite nanofibers by electrospinning

Electrospinning technique is the main method of preparing polymer nanofiber simply, directly and continuously at present. In this work, electrospinning blend solution was prepared by in-situ polymerization using acid-modified multi-walled carbon nanotubes (MWNTs), m-phenylenediamine (MPD) and isophthaloyl chloride (IPC). And then composite nanofibers were prepared by electrospinning. MWNTs played an important role in nanofiber's properties. The effects of MWNTs on the morphology and characterization of the MWNTs/PMIA composite nanofibers were investigated. Scanning electron microscopy (SEM), thermal gravimetric analyzer (TGA), and X-ray diffraction (XRD) were utilized to characterize the MWNTs/PMIA nanofibers morphology and properties. The experimental results indicated that the nanofibers diameter decreased and solution dynamic viscosity increased with increasing MWNTs contents. XRD data demonstrated that PMIA composite nanofibers had the same crystal type as the pure PMIA nanofiber, and crystallinity was improved with increasing MWNTs loading. Transmission electron microscopy (TEM) was used to confirm MWNTs aligned along the axis of composite nanofibers.     

Synthesis and properties of polystyrene/Fe-montmorillonite nanocomposites using synthetic Fe-montmorillonite by bulk polymerization

Fe-montmorillonite (Fe-MMT) was hydrothermally synthesized. It was modified by cetyl trimethylammonium bromide (CTAB) and successfully synthesized polystyrene/Fe-montmorillonite (PS/Fe-MMT) nanocomposites via bulk polymerization for the first time. The resulting nanocomposites were characterized by X-ray diffraction (XRD) spectra, transmission electron microscopy (TEM), high resolution electronic microscopy (HREM), thermal gravimetric analysis (TGA) and cone calorimeter. XRD, TEM and HREM indicated that both intercalated and exfoliated-intercalated structures were observed. In comparison with pure PS, the thermal stability was notably improved in the presence of clay. From cone calorimetry it was found that the peak of heat release rate (HRR) was significantly reduced by the formation of the nanocomposites. Also intercalated nanocomposites were more effective than exfoliated-intercalated nanocomposites in fire retardancy.     

A simple route to disperse silver nanoparticles on the surfaces of silica nanofibers with excellent photocatalytic properties

In this work, monodispersed silver nanoparticles decorated SiO₂ nanofibers were synthesized by electrospinning method, followed by thermal treatment at 600 °C. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) were used to characterize the composite nanofibers. Accordingly, the detailed formation mechanism of SiO₂/Ag composite nanofibers was discussed. Furthermore, an excellent catalytic activity of SiO₂/Ag composite fibers was observed by a degradation reaction of methyl orange (MO) dye.     

Morphology,thermal and mechanical behavior of polyamide 6/layered-silicate nanocomposites

The microstructure, morphology, thermal and mechanical properties of polyamide 6/layered-silicate nanocomposites (PLSN) have been studied using X-ray diffraction (XRD), tapping-mode atomic force microscopy (AFM), differential scanning calorimetry (DSC) and tensile tests. The XRD and AFM results indicate that the organically-modified layered silicates are intercalated in the polyamide 6 (PA6) matrix. Also, the crystallization and thermal behavior of PA6 are influenced by the addition of layered silicates into polymer matrix. A silicate-induced crystal transformation from the α-form to the γ-form of PA6 is confirmed by XRD and DSC, i.e., the formation of γ crystal is enhanced by the presence of silicates. In comparison to PA6, the thermal property of PLSN has been investigated using DSC. The possible origins of a new silicate-induced endothermic peak are discussed. Tensile tests show that the tensile modulus and yield strength increase while the strain-at-yield decreases with increasing clay loading.     

Iron-montmorillonite and zinc borate as synergistic agents in flame-retardant glass fiber reinforced polyamide 6 composites in combination with melamine polyphosphate

This paper presents a preliminary investigation on the effects of organically modified iron-montmorillonite (Fe-OMT) and zinc borate (ZnB) on thermal degradation behaviors and flame retardancy of melamine polyphosphate (MPP) flame-retarded glass fiber reinforced polyamide 6 (GFPA6). The samples were characterized using limiting oxygen index (LOI), UL-94 tests, thermogravimetric analysis (TGA), Fourier transform infrared coupled with the thermogravimetric analyzer (TG-FTIR) and Microscale Combustion Calorimeter (MCC) measurements. The residue after LOI test was also analyzed by Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman spectroscopy. A substitution of a certain fraction of MPP with ZnB or Fe-OMT can significantly improve the UL-94 rating of GFPA6/MPP composites from no rating to V0 rating, exhibiting excellent flame retardacny. Based on the investigations, different flame retardant mechanisms were proposed for the two effective flame-retardant formulations.     

Lecithin blended polyamide-6 high aspect ratio nanofiber scaffolds via electrospinning for human osteoblast cell culture

In this study, we focused on the preparation and characterization of lecithin blended polyamide-6 nanofibers via an electrospinning process for human osteoblastic (HOB) cell culture applications. The morphological, structural characterizations and thermal properties of polyamide-6/lecithin nanofibers were determined by using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). SEM images revealed that the nanofibers were well-oriented with good incorporation of lecithin. FT-IR results indicated the presence of amino groups of lecithin in the blended nanofibers. TGA analysis revealed that the onset degradation temperature decreased with increasing lecithin content in the blended nanofibers. The morphological features of cells attached on polyamide-6/lecithin nanofibers were confirmed by SEM. The adhesion, viability and proliferation properties of osteoblast cells on the polyamide-6/lecithin blended nanofibers were analyzed by in vitro cell compatibility test. This study demonstrated the non-cytotoxic behavior of electrospun polyamide-6/lecithin nanofibers for the osteoblast cell culture.     

Preparing PP/clay nanocomposites using a swelling agent

Polypropylene (PP)/clay nanocomposites (PPCN) were prepared using a swollen organoclay, which had a larger interlayer spacing than pristine organoclay. The organoclay was first treated with a swelling agent (maleic anhydride, MA) and a co-swelling agent in solution. Then, it was melt blended with PP-g-MA to generate a pre-intercalated composite (PIC). Finally, the PIC was blended with PP to obtain a PPCN, which contained small amounts of PP-g-MA. The materials were characterized using X-ray diffraction (XRD), Scanning electron microscopy, Transmission electron microscopy (TEM), and TGA. The XRD graphs showed that the basal spacing of the pristine clay treated with MA was 1.6 nm, which was larger than that of the original clay, but smaller than that of the organoclay. The XRD graphs of the organoclay treated with MA showed double peaks at 3 and 5.5°. As the ratio of MA to the organoclay increased, the peak at 5.5° decreased gradually. TEM micrographs indicated that the clay layers in the pre-intercalated blends were still stacked in an orderly manner. However, partial exfoliation of the clay layers was observed in the PPCN. The nanocomposites prepared with the aid of swelling agents contained some PP-g-MA. Good dispersion of the clay layers gave the PPCN greater thermal stability and an enhanced storage modulus, which indicated a reinforcing effect of the clay in the PP matrix. The increased T_g (derived from Dynamic mechanical analysis) of PPCN implied that the PP macromolecules were intercalated between interlayers of the silicate.     

Preparation and characterization of silica nanoparticulate-polyacrylonitrile composite and porous nanofibers

In this study, polyacrylonitrile (PAN) composite nanofibers containing different amounts of silica nanoparticulates have been obtained via electrospinning. The surface morphology, thermal properties and crystal structure of PAN/silica nanofibers are characterized using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, wide-angle x-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results indicate that the addition of silica nanoparticulates affects the structure and properties of the nanofibers. In addition to PAN/silica composite nanofibers, porous PAN nanofibers have been prepared by selective removal of the silica component from PAN/silica composite nanofibers using hydrofluoric (HF) acid. ATR-FTIR and thermal gravimetric analysis (TGA) experiments validate the removal of silica nanoparticulates by HF acid, whereas SEM and TEM results reveal that the porous nanofibers obtained from composite fibers with higher silica contents exhibited more nonuniform surface morphology. The Brunauer-Emmett-Teller (BET) surface area of porous PAN nanofibers made from PAN/silica (5?wt%) composite precursors is higher than that of pure nonporous PAN nanofibers.     

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%.     

Morphological and thermomechanical characterization of thermoplastic starch/montmorillonite nanocomposites

A combination of starch and clay for the preparation of nanocomposite materials is proposed. In this work, starch was plasticized by pequi (Caryocar brasiliense) oil, and thermoplastic starch (TPS)/montmorillonite (MMT) nanocomposites were analyzed by X-ray diffraction (XRD), thermogravimetry (TG), thermomechanical analyses (TMA) and scanning electron microscopy (SEM). Exfoliated and intercalated nanocomposites were found to be dependent on MMT content. Exfoliation is the predominant mechanism of clay dispersion for low filler loading. Increase of the clay loading (>5 wt.%) causes intercalation. The introduction of low content (?5 wt.%) of MMT improves the thermal stability and the stiffness of the materials. There is a limit content of clay that can be added to improve the thermal and thermomechanical properties of the composites. Beyond that value the composite presents properties below the original polymer.     

静电纺丝法制备PAN/Fe3O4磁性纳米纤维

采用化学共沉淀法制备纳米四氧化三铁,选用曲拉通X-100为分散剂,利用静电纺丝法制备PAN/Fe3O4磁性纳米复合材料。X射线衍射仪(XRD)验证了四氧化三铁在复合纳米纤维中的存在。同时使用扫描电镜(SEM)和透射电镜(TEM)对复合纳米纤维的微观形貌和Fe3O4在纤维中的分布进行了观察,利用热重(TGA)对纳米复合材料的热稳定性进行分析;通过磁性实验分析了纳米复合材料的磁性性能。结果表明,所制备PAN/Fe3O4磁性纳米纤维成型良好,且Fe3O4磁性颗粒在纤维中分散均匀,其与PAN是物理复合。纳米复合材料具有一定磁性,并可由磁性颗粒的加入量进行控制。     

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.     

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 biodegradability of starch-g-ethyl methacrylate/sodium acrylate/sodium silicate superabsorbing composite

A new superabsorbent composite polymer (SAP) has been prepared by graft copolymerization reaction using starch, ethyl methacrylate (EMA), benzoyl peroxide (BPO) as initiator and sodium acrylate as crosslinking agent. Further, it is observed that the composite doped with sodium silicate exhibits higher waterabsorbency as the silicate can well disperse in the water and enter into the network structure of the composite, thereby increasing the porosity of the composite. Sodium acrylate plays an important role as the crosslinker forming a network structure of the superabsorbent composite. The composite was characterized by IR, TGA, and XRD methods. The biodegradability of these valuable novel materials was evaluated for their industrial and commercial importance. The surface morphology was compared by scanning electron microscopy (SEM) before and after biodegradation of the composite.     

Synthesis of calcium carbonate-polyethylene oxide hybrid nanofibers through in-situ electrospinning

In this work, calcium carbonate nanoparticles-polyethylene oxide nanofibers as organic-inorganic hybrid were prepared via in-situ electrospinning. Thus, electrospinning of polyethylene oxide solution saturated with calcium hydroxide was carried out in gaseous carbon dioxide atmosphere. Transmission electron microscopy (TEM) showed that calcium carbonate (CaCO3) nanoparticles were formed on the produced nanofibers of 200-300 nm in diameter. The existence of the formed CaCO3 was also proved by thermogravimetric analysis (TGA) via loss of gaseous CO2 related to the decomposition of CaCO3 at about 500-840 degrees C. X-ray diffraction (XRD) analysis of the nanofibers showed that the formed CaCO3 nanoparticles have vaterite morphology. DSC analysis was used to determine melting point and to calculate the crystallinity of the produced hybrid nanofibers. The TEM, TGA, XRD and DSC analyses results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution and polyethylene oxide solution having calcium hydroxide, both in air.     

单晶PZT-CFO铁电-铁磁复合纳米纤维的制备与磁学性能研究

以不同锆掺杂量的前钙钛矿结构钛酸铅和铁酸钴为原料,采用原位固相烧结法合成了一系列单晶锆钛酸铅-铁酸钴(PZT-CFO)复合纳米纤维。X射线衍射、扫描电子显微镜和能谱分析结果表明,一维单晶PZT-CFO复合纳米纤维同时存在钙钛矿相的锆钛酸铅和尖晶石相的铁酸钴。高分辨透射电子显微镜研究证实锆钛酸铅和铁酸钴之间存在外延生长关系。采用振动样品磁强计对PZT-CFO复合纳米纤维的磁学性能进行测试,发现该复合纳米纤维具有明显的铁磁性能,其剩余磁化强度和矫顽力随着锆掺杂量的增加而增加。     

静电纺丝法制备金纳米粒子/PVP复合纳米纤维

采用水合肼还原一定浓度氯金酸溶液的方法,在聚乙烯吡咯烷酮(PVP)作保护剂的乙醇/水溶液中,成功制备出粒度较小,且高度分散的金溶胶,紫外吸收光谱证实了溶液中金纳米粒子的存在.采用静电纺丝技术制备了AuNs/PVP复合纳米纤维.采用扫描电镜(SEM)和X射线衍射(XRD)等分析手段对纤维的表面形貌等进行了表征.由扫描电镜...     

利用静电纺丝技术制备纳米黏土/聚乳酸复合纳米纤维与其表征

利用静电纺丝技术制备了纳米黏土/聚乳酸(PLA)复合纳米纤维,并将该复合纳米纤维收集成无纺布薄膜,采用SEM和TEM观察了复合纳米纤维的微观形貌和结构,分别利用XRD和TGA测试了复合纳米纤维的结晶行为及热学行为,并分析了复合纳米纤维薄膜的拉伸力学性能随纳米黏土含量的变化关系。结果表明:当PLA含量为10wt%、纳米黏土含量为1wt%、CHCl3与DMF体积比为3∶1溶剂条件下,所制备的纳米黏土/PLA复合纳米纤维的细度和均匀性均得到改善;XRD测试结果表明,纳米黏土成功附着在PLA中。TGA和力学测试结果表明,纳米黏土/PLA复合纳米纤维的热稳定性和力学性能相对于纯PLA纤维有较大幅度提高,当纳米黏土含量为1wt%时,其初始分解温度提高了60℃,拉伸强度、断裂伸长率和弹性模量分别提高了111.3%、74.9%和20.0%。     

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 thermal properties of form-stable palmitic acid/active aluminum oxide composites as phase change materials for latent heat storage

Form-stable palmitic acid (PA)/active aluminum oxide composites as phase change materials were prepared by adsorbing liquid palmitic acid into active aluminum oxide. In the composites, the palmitic acid was used as latent heat storage materials, and the active aluminum oxide was used as supporting material. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine the chemical structure, crystalloid phase and microstructure of the composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The FT-IR analyses results indicated that there is no chemical interaction between the palmitic acid and active aluminum oxide. The SEM results showed that the palmitic acid was well adsorbed into porous network of the active aluminum oxide. The DSC results indicated that the composites melt at 60.25 °C with a latent heat of 84.48 kJ kg⁻¹ and solidify at 56.86 °C with a latent heat of 78.79 kJ kg⁻¹ when the mass ratio of the PA to active aluminum oxide is 0.9:1. Compared with that of the PA, the melting and solidifying time of the composites CPCM5 was reduced by 20.6% and 21.4% because of the increased heat transfer rate through EG addition. The TGA results showed that the active aluminum oxide can improve the thermal stability of the composites.