Effect of silane functionalization of montmorillonite on epoxy/montmorillonite nanocomposite

Mechanical and dynamic mechanical properties of various montmorillonite (MMT)/epoxy nanocomposites were investigated. 3-aminopropyltriethoxysilane functionalized MMT was compared with commercial pristine MMT and ammonium salt substituted MMT. Qualitative evidence of silane functionalization was confirmed by FT-IR. XRD and TEM were used to characterize the degree of intercalation of MMT in epoxy nanocomposite. Tensile stress and elongation of MMT/epoxy nanocomposite were improved significantly by the silane functionalization of MMT. Dynamic mechanical analysis showed that silane functionalization of MMT resulted in active interactions between MMT and epoxy.     

Nitrogen adsorption method for determining the mesopore slit-like size distribution of expansive soils

One of the most important structural parameters involved in the characterization of the void space of soils is the pore size distribution. In this work, a nitrogen adsorption method is presented as an alternative to determine the mesopore contribution of slit-shaped pores to the abovementioned parameter in montmorillonite-containing soils. The mesopore size structural parameter obtained via this sorption method is related to montmorillonite d₀₀₁ interlayer distances proceeding from either X-ray or electron diffraction analysis, if only by assuming during sorption analysis that mesopores resident inside clay grains adopt slit-shaped geometries. Mineralogical analysis and determination of some important geotechnical properties of these montmorillonite-containing soils complement the preceding sorption and structural studies.     

Polyimide/montmorillonite nanocomposites based on thermally stable, rigid-rod aromatic amine modifiers

The preparation and processing of most of polymer/clay nanocomposites need high temperature. This limited the application of commonly used organic modifiers of long carbon-chain alkyl ammonium salts because of their low thermal stability. In this study, we synthesized two novel thermally stable, rigid-rod aromatic amines. Montmorillonite (MMT) treated by these amines exhibited larger layer-to-layer spacing, higher thermal stability than that treated by commonly used 1-hexadecylamine and also high ion-exchange ratio (>95%). They were applied to prepare nanocomposites with polyimide (PI) by in situ polymerization. XRD, TEM were used to obtain the information on morphological structure of PI/MMT nanocomposites. DMA, TGA, DSC, universal tester were applied to characterize the mechanical and thermal properties of the nanocomposites. When the MMT content was below 3 wt%, the PI/MMT nanocomposites were strengthened and toughened at the same time. The introduction of a small amount of MMT also led to improvement in thermal stability, slight increase in glass transition temperature, marked decrease in coefficient of thermal expansion and decrease in solvent uptake. MMT treated by these aromatic amines exhibited better dispersibility and (probably) interfacial interaction with PI matrix than that treated by 1-hexadecylamine. The nanocomposites based on these MMT resultantly exhibited better mechanical, thermal and solvent resistance properties than those based on 1-hexadecylamine treated MMT.     

Olive mill wastewaters decontamination based on organo-nano-clay composites

Green composites for environmental applications were successfully prepared by intercalation of the biosurfactant Quillaja saponin onto montmorillonite mineral clay on varying pH and surfactant/clay ratio. Equilibrium adsorption isotherms were constructed and the system was characterized by performing TGA and XRD analyses.The efficiency of the surfactant-modified clay in the removal of the organic content present in olive mill wastewaters (OMW) was evaluated by means of spectrophotometric measurements. The interest for this cogent issue comes from the consideration that, despite their high pollutant content, OMW can be considered as a potential resource of several organic compounds which can be recovered for a wide array of pharmaceutical and industrial applications. Two different strategies were proposed. In the first one, dried surfactant/clay hybrids were added to the batch samples under continuous stirring, while in the second alternative approach the organoclays were packed in chromatography column filled with multiple alternate layers of sand and organoclay.These studies revealed the efficacy of the methods used and suggested that the modification of the montmorillonite clay substrate significantly improves the performance of the clay.     

PVC/聚烯烃/蒙脱土纳米复合材料的制备与性能研究

将钠基蒙脱土(MMT)预先负载小分子单体丙烯酰胺(AM)和引发剂过氧化二异丙苯，然后与PVC／PE或PVC／PP在双辊上进行插层复合，制成了PVC／聚烯烃／蒙脱土纳米复合材料，对复合材料进行了表征。结果表明：吸附丙烯酰胺后蒙脱土的层间距有所增大，AM-MMT填充的复合材料属于插层型纳米复合材料，PP复合材料比PE复合材料更容易插层蒙脱土；纳米复合材料的拉伸强度和冲击强度都随AM-MMT用量的增加有一最大值；DSC显示插层效果较好的纳米复合材料的Tg较低。     

Investigation of polymer and nanoclay orientation distribution in nylon 6/montmorillonite nanocomposite

A method to determine the orientation distribution function of montmorillonite clay in nylon 6 nanocomposite films by a combination of infrared (FTIR) trichroic analysis and transmission electron microscopy (TEM) image analysis is described. The structural absorbance of the nanoclay Si-O vibrations was obtained by the sample tilting method described by Schmidt [Schmidt PG. J Polym Sci: Part A 1963;1:1271-1292]. A nonlinear least squares regression was performed to extract the absorbance of individual peaks. The montmorillonite clay orientation in spun cast nylon 6 films can be described by a Gaussian function having a standard deviation of 15° i.e. 95% of the clay platelets are tilted at an angle of within ±30° of the plane of the film. The transition dipole moment angles of the 1018 and 1046 cm⁻¹ clay vibrations are determined to be 18 and 16° relative to the clay surface, respectively. The orientation of nylon 6 in the nanocomposite was also investigated based on the NH stretching mode. The NH bonds are found to be less preferentially oriented along the plane of the film surface compared to pure nylon 6 film.     

The role of plasticizer on the exfoliation and dispersion and fracture behavior of clay particles in PVC matrix: a comprehensive morphological study

The clay nanoparticles are readily dispersed and exfoliated in the PVC matrix with the help of Dioctyl phthalate (DOP) plasticizer. X-ray, TEM and AFM analysis of the nanocomposites indicate that there is an optimum concentration of DOP for the process. If used in high concentrations, the ability to transfer forces to the clay particles through the polymer matrix decreases due to substantial decrease in viscosity. The individual platy montmorillonite particles dispersed in PVC matrix were directly observed by AFM and found to lie preferentially on their basal surfaces, especially when the compounded batch is compression molded. The edges of the particles were in some cases straight forming hexagonal angles and in other cases irregular.     

Synthesis of polyamide-imide-montmorillonite-nanocomposites via new approach of in situ polymerization and solvent casting

Due to the inherent importance of nanostructuring in coatings the present article provides a new approach for exfoliation of montmorillonite via in situ polymerization in comparison to solvent casting method. The new in situ polymerization with PAI was realized by swelling MMT's intergallery with p-chlorphenole blocked 4,4′-methylene diphenyl diisocyanate and 1,2,4-benzenetricarboxylic acid anhydride followed by polymerization within MMT's intergalleries. XRD-measurements and SEM analysis at cross-sections revealed nanocomposites with exfoliated sheet structure up to 2.0 wt% MMT while for solvent casting 1.2 wt% was determined as limiting concentration. Therefore, this novel approach provides synthesis of higher concentrated exfoliated PAI-MMT-nanocomposites. Despite its disadvantage in lower limiting concentration, when it comes to application, the solvent casting method turned out to be superior to in situ polymerization as it is much faster and economically more feasible.     

Epoxy reinforcement with silicate particles: Rheological and adhesive properties – Part I: Characterization of composites with natural and organically modified montmorillonites

Rheological and adhesive properties of epoxy oligomer–montmorillonite (MMT) nanocomposites containing 2 and 5 wt% of natural and organomodified clay were studied. Ultrasound treatment of epoxy–clay systems was used for their homogenization. According to rheological data, ultrasound stirring allows the development of well-dispersed systems in the case of organomodified MMT. Sonication of composites with natural clay is inefficient and leads to a poorly dispersed structure. X-ray data demonstrate increases in the interlaminar spacing for organomodified MMT (up to 2 times), which is indicative of MMT intercalation. Clay addition leads to 40–65% increase in the shear adhesion strength of the cured epoxy resin. The sonication influence on the shear adhesion strength of the system with 2 wt% of any clay is very small. Ultrasound stirring of the systems with 5 wt% of clay results in higher values of adhesion for organomodified MMT.     

PET／蒙托土纳米复合材料的结晶行为

用示差扫描量热计（ＤＳＣ）研究了ＰＥＴ／蒙托土纳米复合材料的结晶行为,并与未填充ＰＥＴ进行了比较。结果表明：分散在ＰＥＴ基体中的蒙托土纳米微粒对ＰＥＴ的结晶具有异相成核作用;但蒙托土微粒表面与ＰＥＴ之间很强的界面作用限制了ＰＥＴ分子链段的运动,使晶体生长受到阻碍;因此总结晶速率取决于两方面的综合效应。ＰＥＴ／蒙托土纳米复合材料的结晶完善程度变差,熔点和熔融热下降,同时结晶活化能明显增大。