The aim of this study was to assess the effect of montmorillonite nanofillers, Cloisite Na+ and Cloisite 30B, on the biodeterioration of PVC-based nanocomposites plasticized by means of dioctyl adipate (DOA), dioctyl phthalate (DOP) and modified poly(propylene adipate) (PPA), in the aerobic environment of soil (soil burial test, time of exposure: 198 days). Tests were carried out at 25 ± 1 °C, under moisture-controlled (55 %) and aerobic conditions. The extent of the biodeterioration process was evaluated on the basis of changes in weight, tensile strength and elongation-at-break values. Finally, analysing chemical structures using FTIR and visual observation, both macroscopic and microscopic via scanning electron microscopy assisted in the evaluation process. The results of this study suggested that plasticized PVC/montmorillonite nanocomposites have an increased susceptibility for undergoing biological deterioration in comparison with plasticized PVC. In each instance, adding Cloisite 30B resulted in reducing the resistance of PVC/montmorillonite nanocomposites to the actions of microorganisms. In the case of Cloisite Na+ as the filler, results cannot be clearly quantified, although a negative influence prevailed, particularly a change in colour, whose change intensity was also dependent on the type of plasticizer, increasing in the following sequence: PVC/DOA/Cloisite Na+ > PVC/DOP/Cloisite Na+ > PVC/PPA/Cloisite Na+. However, each sample containing Cloisite Na+ achieved a lower rate of degradation (by normalised weight loss and FTIR) compared with nanocomposites containing Cloisite 30B. This can be attributed to the migration and accumulation of Cloisite Na+ on the surface of the nanocomposites particles where the former phenomenon producing a surface barrier which caused a reduction in the permeability of the material toward water and microorganisms, during the test. 相似文献
The linear dynamic viscoelastic properties and non-linear transient rheology of polycarbonate (PC)/clay nanocomposites were investigated at temperatures ranging from 240 to 280 °C. For the study, nanocomposites of PC and natural montmorillonite (Cloisite Na+) or chemically modified clay (Cloisite 30B) were prepared by melt blending in a twin-screw extruder. Cloisite 30B is a natural montmorillonite modified with methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium chloride (MT2EtOH). In both PC/Cloisite Na+ and PC/Cloisite 30B nanocomposites the concentration of clay was varied from 2.3 to 4.3 wt%. In situ Fourier transform infrared (FTIR) spectroscopy results show that at temperatures ranging from 30 to 280 °C the carbonyl groups in PC and the hydroxyl groups in MT2EtOH of Cloisite 30B in PC/Cloisite 30B nanocomposites formed hydrogen bonds, while no evidence of hydrogen bonding was observed in the PC/Cloisite Na+ nanocomposites. There are no discernible sharp reflections in the X-ray diffraction (XRD) patterns of PC/Cloisite 30B nanocomposites, after Cloisite 30B having the d001 spacing of 1.85 nm was mixed with PC, whereas the d001 spacing changes little (1.17 nm) before and after the mixing of Cloisite Na+ to PC. Transmission electron microcopy (TEM) images show that organoclay platelets are well dispersed in PC/Cloisite 30B nanocomposites, while the untreated clay platelets are poorly dispersed in PC/Cloisite Na+ nanocomposites. The observed differences in XRD patterns and TEM images between the two nanocomposite systems are explained by in situ FTIR spectroscopy. The results of rheological measurements (linear dynamic viscoelasticity, non-linear transient shear flow, and steady-state shear flow) support the conclusions drawn from the results of XRD, TEM, and FTIR spectroscopy. 相似文献
In this study the effect of using nanoclay particles in two different matrices on anticorrosive performance improvement of a novel water-based epoxy coating was investigated. For this purpose, Na+-montmorillonite (Na+-MMT) and organo-montmorillonite (Cloisite 30B) were introduced into water-based hardener (RIPI-W.B.H.) and epoxy resin matrices, separately. Nanoclays were added to polymeric matrices using direct mixing under an ultrasonic homogenizer. The coatings were analyzed to ensure the intercalation and distribution of layered silicates by means of X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses. The structure of products is studied by infrared (IR) spectrometer. The corrosion protection performances of the coatings were investigated using salt spray test and electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution. The results showed that using Cloisite 30B in water-based hardener had the best performance and its application in anticorrosion water-based zinc rich epoxy coating approved of it. 相似文献
The influence of unmodified clay, Cloisite Na+ on adhesion between prevulcanized EPDM rubber and unvulcanized EPDM rubber containing nanoclay was investigated using 180° peel test. The rubber showed improvement in peel strength with increasing clay concentration up to 4 phr, beyond which it decreased. A maximum of 51% improvement in peel strength was obtained for 4 phr Cloisite Na+. This was attributed to enhanced tensile strength, monomer friction coefficient, marginal improvement of polarity and micro-roughness of the clay filled rubber. At higher clay loading (8 phr), the peel strength reduced due to formation of boundary layer of Zn-stearate, accelerators and clay on the outermost surface, diffusion of the fewer rubber chains, agglomeration of the clay particles and increased modulus of the rubber. 相似文献
A series of poly(vinyl alcohol)/Cloisite Na+-Tyrosine/Zinc oxide (PVA/Cloisite Na+-Tyr/ZnO) bionanocomposites were prepared by dispersing ZnO nanoparticles in solution containing mixture of the PVA and modified Cloisite Na+. Structure of nanocomposite coatings was investigated by X-ray diffraction and Fourier-transform infrared spectroscopy. The thermal stability and optical properties of bionanocomposite were characterized by thermogravimetric analysis and UV–vis spectroscopy, respectively. The introduction of ZnO nanoparticles into PVA/Cloisite Na+-Tyr mixed solutions significantly increased the thermal stability of the obtained films. The results revealed that the high UV-shielding efficiency of the composites: for a film containing 6.0 wt% of ZnO nanocrystals, over 92% of UV light at wavelengths of 368 nm was absorbed while the optical transparency in the visible region was slightly below that of a PVA/Cloisite Na+-Tyr film. 相似文献
The present study demonstrates the use of a simple and versatile melt-compounding route to prepare NaClO4-containing poly(ethylene oxide) PEO/clay nanocomposites combining excellent mechanical properties with a competitive level of the ionic conductivity. The nanostructure and the resulting thermal, mechanical and conductive properties of the salt-containing PEO/clay nanocomposites were found to be highly sensitive to the clay type, i.e. aspect ratio of the clay, to the presence of an organic modifier in the intergallery spacing, and to the salt concentration. The highest increase of the shear storage modulus is obtained in the presence of single silicate layers, thus an exfoliated nanostructure, having a high aspect ratio. These structures are only obtained with an (polar) organically modified clay (Cloisite 30B), regardless of the presence of salt. The use of non-organically modified clays (Cloisite Na+ and Laponite) resulted in intercalated nanocomposites, with only a minor improvement in stiffness. A strong interaction between the Na+ from NaClO4 and the Cloisite 30B silicate layers might be responsible for an increased PEO crystallinity and resultant additional increase in stiffness. A mechanism is proposed whereby the Na+ ions are drawn away from the PEO phase, to be complexed by the silicate layers, or even ion-exchanged with modifier cations. The addition of clay did not greatly affect the ion conductivity below the melt temperature of PEO. At higher temperatures, the nanocomposites displayed only slightly lower conductivities compared to the PEO/NaClO4 complex, due to the presence of the clay platelets. 相似文献
A series of Na-montmorillonite (Na+-MMT) modified acrylic impact modifiers (mAIM) were prepared by seeded emulsion polymerization. These mAIM modifiers were characterized by XRD. A 0.24?nm of increased interlayer distance of Na+-MMT was an indication of polymer chains intercalation within interlayer spacing. The notched Izod impact tests proved that the impact strength of the PVC/AIM composites prepared by melt blending was 43?J/m, markedly higher than the impact strength of pure PVC. Furthermore, with increasing content of AIM, the composites exhibited changes from brittle fracture to ductile fracture, with the impact strength increasing from 200 to about 1,000?J/m. The impact strength of PVC/mAIM also showed the same trend, although there were drops in some values. The impact strength of PVC/mAIM composites decreased with the increases in Na+-MMT content, but the yield strength and modulus of the composites increased with higher Na+-MMT content. The result also showed that the tensile strength of mAIM with 2 wt?% Na+-MMT is lower than that of mAIM with 0.8 and 1 wt?% contents, but still sufficiently large in comparison to the tensile strength of mAIM with 0 wt?% Na+-MMT. The dynamic mechanical analysis (DMA) result showed that the glass transition temperature (Tg) of mAIM did not show obvious changes and the elasticity of mAIM was reduced with the additional Na+-MMT content. 相似文献
Phenolic resin/clay composites were prepared by high‐shear mixing of clay suspended in CH3OH solutions of Novolac resin and curing agent. Pure clay Cloisite Na+ and pillared clays Cloisite 10A, 30B, and Na+Cloisite that was pillared by 3‐hexadecyl‐1‐methylimidazolium bromide were studied. After CH3OH evaporation, Novolac was cured at low temperatures. XRD showed that clay gallery d‐spacings decreased upon solvent evaporation and partial curing. Slight d‐spacing increases were sometimes observed from a partially cured stage to a further cured composite. Na+Cloisite gave the highest nanodispersion, Cloisites 10A and 30B the lowest. TGA revealed that Na+ clay or organoclay incorporation in partially cured and cured composites did not improve the thermal stability of Novolac.
In this study the inorganic nanolayers of Cloisite Na+ was modified with ammonium salt of l-valine amino acid (Val) and then it was dispersed in poly(vinyl alcohol) (PVA) matrix. The PVA/Cloisite Na+/Val bionanocomposites (BNC)s were prepared by solution intercalation technique using ultrasonic irradiation. The reaction between this novel organically modified Cloisite Na+ and PVA occurred by the hydrogen bonding and hydrophobic interactions. The basal spacing of the Cloisite Na+/Val was studied by X-ray diffraction. The thermal stability and optical clarity of PVA and PVA/Cloisite Na+/Val are also studied by thermogravimetric analysis (TGA) and UV–visible transmission spectra, respectively. TGA results show that using Cloisite Na+/Val in the PVA matrix improved the thermal stability property of the resulting BNC films. The morphological image of synthesized materials was studied by scanning electron microscopy, and transmission electron microscopy. The nanocomposite structure study specified a coexistence of exfoliated and intercalated Cloisite Na+/Val layers in the PVA matrix. 相似文献
This study explains how to make rigid polyurethane/mature fine tailings (PU/MFT) foam composites with good mechanical and thermal properties by in situ polymerization. Compared to PU/Cloisite Na+ and PU/Cloisite 30B composites, the novel PU/MFT composites have similar tensile properties, but better thermal properties. Adding 2 parts per hundred parts (pphp of polyol by weight) of MFT particles decreases the thermal conductivity of polyurethane foam by 10%, while adding Cloisite Na+ or Cloisite 30B decreases it by only 6% and 5%, respectively, resulting in considerable energy savings in large‐scale insulation applications. PU/MFT foams also sustain about the same compressive strength and modulus even when loaded up to 20 pphp MFT. These results are important for oil sands industries trying to decrease the environmental footprint of their operations and for polyurethane‐producing companies attempting to improve properties of their products and contribute to environmental cleanup.
Biodegradable thermoplastic starch (TPS)/clay hybrids were prepared by melt intercalation. Three organically modified montmorillonite (MMT) with different ammonium cations and one unmodified Na+ MMT (Cloisite Na+) were used. Cloisite Na+ showed the best dispersion in the TPS matrix. It was observed that the TPS/Cloisite Na+ hybrid showed an intercalation of TPS in the silicate layer due to the matching of the surface polarity and interactions of the Cloisite Na+ and the TPS, which gives higher tensile strength and better barrier properties to water vapor as compared to the other TPS/organoclay hybrids as well as the pristine TPS. It was found that the dynamic mechanical properties of the TPS/clay hybrids were also affected by the polar interactions. 相似文献
The influence of clay particles on the corrosion properties of bituminous coating was studied. Different percentages of natural montmorillonite clay (Cloisite Na+) were added to emulsified bitumen in water to make 2 wt.%, 3 wt.% and 4 wt.% of clay/bitumen nanocomposite coatings. The coatings were applied on steel 37. Optical microscopy and transmission electron microscopy (TEM) were employed to study the structure of nanocomposite. To investigate the anti-corrosion properties of the coated panels, electrochemical impedance spectroscopy (EIS) was used. The findings indicated that the addition of clay nanolayers improved corrosion resistance of the coatings. Moreover, increasing clay loading up to 4 wt.%, increased the corrosion resistance. 相似文献