ABSTRACT Saponite (SA)-mercaptopropyl polyhedral oligomeric silsesquioxane (POSS-SH) grafted poly (L-lactic acid) (SA-POSS-PLLA) was synthesized by thiol-ene click chemistry. SA-POSS-PLLA was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. When 0.3 wt% SA-POSS-PLLA was used as a modifier in poly (lactic acid) (PLA), the impact strength and elongation at break of PLA/SA-POSS-PLLA nanocomposites were increased by 1.73 times and 4.25 times compared with pure PLA, respectively. The differential scanning calorimeter analysis showed that the crystallinity of PLA/SA-POSS-PLLA nanocomposites was increased from 7.74% to 30.32%. The addition of SA-POSS-PLLA increased the crystallization rate of PLA and significantly reduced the grain size of PLA, which also was proved by polarization optical microscopy analysis. Rheonaut technology for simultaneous rheometry and FTIR demonstrated that the reason why the addition of SA-POSS-PLLA nanoparticles accelerated the crystallization rate of PLA was that SA-POSS-PLLA nanoparticles promoted the adjustment of C-O-C structure and -CH3 group in the main molecular chain of PLA.

The physical, chemical and gemological properties of recently discovered common green opals from Anosy (South-Eastern Madagascar) have been investigated using different analytical methods such as standard optical and gemological analyzes, X-ray powder diffraction (XRPD), Scanning Electron Microscopy (SEM), Micro-Raman Spectroscopy and Laser Ablation Microprobe (LA-ICP-MS). Anosy opals have a yellowish green color with a light yellowish rim, translucent / opaque diaphaneity with greasy luster, red oxide spots and are inert to long and short wavelength UV radiation (366–254 nm). The values for refractive index and specific gravity range between 1.435–1.460 and 2.03-2.07, respectively. According to XRPD and Raman analyses, the opals are CT type with tridymite more abundant than cristobalite and also contain clay minerals (saponite). Iron and, subordinately, V and Cu appear the main chromophores that determine the green-yellowish color, while Ni and Cr are very subordinate. Other detected trace elements are Mg, Al, Ca, K, and Na. The high contents of Ba are noteworthy since this element is rarely reported in opals worldwide. SEM observations show three types of structures already observed in the CT opals: homogeneous and very fine microspheres, lepispheric cauliflower structures and globular aggregates of different sizes formed by laminae.

Decontamination of radioactive hazardous materials by using novel biodegradable strippable coatings and new generation complexing agents

Saponite-anthocyanin pigments: Slipping between the sheets

Bioavailability of clay-adsorbed dioxin to Sphingomonas wittichii RW1 and its associated genome-wide shifts in gene expression

Poly(vinyl alcohol) (PVA) nanocomposites containing three different nanofillers are prepared and compared in terms of their thermal properties, morphologies, and oxygen permeabilities. Specifically, pristine saponite (SPT) clay, hydrophilic organically modified bentonite (OMB), and hexadecylamine-functionalized graphene sheets (HDA-GSs) are utilized as nanofillers to fabricate PVA nanocomposite films. The hybrid films are fabricated from blended solutions of PVA and the three different nanofillers. The content of each filler with respect to PVA is varied from 0 to 10 wt%, and the changes in the properties of the PVA matrices as a function of the filler content are discussed. With respect to the hybrid containing 5 wt% of SPT, OMB, and HDA-GS, each layer in the polymer matrix consists of well-dispersed individual nanofiller layers. However, the fillers are mainly aggregated in the polymer matrix in a manner similar to the case for the hybrid material containing 10 wt% of fillers. In the thermal properties, SPT and OMB are most effective when the filler corresponds to 5 wt% and 7 wt% for HDA-GS, respectively, and the gas barrier is most effective with respect to 5 wt% content in all fillers. Among the three types of nanofillers that are investigated, OMB exhibits optimal results in terms of thermal stability and the gas barrier effect.

Morphologies, thermo-optical properties, and gas barriers of poly(vinyl alcohol) (PVA) hybrid films containing two different clays are compared. Saponite (SPT) and hydrophilic bentonite (BTT) were used as the reinforcing filler in the fabrication of PVA hybrid films, which were synthesized from aqueous solutions and were solvent-cast at room temperature under vacuum, yielding 20-31-μm-thick PVA hybrid films with varying clay contents. The addition of small amounts of clay is sufficient to improve the thermal properties and gas barriers of PVA hybrid films. Even polymers with a low clay content (3-10 wt%) were found to exhibit much higher transition temperature values than pure PVA. The addition of BTT was more effective than the addition of SPT for improving the thermal properties and gas barrier in the PVA matrix. The PVA hybrid films containing 5 wt% SPT were equibiaxially stretched, with stretching ratios ranging from 150% to 250%. Clay dispersion, morphology, optical transparency, and gas permeability were then examined as a function of the equibiaxial stretching ratio. PVA hybrid films with a stretching ratio of ≥ 150% displayed homogeneously dispersed clay within the polymer matrix and exfoliated nanocomposites.

Poly(amic acid) (PAA) was prepared by the reaction of 4,4′-(hexafluoro isopropylidene) diphthalic anhydride with 2,2′-bis(trifluoromethyl) benzidine in N, N-dimethylacetamide. Hybrid films were obtained from blended solutions of the precursor polymer and saponite (SPT) or organically modified hectorite (STN) clays, and the clay content was varied from 0 to 40 wt%. The cast film of PAA was heat treated at different temperatures to create polyimide (PI) hybrid films. The nanostructure of the hybrid films was observed using transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. The addition of SPT was more effective than the addition of STN with regard to improving the thermal properties, whereas the addition of STN was more effective with regard to improving the optical transparency and gas barrier characteristics of the PI matrix.

용액 삽입법을 이용하여 다양한 함량의 사포나이트(SPT) 점토를 포함한 폴리(비닐 알코올)(poly(vinyl alcohol), PVA) 나노 복합체 필름을 제조하였다. SPT를 0에서 10 wt%까지 첨가한 PVA 나노 복합체 필름들의 열적 특성, 모폴로지, 광학 투명성 및 기체 투과성에 대해 조사하였다. 특히 5 wt% SPT 포함한 PVA 복합체 필름이 매우 우수한 열적 특성과 기체 차단성을 나타내었다. 5 wt% SPT 포함된 복합체 필름을 연신율에 따라 150에서 250%까지 이축 연신하였고, 이축 연신율에 따른 점토 분산성, 광학적 특성 및 기체 투과성에 대한 조사를 하였다. 다양한 비로 이축 연신한 PVA 나노 복합체 필름은 우수한 광학 투명성과 산소 차단성을 보였다. Poly(vinyl alcohol)(PVA) nanocomposite films containing various saponite (SPT) clay contents were synthesized using a solution intercalation method. The thermal property, morphology, optical transparency, and gas permeability of the PVA nanocomposite films with various SPT contents in the range of 0 to 10 wt% were examined. PVA nanocomposite film containing 5 wt% SPT showed excellent thermal and gas barrier property. The hybrid films containing 5 wt% SPT were equibiaxially stretched with stretching ratios ranging from 150 to 250%. The clay dispersion, optical transparency, and gas permeability were also examined as a function of equibiaxial stretching ratio. The PVA nanocomposite films with various equibiaxial stretching ratios showed excellent optical transparency and barrier to oxygen permeability.

Clay hybrid films were obtained by the solution blending of saponite (SPT) with various amounts of poly(vinyl alcohol) (PVA). Variations in the thermal properties, morphology, optical transparency, and gas permeability of the clay hybrid films with PVA content in the range 0–10 wt% were examined. With increasing PVA content, the thermal transition temperatures of the hybrids decreased. However, the values of the coefficient of thermal expansion (CTE) increased gradually. The values of the yellow index (YI) and oxygen transmission rate (O2TR) of the clay hybrid films remained constant regardless of their PVA content. Open image in new window

The enhancement of barrier properties in composites depends on several factors such as the quantity, length, and width of the clay particles, as well as their orientation and dispersion. Numerous studies have shown that the aspect ratio of exfoliated clay particles plays a critical role in controlling the microstructure of polymer-clay nanocomposites and their gas barrier performance. Although polymer-clay nanocomposites have displayed enhanced gas barrier properties relative to conventional composite systems, the dependence of these properties on factors such as the extent of clay aggregation and dispersion is not well understood. There are many types of clays, including kaolinite, montmorillonite, hectorite, saponite, synthetic mica, and so on. Among these, saponite (SPT) consists of stacked silicate layers with lengths of about 160-170 nm. The thickness of these layers is the same, i.e., 1 nm. SPT has a high swelling capacity, which is essential for efficient intercalation of a polymer, and its stacked silicate layers provide good thermal, tensile, and molecular barrier properties, as do its hybrid polymer-containing materials. SPT has been used widely as a reinforcing filler in polymeric matrices because of its excellent mechanical, electrical, and thermal properties, and its low price. Poly(vinyl alcohol) (PVA) is a water-soluble polymer that is extensively used in paper coatings, textile sizing, and the production of flexible water-soluble packaging film. Such applications have stimulated interest in improving the mechanical, thermal, and permeability properties of thin nanocomposite films while retaining the optical clarity of PVA. PVA nanocomposite materials may offer a viable alternative to heat-treated or conventionally filled PVA materials in commercial applications. In our previous study, the variations in the dispersion, morphology, and gas permeability of nanocomposites with clay contents in the range 0 to 10 wt% were examined. For clay loadings up to 5 wt%, the clay particles were found to be highly dispersed in the PVA matrix without agglomeration of the particles. However, some agglomerated structures formed in the polymer matrix above 7 wt% SPT. In this paper, we report the optical transparency and the oxygen transmittance rate (O2TR) in PVA hybrid films containing 5 wt% SPT. The resulting optical transparencies and gas barrier properties are discussed in terms of the relative equibiaxial stretching ratios (150% to 300%) in the PVA hybrid films.

Poly(vinyl alcohol) (PVA) hybrid films containing 5 wt% pristine clay mineral were synthesized in the water solution. The various PVA hybrid films were synthesized from structurally different pristine clays: saponite (SPT), montmorillonite (MMT), hectorite (SWN), hydrophilic bentonite (PGV), and mica (Mica). The thermo-optical properties and morphologies of the PVA hybrid films were evaluated with various pristine clays. The nanostructure of the hybrid films was observed using transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. The addition of pristine clay was more effective with regard to improving the thermal properties and gas barrier characteristics, whereas the optical transparency of the PVA hybrid films deteriorated with pristine clay.

Poly(amic acid) (PAA) was prepared by the reaction of 4,4-(hexafluoroisopropylidene)diphthalic anhydride with m-xylylenediamine in N,N-dimethylacetamide. Hybrid films were obtained from solutions of the precursor polymer blended with varying amounts of pristine saponite (SPT) clay (0–25 wt%). The cast PAA film was heat-treated at different temperatures to create polyimide (PI) hybrid films, which showed excellent optical transparencies and were almost colorless. The wide-angle X-ray diffraction and transmittance electron microscopy results for the PI hybrid films showed a substantial increase in the agglomeration of the clay particles as the clay loading was increased from 10–25 wt%. This finding suggests that in hybrid materials with low clay contents, the clay particles are better dispersed in the matrix polymer and do not agglomerate significantly. The addition of some amount of clay was sufficient to improve the thermal and oxygen barrier properties of the PI, with a maximum improvement observed at 20 wt% SPT. Open image in new window

Na+-사포나이트(saponite, SPT) 필름의 유연성을 향상시키기 위해 수용성 고분자인 폴리(비닐 알코올)(poly(vinyl alcohol); PVA)을 다양한 함량(0~10 wt%)으로 사용하여 용액 삽입방법을 통해 SPT 하이브리드 필름을 제조하였다. 본 논문에서는 SPT 하이브리드 필름의 열적·광학적 성질, 모폴로지, 및 가스 투과성 등을 조사하였다. PVA 농도에 따른 SPT 하이브리드 필름의 성질들은 X-선 회절도(XRD), 전계방사형 주사전자현미경(FE-SEM), 시차주사 열량계(DSC), 열중량 분석기(TGA), 열기계 분석기(TMA), 자외선-가시광선(UV-vis.) 흡광도기, 및 산소투과(O2TR) 측정기 등을 통해 조사하였다. SPT 하이브리드 필름의 성질들은 PVA의 무게% 농도에 따라 많은 영향을 받았으며, 적은 양의 PVA도 SPT 하이브리드 필름의 유연성을 증가시키기에 충분하였다.

Abstract Polyimide (PI)/clay hybrids were synthesized using the in situ solution intercalation method via poly(amic acid). The Na ion‐exchanged clays Na + ‐saponite (SPT), Na + ‐mica (Mica), and Na + ‐montmorillonite (MMT) were used for the intercalation of PI polymer chains. Our dispersion results show that pristine SPT is more easily dispersed in a PI matrix than MMT or Mica. PI nanocomposites were prepared with various SPT contents to examine the variations with SPT content in the range 0–1 wt% of the thermomechanical properties, morphology, and optical transparency of the nanocomposites. The PI films have excellent optical transparencies, and are almost colorless. However, the optical transparency of the PI hybrid films decreases slightly with increases in the clay content. We also examined the relationship between the properties and clay content of the PI hybrid films using wide‐angle X‐ray diffraction (XRD) measurements, electronic microscopy (SEM and TEM), and universal tensile machine (UTM). The color intensities of the PI films were evaluated with a spectrophotometer. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Synthesis of aluminium pillared smectite from two raw clays, saponite and Indonesian montmorillonite, has been investigated. The clays were characterized by XRD, N2 adsorption isotherm, DTA-TGA, surface acidity measurements using pyridine-FTIR method, and evaluated for catalytic esterification reaction. The characterization indicated an increase in d001 by metal oxide pillar, increase in BET specific surface area, and surface acidity. DTA-curves showed exothermic peaks in the range of 100-130oC and 400-800oC. TGA curves showed an increase in thermal stability of pillared clays. For both kinds of clays, it was also observed that pillarization reduced weight loss at high temperature. Esterification reaction rate constant and surface acidity data showed that the Bronsted acidity dominantly affects the reaction mechanism compared with the effect of specific surface area and Lewis acid site. Montmorillonite and pillared montmorillonite exhibited higher catalytic activity than saponite and pillared saponite although the specific surface areas of the latter are higher.

Abstract Poly(vinyl alcohol) (PVA)/clay nanocomposites were synthesized using the solution intercalation method. Na ion‐exchanged clays [Na+–saponite (SPT) and Na+–montmorillonite (MMT)] and alkyl ammonium ion‐exchanged clays (C12–MMT and C12OOH–MMT) were used for the PVA nanocomposites. From the morphological studies, the Na ion‐exchanged clay is more easily dispersed in a PVA matrix than is the alkyl ammonium ion‐exchanged clay. Attempts were also made to improve both the thermal stabilities and the tensile properties of PVA/clay nanocomposite films, and it was found that the addition of only a small amount of clay was sufficient for that purpose. Both the ultimate tensile strength and the initial modulus for the nanocomposites increased gradually with clay loading up to 8 wt %. In C12OOH–MMT, the maximum enhancement of the ultimate tensile strength and the initial modulus for the nanocomposites was observed for blends containing 6 wt % organoclay. Na ion‐exchanged clays have higher tensile strengths than those of organic alkyl‐exchanged clays in PVA nanocomposites films. On the other hand, organic alkyl‐exchanged clays have initial moduli that are better than those of Na ion‐exchanged clays. Overall, the content of clay particles in the polymer matrix affect both the thermal stability and the tensile properties of the polymer/clay nanocomposites. However, a change in thermal stability with clay was not significant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3208–3214, 2003

Reduction of Fe(III) in a High-Iron Saponite. Pillaring of the Reduced Samples with Al13 Oligomers

Heat treatment of polyfurfuryl alcohol prepared between taeniolite lamellae

Polyfurfuryl alcohol (PFA) was carbonized between the lamellae of saponite (SAPO) clay which has a structure similar to montmorillonite. The carbon thus obtained was characterized and compared with the carbon previously prepared from (MONT). The carbon from SAPO is quite different from the MONT-carbon; i. e., the former is non-graphitizable and swells with organic solvents. The SAPOcarbon consists of very thin and wrinkled films. Such a unique structure of this carbon comes from three-dimensionally random structure of SAPO template. It was found that the presence of both the unique structure and surface oxygen-containing complexes on the carbon is necessary for the swelling with solvents.