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In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide), modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr.

BACKGROUND: In this study, we have fabricated a polymeric material (CNC/Im) consisting of cellulose nanocrystals (CNC) synthesized from Vietnamese rice husk biomass and imidazole (Im) dopant. Next, we propose a new approach to fabricate Nafion/CNC/imidazole (NCI) composite materials by mixing the CNC/imidazole hybrid into Nafion matrix using a very simple solution method, and then investigating the influence of CNC/Im on the properties of NCI membranes. RESULTS: Electrochemical impedance spectroscopy (EIS) analysis showed that the proton conductivity of the CNC/Im membrane depends on the linked molar ratio of Im to glucose units (denoted by the n index), and this value is higher than that of pure CNC by a factor of 6. Differential thermal analysis (DSC) showed that the value of the n index is around 1:17 with all the content ratios between CNC and Im. Next, we synthesized composite materials based on CNC/Im and Nafion 117 (NCI) and investigated the influence of CNC/Im on the properties of NCI membranes. The results demonstrated that proton conductivity of the NCI membranes changes according to the content of Nafion 117, and reaches the highest value of 6.19 × 10 −4 S m -1 with an Nafion 117/(CNC/Im) ratio of 2:1. It was observed that the CNC fiber bundles were surrounded by a polymer layer and no phase separation occurs in the scanning electron micrographs of NCI materials.CONCLUSIONS: These results indicate that the prepared NCI composites will be potential materials for eco-friendly fuel cell operating in low humidity conditions.

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Nanohybrids of zinc oxide/cellulose nanocrystals (ZnO/CNCs) were successfully prepared by using a low cost and green method for adsorption and photocatalytic degradation of methylene blue (MB). CNCs have been derived through the hydrolysis reaction by citric/hydrochloric acid from the pure cellulose isolated from Vietnamese Nypa fruticans trunk. The influence of the Zn2+ ion concentration on the morphology, microstructure, and thermal properties as well as the photocatalytic activity of the ZnO/CNC nanohybrids was investigated in detail. Analyses of FTIR spectra, XRD, and SEM indicated that the ZnO nanocrystals with the size of 50 nm formed and loaded on the surface of CNC. Based on the DRS spectra and the nitrogen adsorption–desorption isotherms (BET) analysis, the absorption of ultraviolet light with a strong absorption band around 400 nm was found for all the ZnO/CNC nanohybrids, and the values of specific surface areas (SBET) of materials can be controlled by changing the concentration ratio of Zn2+ ion and CNC. The TGA analysis demonstrated that the ZnO loading samples (ZnO/CNC) had the thermal degradation onset temperature higher than that of neat CNC. The effect of MB removal showed the results which were contributed not only by the adsorption ability of CNC but also by the photocatalytic activity of ZnO. The photocatalytic efficiency significantly depended on the content of ZnO loading. The maximum degradation of MB was about 95% in 150 min for the ZnO/CNC-1.0 sample in which the concentration ratio of zinc-precursor Zn(NO3)2·6H2O and CNC was 1.0.

Heavy metals are known to be toxic, even at low content (ppm), for living organisms[1,2]. The presence of heavy metals and other pollutants in water continues to be a major concern and the removal of such contaminants is considered as an important solution for environmental remediation[3,4]. In this paper, we study the ability adsorption of  Pb2+ and Cd2+ heavy ionic metal on silica nanomaterials which was extracted and purified from Vietnamese rice husk. The structure of the materials was investigated by X-ray diffraction (XRD) and FT-IR spectroscopy. By Adsorption Atomic Spectroscopy (AAS) analysis, the results have demonstrated the time taken for attaining equilibrium adsorption is about 1.5 hours for both cases, and the adsorption capacity of Pb2+ and Cd2+ on silica are 21 and 24 mg/L, respectively.

A new method to separate graphite oxide (GO) modified by polyethylene oxide (PEO) by the aid of ultrasonic radiation was developed. Modified GO (graphene oxide or single layer of graphite oxide) did not show not appear crystalline peak (d002) on the X-Ray and took the form of a single layer graphene oxide on the image AFM and TEM. The exfoliated graphene oxide was reduced (RGO) to graphene by the reducing agent system HI – Acetic acid (HI-AcOH). The sheet resistance of RGOHI-AcOH is about 120 Ω/sq in the form graphene paper. In addition, FTIR, UV-Vis and Raman spectra showed more clearly about characteristics of graphite oxide, graphene oxide and RGOHI-AcOH.

In this study, we focused was on the determination of amylose and amylopectin components of starch from different plant sources in Vietnam by UV-VIS spectroscopy. Besides, the distribution of natural starch structure and crystallization level of different starches was also evaluated by FT-IR, XRD analysis methods. By UV-VIS absorption spectroscopy, we could quantify amylose and amylopectin contents which are the two main components in different starch sources in Vietnam. Our results have showed that corn starch sample had the highest amylose content at 28.22%wt. The degree of morphology in the structure is evaluated through FT-IR spectroscopy method and the crystallization ability of starch was determined by XRD diffraction method. These results showed that although the amylose content of arrowroot starch sample (27.24%) is higher than that of cassava starch (10.31%) or rice starch samples (17.10%), but the tightness rearrange level in the structure of dong starch is the smallest (0.2089) compared to cassava starch (0.2793) or rice starch (0.6645). After all these effective results, starch sample having the good properties and degree of crystallization as well as suitable amylose pectine content will be selected to for further plasticization and modification for the application in elaboration of biodegradable starch based composite materials.