Studies on wettability of polypropylene/methyl-silicone composite film and polypropylene monolithic material

A polypropylene/methyl-silicone superhydrophobic surface was prepared using a simple casting method. Varying the ratio of polypropylene and methyl-silicone results in different surface microstructure. The wetting behavior of the as-prepared surface was investigated. A polypropylene monolithic material was also prepared. Its superhydrophobicity still retains when the material was cut or abraded. The as-prepared material can also be used to separate some organic solvents from water.     

A new technique for preparing macroporous inorganic composite material

Macroporous CdS/SiO₂ was prepared with a new approach in which at first CdS nanoparticles were deposited on polymer microbeads without surfactant, then core-shell composite was self-assembled with sedimentation-aggregation, and at last macroporous material was obtained by the removal of the template. The results show that the morphology of core-shell composite could be tailored by the polymer template and the concentration of the reactant, and the shell thickness could be altered by the temperature and the aging time. This new idea was an effective method to prepare other macroporous composite with large-scale.     

A study of the optical properties of polypropylene based polymer composite films

The optical clarity of the polymeric material can be influenced by changing the preparations parameters and thus the polymer structure. In this study, the transmittance, absorptance and reflectance of the polypropylene (PP) based polymer composites, synthesized by pressing method, changing the thickness between 8 — 29 μm, are investigated. Infrared and ultraviolet spectra of PP/diamond and PP/fiber composite in the wavelength range 200–25000 nm are examined. Optical absorption spectra recorded in the UV-Visible range are presented; the determined values of energy gaps are listed. The results indicate that both mechanism, direct and indirect transitions may exist. The analysis of absorption peaks corresponding to oxygen groups, for PP/diamond (0.3–0.5 %) and PP/fiber (20–30 %) composites, show low optical densities which complies with our other studies.     

Gas transport properties of polypropylene/clay composite membranes

Polypropylene membranes modified with natural and organically modified montmorillonite clays were prepared. The permeability, diffusivity and solubility of helium, oxygen and nitrogen were determined for the unfilled and filled membranes over the temperature range 25-65 °C. Physical properties of polypropylene membranes were investigated using X-ray diffraction, thermogravimetric analyser, tensile testing and differential scanning calorimetry. The results showed that the filled membranes exhibit lower gas permeability compared to the unfilled polypropylene membrane. For helium, a reduced diffusivity is mainly responsible for the reduction in the permeability, in contrast, for nitrogen and oxygen, both diffusivity and solubility were reduced by the presence of fillers. The X-ray diffraction spectra showed that the incorporation of the unmodified and modified clay did not affect the crystallographic nature of polypropylene.     

A carbon-silica composite material based on powdered cellulose: Synthesis and properties

A procedure was developed for preparing a carbon-silica composite by thermolysis of powdered cellulose in the presence of tetraethoxysilane. The resulting composite was studied in model processes of trimethylhydroquinone oxidation and hydrogen peroxide decomposition.     

Microstructure and mechanical properties of isotactic polypropylene composite with two‐scale reinforcement

Isotactic polypropylene (iPP) composite with two‐scale reinforcement structure, i.e. nanoscale shish–kebab structure and micron‐scale glass fiber (GF) with orientation, was fabricated by an oscillatory shear injection molding (OSIM) technology. The oscillatory shear flow provided by the OSIM gave rise to a high fraction of shish–kebab structures in the iPP composite, characterized by X‐ray scattering technique. On the other hand, the oscillatory shear flow oriented GFs in the iPP composite, which was revealed by scanning electron microscopy measurement. The iPP composite with this two‐scale reinforcement structure exhibited simultaneously remarkably enhanced tensile strength and impact strength. Fracture mechanism of this iPP composite was also proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

A new unusual natural pigment from Selaginella sinensis and its noticeable physicochemical properties

A new unusual pigment with a novel carbon framework named selaginellin (1) was isolated from the acetone extract of Selaginella sinensis, and its methoxy derivative (1a) was synthesized. Both selaginellin 1 and 1a are racemic compounds. The structure of selaginellin 1 was established as (R,S)-4-[(4'-hydroxy-4-(hydroxymethyl)-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene]-2,5-cyclohexadien-1-one and 1a as (R,S)-4-[(4'-methoxy-4-(methoxymethyl)-3-((4-methoxyphenyl)ethynyl)biphenyl-2-yl)(4-methoxyphenyl)methylene]-2,5-cyclohexadien-1-one by the analysis of one- and two-dimensional NMR data, HR-ESIMS, EI-MS, IR, UV, CD, and single-crystal X-ray experiments, and the mechanism of their color change according to different pH values and fluorescent properties was studied.     

Synthesis and physicochemical properties of new fluorescent derivatives of cytosine

Sixteen new fluorescent N⁴‐(E)‐stilbenyloxyalkylcarbonyl‐cytosines 9–16 and N⁴‐(E)‐stilbenyloxyalkylcarbonyl‐1‐methylcytosines 17–24 have been synthesized. The differences in ¹H and ¹³C NMR spectra in two solvents (DMSO and TFA) have been pointed out and discussed. Assignment of the signals in the spectra of the compounds 9–24 in NMR in DMSO‐d₆ solutions has been made the basis of the homonuclear (COSY) and heteronuclear (HETCOR) spectra. The effect of the substituent (Cl, Br, NO₂) on the stilbene moiety on the fluorescence spectrum of each compound has been discussed.     

Recycled polypropylene with improved thermal stability and melt processability

Journal of Thermal Analysis and Calorimetry - Polypropylene (PP) is a versatile polymer, with a wide range of applications, from household appliances to packaging and automotive components....     

A new polymer/clay nano-composite hydrogel with improved response rate and tensile mechanical properties

A new type of stimuli-responsive organic/inorganic nano-composite hydrogel was prepared by introducing fibrillar attapulgite into poly(2-hydroxyethyl methacrylate-co-poly(ethylene glycol) methyl ether methacrylate-co-methacrylic acid) network, in which the nanosized attapulgite fibril worked as the cross-linker instead of conventional chemical cross-linker. In the preparation process, a prepolymerization route was adopted to effectively stabilize the dispersion of attapulgite. The structure and morphology of the nano-composite hydrogels were characterized by SEM, FTIR and DSC. The swelling/deswelling behaviors and tensile mechanical properties of the nano-composite hydrogels were compared with that of the corresponding chemically cross-linked hydrogel. The results showed that the nano-composite hydrogels had much greater equilibrium-swelling ratio, much faster response rate to pH and significantly improved tensile mechanical properties. As the content of AT increased, the tensile strength, effective cross-link chain density and glass transition temperature increased, while the equilibrium swelling ratio, deswelling rate and elongation at break decreased.     

Vibration-induced change of crystal structure in isotactic polypropylene and its improved mechanical properties

In order to understand the formation of different crystal structures and improve the mechanical properties of isotactic polypropylene (iPP), melt vibration technology, which generally includes shear vibration and hydrostatic pressure vibration, was used to induce the change of crystal structure of iPP. iPP forms α crystal structure in traditional injection molding. Through melt vibration, crystal orientated and its size became smaller, and a change of crystal structure of iPP from α form to β form and γ form was achieved. Therefore, the mechanical properties of iPP were improved. At high melting temperature (230 °C), only β form can be induced. At low melting temperature (190 °C), either β form or γ form can be induced, depending on the combination of frequency and vibration pressure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2385–2390, 2004     

Comprehensive assessment of physicochemical properties of new energetic materials

The review presents original methodological approaches and summarizes the results of research into the assessment of relationships between the structure of energetic organic compounds and their main physicochemical properties. A large number of experimental values of these parameters were statistically analyzed, and a database of the properties of explosives and rocket propellant ingredients was created. Based on the analysis and integration of these data, approaches were developed to evaluate the fundamental properties of energetic compounds of different chemical classes, such as the enthalpy of formation, the molecular crystal density, and the sensitivity to mechanical impacts. The explosive and ballistic characteristics were calculated. The comprehensive assessment was made of the possible applications of new substances and those poorly characterized by experimental methods.     

A structural polymeric composite material reinforced with basalt fiber

A process was developed for preparing a polymeric composite material by combining the synthesis of the oligomer with its reinforcement with basalt fiber. The advantage of this process relative to the traditional technology is more efficient interaction of the oligomer with the basalt fibers, positively affecting the composite formation and ensuring improved physicochemical and mechanical properties of the basalt-reinforced plastics.     

Facile and green solvothermal synthesis of palladium nanoparticle-nanodiamond-graphene oxide material with improved bifunctional catalytic properties

We developed a selective solvothermal synthesis of palladium nanoparticles on nanodiamond (ND)–graphene oxide (GO) hybrid material in solution. After the GO and ND materials have been added in PdCl₂ solution, the spontaneous redox reaction between the ND–GO and PdCl₂ led to the creation of nanohybrid Pd@ND@GO material. The resulting Pd@ND@GO material was characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectrometry, scanning electronic microscopy (SEM), and atomic absorption spectrometry methods. The Pd@ND@GO material has been used for the first time as a catalyst for the reduction for 2-nitrophenol and the degradation of methylene blue in the presence of NaBH₄. GO plays the role of 2D support material for Pd nanoparticles, while NDs act as a nanospacer for partly preventing the re-stacking of the GO. The Pd@ND@GO material can lead to high catalytic activity for the reduction reaction of 2-nitrophenol and degradation of methylene blue with 100% conversion within ~15 s for these two reactions even when the content of Pd in it is as low as 4.6 wt%.     

Preparation of ZnO/GO composite material with highly photocatalytic performance via an improved two-step method

ZnO/graphene oxide(ZnO/GO) composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange(MO) under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.     

Bacterial cellulose-MMTs nanoreinforced composite films: novel wound dressing material with antibacterial properties

This study was conducted to develop nanocomposite films of bacterial cellulose (BC) and montmorillonite (MMT) with potent antibacterial activity and potential therapeutic value in wound healing and tissue regeneration. Different composites were prepared through impregnation of BC sheets with 2 and 4 % suspensions of MMT, Na-MMT, Ca-MMT and Cu-MMT. These modified MMTs were prepared through cation exchange strategy. The antibacterial activities of the composites were then assessed against Escherichia coli and Staphylococcus aureus through the disc diffusion assay and colony forming unit (CFU) count methods. BC-Cu-MMT composites prepared with 2 and 4 % MMT displayed clear zones of inhibition against E. coli (20 and 22 mm, respectively) and S. aureus (19 and 20.5 mm, respectively). The untainted BC, BC-MMT, BC-Na-MMT and BC-Ca-MMT did not show clear inhibitory zones against the tested organisms. The reduction in CFU observed following treatment with BC-MMTs (BC-MMT, BC-Na-MMT, BC-Ca-MMT and BC-Cu-MMT) prepared using 2 % MMTs suspension was 7.39, 14.8, 19.2 and 77.9 % for E. coli and 6.8, 13.7, 17.4 and 74.1 %, for S. aureus, respectively. When treated with BC-MMT, BC-Na-MMT, BC-Ca-MMT and BC-Cu-MMT prepared with 4 % MMTs suspension, the reduction in CFU increased to 10.58, 18.37, 24.62 and 85.01 % for E. coli and 9.44, 15.73, 20.40 and 79.79 % for S. aureus, respectively. The outcome of this study will facilitate the development of BC sheets as wound dressings and regeneration materials with antibacterial properties for therapeutic applications without any side effects.     

SnO2 sheet/graphite composite as anode material with improved electrochemical performance for lithium-ion batteries

The SnO₂ sheet/graphite composite was synthesized by a hydrothermal method for high-capacity lithium storage. The microstructures of products were characterized by XRD and FE-SEM. The electrochemical performance of SnO₂ sheet/graphite composite was measured by galvanostatic charge/discharge cycling and EIS. The first discharge and charge capacities are 1,072 and 735 mAh g^?1 with coulombic efficiency of 68.6 %. After 40 cycles, the reversible discharge capacity is still maintained at 477 mAh g^?1. The results show that the SnO₂ sheet/graphite composite displays superior Li-battery performance with large reversible capacity and good cyclic performance.     

Changes in physicochemical and mechanical properties of γ-irradiated polypropylene syringes as a function of irradiation dose

The effect of γ-irradiation on mechanical, thermal, physicochemical and structural properties of polypropylene (PP) syringes was studied. Irradiation doses of 30, 60 and 120 kGy were used with non-irradiated PP syringes serving as control samples. Irradiation caused a significant deterioration in mechanical properties of samples. The compression strength of whole syringe body decreased with increasing irradiation dose. Similarly % extension at break decreased with increasing irradiation dose. Of the physicochemical properties tested, both degree of yellowness and extractable radiolysis products increased with increasing irradiation dose. Melting temperature as well as specific melting enthalpy decreased with increasing irradiation dose. Minor differences in FTIR spectra were observed, mainly in the region of 1720 cm⁻¹, corresponding to the absorption of carbonyl compounds indicating the formation of increased amounts of oxidation products at high irradiation doses. Gas chromatography- mass spectroscopy analysis indicated the formation of a number of radiolysis compounds as a result of irradiation. The number and concentration of these compounds increase progressively with increasing dose until 60 kGy. At the same time a number of compounds initially present in non-irradiated syringes were destroyed by irradiation.     

Changes in physicochemical and mechanical properties of electron-beam irradiated polypropylene syringes as a function of irradiation dose

In the present study, the effect of electron-beam irradiation on physicochemical and mechanical properties of polypropylene (PP) syringes was studied. Three irradiation doses (30, 60 and 120 kGy) were applied to all samples. Non-irradiated PP syringes were used as control samples. Electron-beam irradiation caused an increase in the degree of yellowness and in the extractable radiolysis products. A decrease in compression strength and extension at break was the result of electron-beam irradiation on mechanical properties of PP syringes. Minor differences were observed in FTIR spectra, mainly in the region of 1720 cm⁻¹, corresponding to the absorption of carbonyl compounds. Gas chromatography/mass spectrometry (GC/MS) analysis indicated the formation of a number of radiolysis compounds while a number of compounds initially present in non-irradiated syringes were destroyed by the irradiation. The degradation on polymer properties caused by electron-beam irradiation was less severe than that caused by gamma irradiation.