Fabrication of transparent polymer-matrix nanocomposites with enhanced mechanical properties from chemically modified ZrO<Subscript>2</Subscript> nanoparticles

Optically transparent nanocomposites with enhanced mechanical properties were fabricated using stable dispersions of sub 10 nm ZrO₂ nanoparticles. The ZrO₂ dispersions were mixed with a commercially available bisphenol-A-based epoxy resin (RIMR 135i) and cured with a mixture of two amine-based curing agents (RIMH 134 and RIMH 137) after complete solvent removal. The colloidal dispersions of ZrO₂ nanoparticles, synthesized through a non-aqueous approach, were obtained through a chemical modification of the ZrO₂ nanoparticle surface, employing different organic ligands through simple mixing at room temperature. Successful binding of the ligands to the surface was studied utilizing ATR–FT-IR and thermogravimetric analysis. The homogeneous distribution of the nanoparticles within the matrix was proven by SAXS and the observed high optical transmittance for ZrO₂ contents of up to 8 wt%. Nanocomposites with a ZrO₂ content of only 2 wt% showed a significant enhancement of the mechanical properties, e.g., an increase of the tensile strength and Young’s modulus by up to 11.9 and 12.5%, respectively. Also the effect of different surface bound ligands on the mechanical properties is discussed.     

Calculation of Excitation Function of Some Structural Fusion Material for (n, p) Reactions up to 25 MeV

Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, Furthermore, there are not radioactive nuclear waste problems in the fusion reactors. In this study, (n, p) reactions for some structural fusion materials such as ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn and ⁵⁶Fe have been investigated. The new calculations on the excitation functions of ²⁷ Al(n, p) ²⁷ Mg, ⁵¹ V(n, p) ⁵¹ Ti, ⁵² Cr(n, p) ⁵² V, ⁵⁵ Mn(n, p) ⁵⁵ Cr and ⁵⁶ Fe(n, p) ⁵⁶ Mn reactions have been carried out up to 30 MeV incident neutron energy. Statistical model calculations, based on the Hauser–Feshbach formalism, have been carried out using the TALYS-1.0 and were compared with available experimental data in the literature and with ENDF/B-VII, T = 300 K; JENDL-3.3, T = 300 K and JEFF-3.1, T = 300 K evaluated libraries.     

Preparation,characterization, and lithographic applications of glycidyl methacrylate/methacrylic acid/t‐butyl‐4‐vinylphenyl carbonate terpolymers

At present, most negative working lithographic plates use organic solvents as a developing medium. These developers have the obvious disadvantages of toxicity, fire risk, and are more expensive than the aqueous developers. This work describes the synthesis and characterization of materials that have similar photoactive properties to existing materials, but are soluble in water or aqueous medium rather than organic solvents. These materials are terpolymers comprising of one sort of material to induce water solubility, such as methacrylic acid (MAA) and another material to give the photoactive response such as glycidyl methacrylate (GMA). The tertiary‐butyl‐4‐vinyl phenyl carbonate (t‐BOCVP) was added as a chemically amplifying agent. Various terpolymers were prepared via free‐radical solution polymerization, typically in methyl ethyl ketone (MEK). Crosslinking reaction was induced using mixed arylsulphonium hexafluoroantimonate (MAS+ ‐SbF) as a photogenerating acid. It was found that the films of the terpolymer containing 85 mol % of GMA unit with the addition of 5 mol % rather than 2 mol % of the t‐BOCVP in the feed ratio gave good acid resistance and good adhesion to the surface of the zinc plate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

New 2-Methyl-13-Icosenoic Acid from the Temperate Calcisponge <Emphasis Type="Italic">Leuconia johnstoni</Emphasis>

The fatty acid composition of the temperate calcareous marine sponge Leuconia johnstoni Carter 1871 (Calcaronea, Calcarea) was characterized for the first time in specimens collected off the Brittany coast of France over four years from October 2005 to September 2008. Forty-one fatty acids (FA) with chain lengths ranging from C₁₄ to C₂₂ were identified as fatty methyl esters (FAME) and N-acyl pyrrolidide (NAP) derivatives by gas chromatography–mass spectrometry (GC–MS). Twenty-two saturated fatty acids (SFA) were identified accounting for 52.1–59.0% of the total FA and dimethylacetals (DMA). In addition, among the SFA, we noticed the presence of numerous methyl-branched iso and anteiso FA, suggesting a large number of associated bacteria within L. johnstoni. Thirteen monounsaturated fatty acids (MUFA, 28.0–36.0% of total FA + DMA) were also identified as well as six polyunsaturated fatty acids (PUFA, 4.0–8.2%). A noticeable DMA was detected at a high level, particularly in September 2008 (11.8%), indicating the presence of plasmalogens in this sponge species. This calcareous sponge lacked the non-methylene-interrupted FA (NMI FA) with a Δ5,9 system typical of siliceous Demosponges and Hexactinellids. The occurrence of the unusual 8,13-octadecadienoic acid was reported for the first time as a minor PUFA in a calcareous sponge. The major FA, representing 20–25% of this sponge FA, was identified as the new 2-methyl-13-icosenoic acid from mass spectra of its methyl ester and its corresponding N-acyl pyrrolidide derivatives as well as a dimethyl disulfide adduct.     

Synthesis and characterizations of poly(ethylene-co-vinylalcohol)-grafted-poly(3-hydroxybutyrate-co-hydroxyvalerate) copolymers

Poly(ethylene-co-vinylalcohol)-grafted-poly(3-hydroxybutyrate-co-hydroxyvalerate) (EVOH-g-PHBV) was prepared by a catalyzed grafting of PHBV onto immiscible EVOH. These reactions were performed at high temperature in the molten state. The choices of Tin(II) bis(2-ethylhexanoate) (Sn(Oct)₂) and 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), as catalyst, were justified by a first study in an internal mixer. The catalyst quantity, reaction temperature and reaction time were optimized to apply them in the conditions of a reactive extrusion process with a co-rotating twin screw extruder. High reaction temperature, from 180 °C to 220 °C, associated to intensive mixing led to efficient grafting of PHBV onto EVOH, compatible with short residence times required.Rheological, thermal and morphological analyses were conducted to characterize the obtained copolymers. Molecular weights were determined by SEC. SEM imaging were made on cryo-fractured surfaces of blends extruded with and without catalyst. In most of reaction conditions, a compatible blend was obtained with a fine micro phase separation. Grafted copolymers were only obtained when well defined and controlled conditions are applied.     

Radical grafting of polar monomers onto polypropylene by reactive extrusion

Polypropylene (PP) was functionalized in the melt by grafting polar monomers using an internal mixer and a corotating twin‐screw extruder. 2,5‐Bis(tertbutylperoxy)‐2,5‐dimethylhexane (Luperox 101) and dicumyl peroxide (DP) were the used radical initiators. The polar monomers were itaconic acid (IAc), 2‐octen‐1‐ylsuccinic anhydride (OY), 2‐hydroxyethyl methacrylate (HEMA), and 3‐allyloxy‐1,2‐propanediol (AP). Grafting was quantified by FTIR combined to Elemental Analysis. Grafting degree depends mainly on monomer and initiator natures and concentrations. Grafting degree maxima were 3.9, 2, 9.5, and 3.9 wt %, respectively, for IAc, OY, HEMA, and AP. Some properties of the modified PP were evaluated. Thermal analysis indicated that the polarity of PP increased by grafting reaction and size‐exclusion chromatography showed that the grafting was not accompanied by a significant M_w and viscosity decrease. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of the host polymer on the nanomechanical and morphological properties of templated polymer films

Atomic force microscopy and nanoindentation have been applied to the study of thin molecularly templated polymer films. The template was chosen to be the readily hydrogen‐bonded cotinine molecule and three different polymer hosts, Elvamide® nylon, Nylon‐6, and poly(4‐vinylphenol) were compared. The host polymer was shown to affect the nature of the template‐host interaction resulting in varying surface morphologies and differences in the nanohardness. These observations were shown to reflect differences in the underlying interaction chemistry, specifically, whether or not the polymer may be imprinted in the film production process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 877‐883, 2013