Unsaturated polyesters

Summary The polymerization of maleic anhydride and 1,3-propylene glycol was carried out using p-toluenesulphonic acid as catalyst. The resulting material has been characterized by ir and H¹nmr spectroscopy, end group analysis and gel permeation chromatography. The percentage isomerization of maleate to fumarate has been correlated with the extension of polycondensation and the steric hindrance between the condensed functional groups.     

The drying of barley malt in the spouted bed dryer

The drying of barley malt was studied in a batch spouted-bed dryer using three inlet air temperatures (60, 80 and 90°C) and three initial masses of malt (25, 30 and 35 kg). One of the conclusions was that the drying can be conducted at higher temperatures than in the classical equipment. A general correlation was obtained through the use of reduced moisture and reduced time. A mathematical model which assumes only an external resistance of diffusion or heat transfer does not apply. Also, the model based on internal water diffusion does not predict the results. A new semi-empirical model based on semi-permeable membranes has been proposed. A method of using batch laboratory drying data to predict the performance of continuous spouted-bed driers has been outlined.     

Synthesis, enantiomeric resolution, and structure-activity relationship study of a series of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene MT2 receptor antagonists

Racemic N-(8-methoxy-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-10-ylmethyl)acetamide (compound 5) was previously identified as a novel selective MT(2) antagonist fulfilling the requirements of pharmacophore and 3D QSAR models. In this study the enantiomers of 5 were separated by medium-pressure liquid chromatography and behaved as the racemate. Compound 5 was modified at the acylaminomethyl side chain and at position C8. The resulting analogues generally behaved as melatonin receptor antagonists (GTPgammaS test) with a modest degree of selectivity (up to 10-fold) for the MT(2) receptor. Changes at the amide side chain led to a decrease in binding affinity, whereas 8-acetyl and 8-methyl derivatives 12 and 11, respectively, were as potent as the 8-methoxy parent compound 5. Docking experiments with an MT(2) receptor model suggested binding modes consistent with the observed SARs and with the lack of selectivity of the enantiomers of 5.     

Phase evolution in plasma sprayed Nb2O5 coatings

Nb₂O₅ polymorphism and defect chemistry depend on the temperature, pressure, atmosphere composition and the initial crystallography. Plasma spray of Nb₂O₅ is a pathway to form coatings with in-situ metastable and nonstoichiometric phases, however so far unexplored. This study aimed to understand the phase evolution of plasma sprayed Nb₂O₅ coatings, and its effect on their morphology and properties. Phase evolution from H-Nb₂O₅ in the feedstock, to T-Nb₂O₅, TT-Nb₂O₅, N-Nb₂O₅, H-Nb₂O₅, Nb₁₂O₂₉ and NbO₂ in the coatings depends on the plasma Ar/H₂ ratio and its related enthalpy. The microstructure shows a layered distribution of nonstoichiometric phases at the splat boundaries and splat cores composed of T-Nb₂O₅ or TT-Nb₂O₅. The presence and distribution of these phases are related to the thermomechanical and electrical properties. The mechanisms driving the formation of these coatings are based on the Nb₂O₅ incongruent vaporization which promote retention of nonstoichiometric phases and the rapid solidification of metastable phases.     

Development of cereal bar with pineapple skin

The cereal bars are multi-component products consisting of cereals, dried fruit and syrup binder and may be added to the consumable parts of fruits and vegetables which usually are not exploited and have high nutritional value, thereby reducing food waste. It was developed a jam with pineapple skin, which it was utilized in 13.5% in the cereal bar formulation. The cereal bar was sensorial evaluated and had its centesimal and mineral composition determined. The new product achieved average of 8.3 for global impression using 9 points hedonic scale, 91% of acceptance rate and 67% of purchase intent. In this first use of pineapple skin jam as food ingredient it can be concluded that its aggregation in the cereal bar formula is feasible, making an accepted product with fibers, proteins and minerals, as an alternative to traditional cereal bars.     

Polysulfone/Metal Nanocomposites by Simultaneous Photoinduced Crosslinking and Redox Reaction

A diacrylate polysulfone oligomer is synthesized and used as the acrylic oligomer for the in situ synthesis of noble metal/PSU nanocomposites through UV‐induced simultaneous radical polymerization of acrylic functionalities and NP formation by reduction of their precursors. Thus, silver or gold NPs are formed in situ during polymer network formation. FESEM analysis of the morphology of the cured systems demonstrates that the nanoparticles of the noble metals are homogeneously distributed in the network without macroscopic agglomeration.

     

Sisal fibers treated with NaOH and benzophenonetetracarboxylic dianhydride as reinforcement of phenolic matrix

In this work, composites based on a phenolic matrix and untreated‐ and treated sisal fibers were prepared. The treated sisal fibers used were those reacted with NaOH 2% solution and esterified using benzophenonetetracarboxylic dianhydride (BTDA). These treated fibers were modified with the objective of improving the adhesion of the fiber–matrix interface, which in turn influences the properties of the composites. BTDA was chosen as the esterifying agent to take advantage of the possibility of introducing the polar and aromatic groups that are also present in the matrix structure into the surface of the fiber, which could then intensify the interactions occurring in the fiber–matrix interface. The fibers were then analyzed by SEM and FTIR to ascertain their chemical composition. The results showed that the fibers had been successfully modified. The composites (reinforced with 15%, w/w of 3.0 cm length sisal fiber randomly distributed) were characterized by SEM, impact strength, and water absorption capacity. In the tests conducted, the response of the composites was affected both by properties of the matrix and the fibers, besides the interfacial properties of the fiber–matrix. Overall, the results showed that the fiber treatment resulted in a composite that was less hygroscopic although with somewhat lower impact strength, when compared with the composite reinforced with untreated sisal fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparison of the catalytic performance of YIG garnets and Fe-containing oxides catalysts for oxidation of ethylbenzene

Iron-containing garnets (YIG) were used as catalysts for selective oxidation of ethylbenzene (EB) in the presence of H₂O₂ as oxidant. The catalysts comprising of two series of garnets e.g., Y₃(Fe_1–xZn_x)₅O₁₂ and Y₃(Fe_1–xNi_x)₅O₁₂ had distinct Zn and Ni contents (x = 0.00 0.01, 0.03, and 0.05). XRD, Raman and FTIR spectroscopies revealed that the cubic structure of Y₃Fe₅O₁₂ garnet was present for x = 0.00 and 0.01. For higher contents, the garnets had the Y₃Fe₅O₁₂ phase besides hematite (α-Fe₂O₃). The catalytic activity was dependent on the contents of metals in the garnets with Y₃Fe_4·97Ni_0·03O_12-γ and Y₃Fe_4·95Zn_0·05O_12-γ catalysts achieving better results. The influence of the reaction conditions such as reaction time, reaction temperature and effect of the solvents as well as the substrates to H₂O₂ molar ratios were studied. SEM-EDS, XPS and EPR results demonstrated the affinity of the Fe²⁺/Fe³⁺ pairs with Ni²⁺ species for the ethylbenzene molecule, which gave an EB conversion of 77% with a good production of acetophenone over the Y₃Fe_4·97Ni_0·03O_12-γ catalyst compared to other binary and ternary solids.     

On the invariant reactions in the Mo-rich portion of the Mo-Si system

The Mo-Si system presents two invariant reactions (eutectic and peritectic) in the Mo-rich region; these reactions involve the Liquid, Mo_ss, Mo₃Si, and Mo₅Si₃ phases. The results presented in the literature show disagreement about the specific reactions, with two proposals being reported: (1) L + Mo_ss ⇔ Mo₃Si and L ⇔ Mo₃Si + Mo₅Si₃; and (2) L + Mo₅Si₃ ⇔ Mo₃Si and L ⇔ Mo_ss + Mo₃Si. In order to contribute to this subject, we have produced several Mo-Si alloys (21 to 29 at.% Si) via arc melting and evaluated the as-cast microstructures through x-ray diffraction (XRD), scanning electron microscope/backscattered electron image (SEM/BSEI), and energy dispersive x-ray analysis (EDS). The primary phases identified in the different samples were Mo_ss, Mo₃Si, and Mo₅Si₃. The results have indicated clearly the existence of a eutectic reaction involving the phases Mo₃Si and Mo₅Si₃, confirming the existence of the L + Mo_ss ⇔ Mo₃Si and L ⇔ Mo₃Si + Mo₅Si₃ invariant reactions. In addition, alloys with composition 26 at.% Si and 27 at.% Si presented Mo₃Si and Mo₅Si₃ as primary phases, respectively, indicating that the liquid eutectic composition is located between those values.