Potential of Cu–saponite catalysts for soot combustion

H– and Na–saponite supports have been prepared by several synthesis approaches. 5% Cu/saponite catalysts have been prepared and tested for soot combustion in a NOx + O2 + N2 gas flow and with soot and catalyst mixed in loose contact mode. XRD, FT-IR, N2 adsorption and TEM characterization results revealed that the use of either surfactant or microwaves during the synthesis led to delamination of the saponite support, yielding high surface area and small crystallite size materials. The degree of delamination affected further copper oxide dispersion and soot combustion capacity of the Cu/saponite catalysts. All Cu/saponite catalysts were active for soot combustion, and the NO2-assisted mechanism seemed to prevail. The best activity was achieved with copper oxide supported on a Na–saponite prepared at pH 13 and with surfactant. This best activity was attributed to the efficient copper oxide dispersion on the high surface area delaminated saponite (603 m2 g−1) and to the presence of Na. Copper oxide reduction in H2-TPR experiments occurred at lower temperature for the Na-containing catalysts than for the H-containing counterparts, and all Cu/Na–saponite catalysts were more active for soot combustion than the corresponding Cu/H–saponite catalysts.

Water-triggered spontaneous surface patterning in thin films of mexylaminotriazine molecular glasses

Surface patterning that occurs spontaneously during the formation of a thin film is a powerful tool for controlling film morphology at the nanoscale level because it avoids the need for further processing. However, one must first learn under which conditions these patterning phenomena occur or not, and how to achieve control over the surface morphologies that are generated. Mexylaminotriazine-based molecular glasses are small molecules that can readily form amorphous thin films. It was discovered that this class of materials can either form smooth films, or films exhibiting either dome or pore patterns. Depending on the conditions, these patterns can be selectively obtained during film deposition by spin-coating. It was determined that this behavior is controlled by the presence of water or, more generally, of a solvent in which the compounds are insoluble, and that the relative amount and volatility of this poor solvent determines which type of surface relief is obtained. Moreover, AFM and FT-IR spectroscopy have revealed that the thin films are amorphous independently of surface morphology, and no difference was observed at the molecular or supramolecular level. These findings make this class of materials and this patterning approach in general extremely appealing for the control of surface morphology with organic nanostructures.

Distribution of melamine in polyester-melamine surface coatings cured under nonisothermal conditions

The influence of experimental cure parameters on the diffusion of reactive species in polyester-melamine thermoset coatings during curing has been investigated with X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared. The diffusion of melamine plays a vital role in the curing process and, therefore, in the ultimate properties of coatings. At a low (

Thermosetting Blends of Polybenzoxazine and Poly(ε-caprolactone): Phase Behavior and Intermolecular Specific Interactions

Polybenzoxazine (PBA-a)/poly(epsilon-caprolactone) (PCL) blends were prepared by an in situ curing reaction of benzoxazine (BA-a) in the presence of PCL. Before curing, the benzoxazine (BA-a)/PCL blends are miscible, which was evidenced by the behaviors of single and composition-dependant glass transition temperature and equilibrium melting point depression. However, the phase separation induced by polymerization was observed after curing at elevated temperature. It was expected that after curing, the PBA-a/PCL blends would be miscible since the phenolic hydroxyls in the PBA-a molecular backbone have the potential to form inter- molecular hydrogen-bonding interactions with the carbonyls of PCL and thus would fulfil the miscibility of the blends. The resulting morphology of the blends prompted an investigation of the status of association between PBA-a and PCL under the curing conditions. Although Fourier-transform infrared spectroscopy (FT-IR) showed that there were intermolecular hydrogen-bonding interactions between PBA-a and PCL at room temperature, especially for the PCL-rich blends, the results of variable temperature FT-IR spectroscopy by the model compound indicate that the phenolic hydroxyl groups could not form efficient intermolecular hydrogen-bonding interactions at elevated temperatures, i.e., the phenolic hydroxyl groups existed mainly in the non-associated form in the system during curing. The results are valuable to understand the effect of curing temperature on the resulting morphology of the thermosetting blends. SEM micrograph of the dichloromethane-etched fracture surface of a 90:10 PBA-a PCL blend showing a heterogeneous morphology.

Dimeric allylpalladium(II) complexes with pyrazolate bridges: Synthesis, characterization, structure and thermal behaviour

The synthesis, characterization and thermal behaviour of some new dimeric allylpalladium (II) complexes bridged by pyrazolate ligands are reported. The complexes [Pd(mu-3, 5-R'(2)pz)(eta(3)-CH2C(R)CH2)](2) [R = H; R'= CH(CH3)(2) (1a); R = H, R' = C(CH3)(3) (1b), R = H; R' = CF3 (1c); R = CH3, R' = CH(CH3)(2) (2a); R = CH3, R' = C(CH3)(3) (2b); and R = CH3, R' = CF3 (2c)] have been prepared by the room temperature reaction of [Pd(eta(3)-CH2C(R)CH2)(acac)](acac = acetylacetonate) with 3,5-disubstituted pyrazoles in acetonitrile solution. The complexes have been characterized by NMR (H-1, C-13{H-1}), FT-IR, and elemental analyses. The structure of a representative complex, viz. 2c, has been established by single-crystal X-ray diffraction. The dinuclear molecule features two formally square planar palladium centres which are bridged by two pyrazole ligands and the coordination of each metal centre is completed by allyl substituents. The molecule has non-crystallographic mirror symmetry. Thermogravimetric studies have been carried out to evaluate the thermal stability of these complexes. Most of the complexes thermally decompose in argon atmosphere to give nanocrystals of palladium, which have been characterized by XRD, SEM and TEM. However, complex 2c can be sublimed in vacuo at 2 mbar without decomposition. The equilibrium vapour pressure of 2c has been measured by the Knudsen effusion technique. The vapour pressure of the complex 2c could be expressed by the relation: In (p/Pa)(+/- 0.06) = -18047.3/T + 46.85. The enthalpy and entropy of vapourization are found to be 150.0 +/- 3 kJ mol(-1) and 389.5 +/- 8 J K-1 mol(-1), respectively. (c) 2005 Elsevier B.V. All rights reserved.

Screening, characterization and flocculating property of carbohydrate polymer from newly isolated Enterobacter cloacae WD7

A total of 188 carbohydrate polymer-producing bacterial strains were isolated from recycled sludge of five seafood processing plants. Among three selected isolates, identified as Enterobacter cloacae WD7, Enterobacter agglomerans WD50 and Pseudomonas alcaligenes WD22. E. cloacae WD7 generated a viscous culture broth exhibiting the highest flocculating activity and a crude polymer yield of 2.27 g/L after 3 days cultivation. Partial purification of this polymer was performed by precipitation with 95% ethanol, dialysis and freeze-drying. It was characterized as an acidic heteropolysaccharide, composed of neutral sugars (29.4%), uronic acids (14.2%) and amino sugars (0.93%). The functional group analysis by FT-IR spectroscopy showed the presence of hydroxyl, carboxyl, carbonyl and methoxyl groups. Thermal analysis by DSC showed the crystalline transition and the crystalline melting point (T-m) at 300 degrees C. This polysaccharide was soluble in water and insoluble in any organic solvents tested; gelation occurred under alkaline conditions in the presence of divalent cations in which copper as CuSO4 gave the best result. Studies on the flocculation property revealed that this polysaccharide was stable at 4-60 degrees C and pH 5-7. The optimal concentrations for the flocculating activity were 2 mg/L polysaccharide and 40 mM CaCl2 which played the synergistic effect on kaolin flocculation. Moreover, this polysaccharide could flocculate the kaolin suspension over a wide range of pH (pH 2-8) and temperature (4-50 degrees C) tested in the presence of CaCl2. (c) 2006 Elsevier Ltd. All rights reserved.

Caratterizzazione delle Prestazioni di Protezione al Fuoco di Vernici Intumescenti

Le pitture intumescenti sono utilizzate come protettivi passivi antincendio nel settore delle costruzioni. In particolare sono utilizzate per aumentare la resistenza al fuoco di elementi in acciaio. Le proprietà termiche di questi rivestimenti sono spesso sconosciute o difficili da stimare per via del fatto che variano notevolmente durante il processo di espansione che subisce l’intumescente quando esposto al calore di un incendio. Per questa ragione la validazione della resistenza al fuoco di un rivestimento presente in commercio si basa su metodi costosi economicamente e come tempi di esecuzione nel quale ciascuna trave e colonna rivestita di protettivo deve essere testata una alla volta attraverso il test di resistenza al fuoco della curva cellulosica. In questo lavoro di tesi adottando invece un approccio basato sulla modellazione termica del rivestimento intumescente si ottiene un aiuto nella semplificazione della procedura di test ed un supporto nella progettazione della resistenza al fuoco delle strutture. Il tratto di unione nei vari passaggi della presente tesi è stata la metodologia di stima del comportamento termico sconosciuto, tale metodologia di stima è la “Inverse Parameter Estimation”. Nella prima fase vi è stata la caratterizzazione chimico fisica della vernice per mezzo di differenti apparecchiature come la DSC, la TGA e l’FT-IR che ci hanno permesso di ottenere la composizione qualitativa e le temperature a cui avvengono i principali processi chimici e fisici che subisce la pittura come anche le entalpie legate a questi eventi. Nella seconda fase si è proceduto alla caratterizzazione termica delle pitture al fine di ottenerne il valore di conduttività termica equivalente. A tale scopo si sono prima utilizzate le temperature dell’acciaio di prove termiche alla fornace con riscaldamento secondo lo standard ISO-834 e successivamente per meglio definire le condizioni al contorno si è presa come fonte di calore un cono calorimetrico in cui la misura della temperatura avveniva direttamente nello spessore del’intumescente. I valori di conduttività ottenuti sono risultati congruenti con la letteratura scientifica e hanno mostrato la dipendenza della stessa dalla temperatura, mentre si è mostrata poco variante rispetto allo spessore di vernice deposto ed alla geometria di campione utilizzato.

Effect of sample preparation on the thermal degradation of metal-added biomass

The present study investigates the effect of different sample preparation methods on the pyrolysis behaviour of metal-added biomass; Willow samples were compared in the presence of two salts of zinc and lead containing sulphate and nitrate anions which were added to the wood samples with three different techniques as dry-mixing, impregnation and ion-exchange. The effect of acid and water wash as common demineralisation pre-treatments were also analysed to evaluate their roles in the thermal degradation of the biomass. Results from thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-mass spectrometry (Py-MS) measurements indicated that these pre-treatments change the matrix and the physical-chemical properties of wood. Results suggested that these structural changes increase the thermal stability of cellulose during pyrolysis. Sample preparation was also found to be a crucial factor during pyrolysis; different anions of metal salts changed the weight loss rate curves of wood material, which indicates changes in the primary degradation process of the biomass. Results also showed that dry-mixing, impregnation or ion-exchange influence the thermal behaviour of wood in different ways when a chosen metal salt was and added to the wood material. © 2011 Elsevier B.V. All rights reserved.

Environmental degradation of polyethylene-based plastics

The criteria involved in the degradation of polyethylene-based degradable polymer samples have been investigated, with a view to obtaining a clearer mechanism of photo-biodegradation. The compatibility of degradable polymer samples during materials recycling was also studied. Commercial and laboratory prepared degradable polymer samples were oxidised in different environments and the oxidation products formed were studied using various analytical chromatographic and spectroscopic techniques such as HPLC, FT-IR and NMR. It was found that commercial degradable polymer samples which are based on the ECO systems, degrade predominantly via the Norrish II process, whereas the other degradable systems studied (starch-filled polyethylene systems, transition metal systems, including metal carboxylate based polyethylene systems and the photoantioxidant-activator systems) photodegrade essentially via the Norrish I process. In all cases, the major photoxidation products extracted from the degradable polymer samples were found to be carboxylic acids, although, in the polymer itself a mixture of carbonyl containing products such as esters, lactones, ketones and aldehydes was observed. The study also found that the formation of these hydrophilic carbonyl products causes surface swelling of the polymer, thus making bioerosion possible. It was thus concluded that environmental degradation of LDPE is a two step process, the initiation stage being oxidation of the polymer which gives rise to bioassimilable products, which are consequently bioeroded in the second stage, (the biodegradation step). Recycling of the degradable polymer samples as 10% homogeneous and heterogeneous blends was carried out using a single screw extruder (180°C and 210°C) and an internal mixer (190°C). The study showed that commercial degradable polymer samples may be recycled with a minimal loss in their properties.

The chemical modification of polymer blends by reactive processing

The primary objective of this research was to examine the concepts of the chemical modification of polymer blends by reactive processing using interlinking agents (multi-functional, activated vinyl compounds; trimethylolpropane triacrylates {TRIS} and divinylbenzene {DVD}) to target in-situ interpolymer formation between immiscible polymers in PS/EPDM blends via peroxide-initiated free radical reactions during melt mixing. From a comprehensive survey of previous studies of compatibility enhancement in polystyrene blends, it was recognised that reactive processing offers opportunities for technological success that have not yet been fully realised; learning from this study is expected to assist in the development and application of this potential. In an experimental-scale operation for the simultaneous melt blending and reactive processing of both polymers, involving manual injection of precise reactive agent/free radical initiator mixtures directly into molten polymer within an internal mixer, torque changes were distinct, quantifiable and rationalised by ongoing physical and chemical effects. EPDM content of PS/EPDM blends was the prime determinant of torque increases on addition of TRIS, itself liable to self-polymerisation at high additions, with little indication of PS reaction in initial reactively processed blends with TRIS, though blend compatibility, from visual assessment of morphology by SEM, was nevertheless improved. Suitable operating windows were defined for the optimisation of reactive blending, for use once routes to encourage PS reaction could be identified. The effectiveness of PS modification by reactive processing with interlinking agents was increased by the selection of process conditions to target specific reaction routes, assessed by spectroscopy (FT-IR and NMR) and thermal analysis (DSC) coupled dichloromethane extraction and fractionation of PS. Initiator concentration was crucial in balancing desired PS modification and interlinking agent self-polymerisation, most particularly with TRIS. Pre-addition of initiator to PS was beneficial in the enhancement of TRIS binding to PS and minimisation of modifier polymerisation; believed to arise from direct formation of polystyryl radicals for addition to active unsaturation in TRIS. DVB was found to be a "compatible" modifier for PS, but its efficacy was not quantified. Application of routes for PS reaction in PS/EPDM blends was successful for in-situ formation of interpolymer (shown by sequential solvent extraction combined with FT-IR and DSC analysis); the predominant outcome depending on the degree of reaction of each component, with optimum "between-phase" interpolymer formed under conditions selected for equalisation of differing component reactivities and avoidance of competitive processes. This was achieved for combined addition of TRIS+DVB at optimum initiator concentrations with initiator pre-addition to PS. Improvements in blend compatibility (by tensiles, SEM and thermal analysis) were shown in all cases with significant interpolymer formation, though physical benefits were not; morphology and other reactive effects were also important factors. Interpolymer from specific "between-phase" reaction of blend components and interlinking agent was vital for the realisation of positive performance on compatibilisation by the chemical modification of polymer blends by reactive processing.

The study and characterisation of water-based latices used for can coating interiors

Water-based latices, used in the production of internal liners for beer/beverage cans, were investigated using a number of analytical techniques. The epoxy-graft-acrylic polymers, used to prepare the latices, and films, produced from those latices, were also examined. It was confirmed that acrylic polymer preferentially grafts onto higher molecular weight portions of the epoxy polymer. The amount of epoxy remaining ungrafted was determined to be 80%. This figure is higher than was previously thought. Molecular weight distribution studies were carried out on the epoxy and epoxy-g-acrylic resins. A quantitative method for determining copolymer composition using GPC was evaluated. The GPC method was also used to determine polymer composition as a function of molecular weight. IR spectroscopy was used to determine the total level of acrylic modification of the polymers and NMR was used to determine the level of grafting. Particle size determinations were carried out using transmission electron microscopy and dynamic light scattering. Levels of stabilising amine greatly affected the viscosity of the latex, particle size and amount of soluble polymer but the core particle size, as determined using TEM, was unaffected. NMR spectra of the latices produced spectra only from solvents and amine modifiers. Using solid-state CP/MAS/freezing techniques spectra from the epoxy component could be observed. FT-IR spectra of the latices were obtained after special subtraction of water. The only difference between the spectra of the latices and those of the dry film were due to the presence of the solvents in the former. A distinctive morphology in the films produced from the latices was observed. This suggested that the micelle structure of the latex survives the film forming process. If insufficient acrylic is present, large epoxy domains are produced which gives rise to poor film characteristics. Casting the polymers from organic solutions failed to produce similar morphology.

Oxidation studies of a novel barrier polymer system

The thermal oxidation of two model compounds representing the aromatic polyamide, MXD6 (poly m-xylylene adipamide) have been investigated. The model compounds (having different chemical structures, viz, one corresponding to the aromatic part of the chain and the other to the aliphatic part), based on the structure of MXD6 were prepared and reactions with different concentrations of cobalt ions examined with the aim of identifying the role of the different structural components of MXD6 on the mechanism of oxidation. The study showed that cobalt, in the presence of sodium phosphite (which acts as an antioxidant for MXD6 and the model compounds), increases the oxidation of the model compounds. It is believed that the cobalt acts predominantly as a catalyst for the decomposition of hydroperoxides, formed during oxidation of the models in the melt phase, to free radical products and to a lesser extent as a catalyst for the initiation of the oxidation reaction by complex formation with the amide, which is more likely to take place in the solid phase. An oxidation cycle has been proposed consisting of two parts both of which will occur, to some extent under all conditions of oxidation (in the melt and in the solid phase), but their individual predominance must be determined by the prevailing oxygen pressure at the reaction site. The different aspects of this proposed mechanism were examined from extensive model compound studies, and the evidence based on the nature of product formation and the kinetics of these reactions. Main techniques used to compare the rates of oxidation and the study of kinetics included, oxygen absorption, FT-IR, UV and TGA. HPLC was used for product separation and identification.

Use of amino acids as counterions improves the solubility of the BCS II model drug, indomethacin

The number of new chemical entities (NCE) is increasing every day after the introduction of combinatorial chemistry and high throughput screening to the drug discovery cycle. One third of these new compounds have aqueous solubility less than 20µg/mL [1]. Therefore, a great deal of interest has been forwarded to the salt formation technique to overcome solubility limitations. This study aims to improve the drug solubility of a Biopharmaceutical Classification System class II (BCS II) model drug (Indomethacin; IND) using basic amino acids (L-arginine, L-lysine and L-histidine) as counterions. Three new salts were prepared using freeze drying method and characterised by FT-IR spectroscopy, proton nuclear magnetic resonance ((1)HNMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). The effect of pH on IND solubility was also investigated using pH-solubility profile. Both arginine and lysine formed novel salts with IND, while histidine failed to dissociate the free acid and in turn no salt was formed. Arginine and lysine increased IND solubility by 10,000 and 2296 fold, respectively. An increase in dissolution rate was also observed for the novel salts. Since these new salts have improved IND solubility to that similar to BCS class I drugs, IND salts could be considered for possible waivers of bioequivalence.

Preparation and characterisation of amino acids based trimethoprim salts

Trimethoprim (TMP) is a dihydrofolate reductase (DHFR) inhibitor which prevents the conversion of dihydrofolic acid into tetrahydrofolic acid, resulting in the depletion of the latter and leading to bacterial death. Oral bioavailability of TMP is hindered by both its low solubility and low permeability. This study aims to prepare novel salts of TMP using anionic amino acids; aspartic and glutamic acid as counter ions in order to improve solubility and dissolution. TMP salts were prepared by lyophilisation and characterized using FT-IR spectroscopy, proton nuclear magnetic resonance (1HNMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). Both the amino acids formed salts with TMP in a 1:1 molar ratio and showed a 280 fold improvement in solubility. Investigation of the microbiological activity of the prepared salts against TMP sensitive Escherichia coli showed that the new salts not only retained antibacterial activity but also exhibited higher zone of inhibition which was attributed to improved physicochemical characters such as higher solubility and dissolution. The results are an important finding that could potentially impact on faster onset of antibacterial activity and reduced therapeutic dose when administered to patients. Studies are underway investigating the effect of ion-pairing TMP with amino acids on the permeability profile of the drug.

Dry powder inhalation of macromolecules using novel PEG-co-polyester microparticle carriers

This study investigated optimizing the formulation parameters for encapsulation of a model mucinolytic enzyme, a-chymotrypsin (a-CH), within a novel polymer; poly(ethylene glycol)-co-poly(glycerol adipate-co-?-pentadecalactone), PEG-co-(PGA-co-PDL) which were then applied to the formulation of DNase I. a-CH or DNase I loaded microparticles were prepared via spray drying from double emulsion (w(1)/o/w(2)) utilizing chloroform (CHF) as the organic solvent, l-leucine as a dispersibility enhancer and an internal aqueous phase (w(1)) containing PEG4500 or Pluronic(®) F-68 (PLF68). a-CH released from microparticles was investigated for bioactivity using the azocasein assay and the mucinolytic activity was assessed utilizing the degradation of mucin suspension assay. The chemical structure of PEG-co-(PGA-co-PDL) was characterized by (1)H NMR and FT-IR with both analyses confirming PEG incorporated into the polymer backbone, and any unreacted units removed. Optimum formulation a-CH-CHF/PLF68, 1% produced the highest bioactivity, enzyme encapsulation (20.08±3.91%), loading (22.31±4.34µg/mg), FPF (fine particle fraction) (37.63±0.97%); FPD (fine particle dose) (179.88±9.43µg), MMAD (mass median aerodynamic diameter) (2.95±1.61µm), and the mucinolytic activity was equal to the native non-encapsulated enzyme up to 5h. DNase I-CHF/PLF68, 1% resulted in enzyme encapsulation (17.44±3.11%), loading (19.31±3.27µg/mg) and activity (81.9±2.7%). The results indicate PEG-co-(PGA-co-PDL) can be considered as a potential biodegradable polymer carrier for dry powder inhalation of macromolecules for treatment of local pulmonary diseases.