Anionic copolymerization of DGEBA with two bicyclic bis(γ-lactone) derivatives using tertiary amines as initiators

The anionic copolymerization, to form thermosets, of diglycidylether of bisphenol A (DGEBA) with two condensed bis(γ-lactone)s (bisMe and bisPhe) using 4-(N,N-dimethylamino)pyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1-methylimidazole (1MI) as initiators was studied by differential scanning calorimetry (DSC). The kinetics was evaluated by isoconversional procedures. The evolution of the typical functional groups that form or disappear during curing was followed by Fourier transform infrared in the attenuated-total-reflection mode (FTIR/ATR) to clarify the reactive processes that takes place. Unexpected processes, which lead to the formation of five-membered lactones, were detected when non-stoichiometric proportions of monomers were used. The stoichiometric DGEBA/bislactone ratio produces the expected alternate poly(ester-ketone) network. The thermal degradability of the materials obtained was evaluated by TGA, and their reworkable character was confirmed. Materials obtained from stoichiometric mixtures were completely soluble in ethanolic KOH.     

Process and recyclability analyses of innovative bio‐composite for tray

The originality of the present study is to give complete and pragmatic information associated with the preparation of a totally bio‐based composite. It covers the most relevant investigations from analyses of the fibres used as reinforcing elements to the final product acquisition and its recyclability analyses. This study is destined for packaging areas. It demonstrates the three‐dimensional formation processes with these new kinds of bio‐composites, as well as the recyclable features related to the prepared materials. Thus, several processing parameters were studied and a final tray was prepared. The addition of the fibres gives rise to an increase of the tray stiffness, when a flexible biopolymer is used as a matrix. The prepared bio‐composites were recycled several times (10 recycling cycles) and found that they maintain their most relevant characteristics. Thus, such bio‐composites can be reused several times. All these data, including a prototype sample prepared as a demonstrator, support the innovative and sustainable character of the packaging materials described. Copyright © 2010 John Wiley & Sons, Ltd.     

New improved thermosets obtained from DGEBA and a hyperbranched poly(ester-amide)

The influence on the curing process of a commercial hydroxy-functionalized hyperbranched poly(ester-amide) (HBP) Hybrane^® S1200 on diglycidylether of bisphenol A (DGEBA) was studied. By Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) the curing reaction was studied and the covalent incorporation of the modifier in the matrix was proved. By Thermomechanical Analysis (TMA) the reduction of the contraction after gelation on changing the S1200 proportion was observed. The incorporation of S1200 increased the glass transition temperature (T_g) and reduced the overall shrinkage, specially after gelation. The modified materials were more thermally degradable than neat DGEBA thermosets. Thermal expansion coefficient, Young's modulus, impact strength and microhardness were improved without compromising the thermomechanical characteristics. The water uptake behaviour was also evaluated.     

Kinetic study by FTIR,TMA, and DSC of the curing of a mixture of DGEBA resin and γ‐butyrolactone catalyzed by ytterbium triflate

A mixture of diglycidylether of bisphenol A (DGEBA) and γ‐butyrolactone (γ‐BL) was cured in the presence of ytterbium triflate as a catalyst. The kinetics of the various elemental processes that occur in the curing process were studied by means of isothermal curing in the FTIR spectrometer. The kinetics of the contraction during the curing was also evaluated by TMA. In both cases, the kinetics was analyzed by means of isoconversional procedure and the kinetic model was determined with the so‐called compensation effect (isokinetic relationship). The isothermal kinetic analysis was compared with that obtained by dynamic curing in DSC. We found that all the reactive processes and the contraction follow a surface‐controlled reaction type of kinetic mechanism, R₃. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 381–393, 2004     

The use of agroindustrial by-products for biosurfactant production

Traditionally, hydrocarbons have been used for biosurfactant production. However, urban waste, peat pressate and agroindustrial by-products, such as olive oil mill effluent and acid whey, are possible substitutes for microbial growth and biosurfactant production. The state of the art has been reviewed, augmented by some new information onPseudomonas fermentation of olive oil mill effluent. More research is needed to improve yields and production economics.     

Prediction of fatty acid composition using a NIRS fibre optics probe at two different locations of ham subcutaneous fat

NIR technology was used to analyze the fatty acid composition of fat tissue from conjugated linoleic acid fed pigs by direct application of a fibre optics probe on two different locations of subcutaneous fat. One hundred and fifty-three pigs were fed three different diets and the fatty acid profile of subcutaneous fat from Gluteus medius was analyzed using gas chromatography and FT-NIR in a longitudinal and transversal cut. Spectra were acquired using a Bruker Optics Matrix-F duplex spectrometer equipped with a fibre optics probe (IN-268-2). Total saturated, monounsaturated and polyunsaturated together as well as oleic and stearic fatty acids were predicted accurately (R² > 0.70), myristic, and linoleic fatty acids were predicted with lower accuracy (0.60 < R² < 0.70), while palmitic, asclepic and α-linolenic fatty acids were poorly predicted (R² < 0.60). Results indicated that NIR technology has potential as a rapid tool to discriminate carcasses from animals fed diets with different fatty acid composition by a direct measurement on the fat from the ham.     

Copolymerization of diglycidylether of bisphenol A and bicyclic bis(γ‐lactone)s using rare earth metal triflates as initiators studied with infrared spectroscopy

The thermal cationic curing of mixtures, in various proportions, of diglycidylether of bisphenol A with two substituted condensed bis(γ‐lactone)s initiated using scandium, ytterbium and lanthanum triflates or a conventional boron trifluoride monoethylamine (BF₃·MEA) initiator was investigated. The evolution of the various reactive groups was followed by means of attenuated total reflection Fourier transform infrared spectroscopy. The formation of mono‐spiroorthoesters (monoSOE)s and bis‐spiroorthoesters (bisSOE)s is discussed. The polymerization of bisSOE structures led to the formation of ether–ester–ketone repeat units, which implied the cationic polymerization took place by a tandem reaction. The use of scandium triflate as an initiator led to the highest chemical incorporation of lactone in the network. Moreover, this initiator was the most active, incorporating a higher proportion of lactone in a shorter time. In contrast, the conventional BF₃·MEA initiator incorporated the lowest proportion of bislactone in the cured material. Copyright © 2010 Society of Chemical Industry     

New surfactant isolated fromPseudomonas 42A2

Pseudomonas 42A2 is a gram negative rod isolated from a water sample. The new strain, when cultivated in mineral salt medium with olive oil as carbon source, produced a new surface active compound which was isolated and identified as dihydroxyoctadecenoic acid. No rhamnolipids were detected in the organic extract. The surface tension of the new compound is 30 mN/m at 50°C.     

Chemical characterization and physicochemical behavior of biosurfactants

Microbes have been isolated from soil and water samples after an enrichment culture process with kerosene and tested for biosurfactant production by measuring the surface and interfacial tensions and emulsification power of culture broths. The isolation and characterization of extracellular surface-active agents from the culture broth of Pseudomonas aeruginosa 44T1 strain have been made. Preliminary structure identification with specific TLC reagents of the CHCl₃MeOH (2:1) extracts showed two spots with a glycolipidic structure and Rf values of 0.70 and 0.45, respectively, using the solvent system CHCl₃:MeOH:H₂O (65:25:4). Separation of surface active agents by Chromatographic absorption column in Florisil or silica gel and further spectroscopic study (IR, 1H-NMR, 13C-NMR) and chemical degradation techniques (acid and alkaline hydrolysis) gave a structure of β[β(2-0-α-L-rhamnopyranosyloxy)decanoyl] decanoic acid and β[β (2-0-α-L-rhamnopyranosyl-α-L-rhamnopyranosyloxy) decanoyloxy] decanoic acid (glycolipid A and glycolipid B, respectively) for the two glycolipids detected. A new method of mass spectrometry, fast atom bombardment mass spectrometry (FABMS), was used to probe molecular structure. The mass spectra obtained contain molecular weight recognition and sequence information signals, and they are in agreement with the proposed structures. Physicochemical evaluations of the two isolated glycolipids were made. The minimum surface tension obtained was 25 mN/m in water solutions. At pH 7 the CMC value was 11 ppm. In both cases, at pH 3 the CMC was displaced to lower and at pH 9 it was displaced to higher concentration values. Glycolipid B showed a lower value of interfacial tension (0.2 mN/m) than glycolipid A (1.0 mN/m). Glycolipid A showed a lower CMC value at alkaline pH, whereas glycolipid B had a lower CMC at acidic pH than at alkaline pH.     

Preparation of prepolymers from diglycidylether of bisphenol A containing imide groups

Epoxy resins derived from Bisphenol A have been modified with new diphenols containing imide moieties in order to improve their thermal properties. The diphenols have been synthesized from dianhydrides and aminophenols by condensation reactions. Diphenols as well as modified resins have been characterized by IR and NMR spectroscopy. The thermal characteristics were evaluated by DSC and TGA.