An Investigation of the Reaction of Epoxides with Wood

Abstract

The reaction of wood with two functionalised epoxides, allyl glycidyl ether (AGE) and glycidyl methacrylate (GMA), has been studied. For the reaction with whole wood samples of Scots Pine (Pinus sylvestris), maximum weight percent gains (WPG's) of 20% (GMA) and 7% (AGE) were obtained using pyridine as a solvent/catalyst. However, reaction of the epoxides with thermomechanically pulped Spruce fibre yielded WPG's of 15% (GMA) and 0% (AGE) under the same reaction conditions. In addition, the use of hydroquinone as an inhibitor of polymerisation yielded variable results. The observed WPG's obtained were found to be strongly influenced by the clean-up procedure used at the end of the reaction. The results suggest that, under the conditions used in this study, no reaction with the wood hydroxyl groups is occurring but that homopolymerisation of the epoxides is responsible for the observed data.     

Synthesis and characterization of iminothiazole bearing polyphenol with adjustable white–yellow photoluminescence color

A new kind of thiazole based Schiff base, 2-[(benzothiazol-2-ylimino)methyl]phenol (2HBABT), was synthesized and then converted to its oligomer structure (O-2HBABT). Structural characterizations were made by Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), size exclusion chromatography (SEC), and scanning electron microscopy (SEM) techniques. Optical properties were investigated by UV–vis and fluorescence analyses. Optical band gaps (E_g) were determined by absorption edges. Photoluminescence (PL) properties were determined in solution forms. Changes in PL characteristics in different solvents and applied excitation wavelengths were examined. O-2HBABT showed white and yellow emission colors in DMF by changing of applied excitation wavelength. Solid state electrical conductivities were measured by four-point probe technique. Cyclic voltammetry (CV) measurements were carried out and HOMO–LUMO energy levels and electrochemical band gaps (E′_g) were calculated. Thermal data were obtained by TG-DTA and DSC techniques.     

Nanoclay assisted strengthening of the fiber/matrix interface in functionally filled polyamide 6 composites

This study describes the contribution of a nano-filler, i.e. an organically modified layered silicate, in respect of the fiber/matrix interfacial shear strength (IFSS) of a short glass fiber reinforced and functionally filled polyamide 6, given an exfoliated nanocomposite morphology. Apparent IFSS values are determined using a continuum micromechanical method. Polymer chains in the nanoconfined environment of an exfoliated clay nanocomposite are found to crystallize preferentially in the form of a specific crystalline phase with increased degree of crystallinity. Strong dependence of IFSS on polymer crystallinity is found which is related to enhanced shrinkage stresses associated with increased degree of crystallinity.     

Measurements of Microhardness and Thermal and Electrical Properties of the Binary Zn-0.7wt.%Cu Hypoperitectic Alloy

Zn-0.7wt.%Cu hypoperitectic alloys were directionally solidified upwards with different temperature gradients (3.85 K/mm to 9.95 K/mm) at a constant growth rate (0.042 mm/s), and with different growth rates (0.0083 mm/s to 0.436 mm/s) at a constant temperature gradient (3.85 K/mm), using a Bridgman-type growth apparatus. Measurements of microhardness of the directionally solidified samples were carried out. The dependence of micro- hardness (HV) on growth rate (V) and temperature gradient (G) was analyzed. According to these results, it has been found that, for increasing values of G and V, the value of HV increases. Variations of electrical resistivity (ρ) and electrical conductivity (σ) for cast samples with temperature from 300 K to 670 K were also measured by using a standard direct-current (DC) four-point probe technique. The variation of the Lorenz coefficient with temperature for the Zn-0.7wt.%Cu hypoperitectic alloy was determined using the measured values of electrical conductivity and thermal conductivity. The enthalpy of fusion for the same alloy was determined by means of differential scanning calorimetry (DSC) from the heating trace during the transformation from liquid to solid.     

Technical note An assessment of the geometric accuracy of remotely-sensed images

Raw digital images cannot be used as maps because they contain geometric distortions which stem from the image acquisition process. To supply the same geometric integrity as a map, original raw images must be geometrically corrected and the distortions, such as variations in altitude, and earth curvature, must be compensated for. In this Technical Note, the geometric accuracy of a SPOT P image was evaluated by comparing a ground-based reference area, with areas calculated from the image. The areas were calculated using four different methods.     

New Poly(azomethine‐urethane)s including melamine derivatives in the main chain: Synthesis and thermal characterization

Up to date, only a few kinds of poly (azomethine‐urethane)s (PAMUs) derived from aromatic hydroxy compounds were obtained and studied with thermal degradation steps. Novel PAMUs were prepared using the hydroxy‐functionalized Schiff bases derived from melamine and toluene‐2,4‐diisocyanate. Schiff base prepolymers were synthesized by the condensation reaction of melamine with 4‐hydroxybenzaldehyde and 2‐hydroxy‐1‐naphtaldehyde. Characterization was made by UV–Vis, FTIR, NMR, and SEC techniques. Thermal characterizations of the novel PAMUs were carried out by TG‐DTA and DSC techniques. Thermal decomposition steps at various temperatures were also clarified and the physical changes of the synthesized PAMUs with exposing to the thermal degradation steps were displayed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives

A new polyurethane was synthesized by condensation reaction of 2,4-dihydroxy benzaldehyde (DHB) with methylene-di-p-phenyl-diisocyanate (MDI) under argon atmosphere. The synthesized polyurethane was converted to its poly(azomethine urethane) species (MP-2AP, MP-3AP, and MP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s (PAMUs) were converted to their polyphenol species (P-MP-2AP, P-MP-3AP, and P-MP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV–vis, ¹H-NMR, and ¹³C-NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FT-IR analyses of degraded products. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities.     

Synthesis and characterization of graft copolymers of melamine: Thermal stability, electrical conductivity, and optical properties

In this study, novel three Schiff bases of melamine were synthesized via condensation reaction of melamine with salicylaldehyde, 3-hydroxybenzaldehyde, and 4-hydroxybenzaldehyde namely N,N′,N′′,-tris[(2-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (2-HPMTT), N,N′,N′′-tris[(3-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (3-HPMTT), N,N′,N′′-tris[(4-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (4-HPMTT), respectively. Then, oligo/polyphenol derivatives of these Schiff bases were obtained by grafting melamine onto oligosalicylaldehyde (OSA), oligo-3-hydroxybenzaldehyde, and oligo-4-hydroxybenzaldehyde that have generate names of poly-N,N′,N′′-tris[(2-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (P-2-HPMTT), poly-N, N′,N′′-tris[(3-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (P-3-HPMTT), and oligo-N,N′,N′′-tris[(4-hydroxyphenyl)methylene]-1,3,5-triazine-2,4,6-triamine (O-4-HPMTT), respectively. The structures of the synthesized compounds were confirmed by FT-IR, UV–vis, ¹H NMR, and ¹³C NMR techniques. The characterization was made by TG-DTA, DSC, size exclusion chromatography (SEC), and solubility tests. Electrical conductivities of the synthesized materials were measured by four-point probe technique using a Keithley 2400 electrometer showing that the synthesized oligo/polyphenols have higher electrical conductivities than the monomeric Schiff bases. Also considerable increases in the conductivities were observed when they were doped with iodine as a doping agent. The order of increase rates of the conductivities were found as follows: 2-HPMTT > P-2-HPMTT > P-3-HPMTT > 3-HPMTT > 4-HPMTT > P-4-HPMTT. Additionally, the optical band gaps (E_g) were calculated by using the absorption spectra and found to be 2.78, 2.17, 3.58, 3.30, 4.03, and 2.82 eV for 2-HPMTT, P-2-HPMTT, 3-HPMTT, P-3-HPMTT, 4-HPMTT, and O-4-HPMTT, respectively.     

Synthesis and characterization of aromatic and aliphatic ether bridged polymers containing carbazole moieties

In this study, the polymers were synthesized ether bridged containing carbazole moieties via HBr elimination. Also, these polymers include the aliphatic chains at the different lengths and aromatic groups in their structures. However, the polymers were characterized by FT-IR, NMR and UV–vis spectroscopy, and their thermal stabilities were determined via TGA measurements. Fluorescence measurements were performed using N,N′-dimethyl formamide solutions and also, the optimization of the concentrations to obtain maximal emission intensity was investigated in N,N′-dimethyl formamide. The morphologic properties of the polymers were investigated at different particle sizes by using Scanning Electron Microscopy (SEM). Additionally, the number average molecular weight (M_n), weight average molecular weight (M_w) and polydispersity index (PDI) values of the polymers were determined by size exclusion chromatography (SEC) technique. Resultantly, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties.     

Evaluation of sorption properties of Turkish tarhana powder

Moisture adsorption isotherms of commercial tarhana powder, a popular Turkish food used in soup making, were determined at 10 °C, 20 °C and 30 °C. Gravimetric static method was applied at 0.08–0.92 water activity range. The data was fitted to Guggenheim-Anderson-deBoer(GAB), Oswin, Hendersonand Brunauer-Emmett-Teller(BET)equations. Mean relative deviation (%E) was used to compare the goodness of fit. The BET was found the best equation for the range of water activity 0.08–0.58. The GAB equation was found adequate and gave similar result with the Oswinequation at 10 °C and 20 °C, while the Oswinequation was better for characterizing the adsorption behavior of tarhana sample for the whole range of temperature and water activity studied.