Effect of modification with nitrocellulose and phenol formaldehyde resins on some performance characteristics of rubber seed oil alkyds

Three alkyd samples each of 50% oil length were prepared with phthalic anhydride, glycerol and crude rubber seed oil (I), refined rubber seed oil (II) and methyl esters of rubber seed oil (III) employing the alcoholysis method. All the alkyds were processed to acid value below 10 mg KOH/g. The alkyd samples were blended with nitrocellulose and phenol formaldehyderesins in different proportions. The performance of the blends in terms of drying schedule, chemical resistance and pencil hardness was determined. The blends were observed to show improved properties to a substitution level of 40% rubber seed oil alkyd in the blend. The resistance of the blends to different service media was found to be better than the rubber seed oil based alkyd resin

Monodisperse Polystyrene Microspheres: Studies on the Effects of Reaction Parameters on Particle Diameter and Colloidal Stability

The synthesis of highly monodisperse polystyrene (PS) microspheres via surfactant-free emulsionpolymerization process was successfully carried out. Various reaction conditions such as initiatoramount, monomer amount, reaction temperature and stirring speed were varied with a view tostudying the effects of these polymerization parameters on the particle diameter and colloidalstability of the synthesized PS microspheres. Microscopic analysis revealed that the as-synthesizedparticles are spherical in shape without any form of agglomeration. Thermo-gravimetric analyzer(TGA) analysis revealed that the prepared PS sample completely degrades at 465 °C. DLS analysisshowed a reduction in the average particle diameters of the as-synthesized PS microspheres as thereaction temperature, stirring speed and initiator amount increased, whereas an increase in averageparticle diameter was observed with increased monomer amount. Zeta-potential values rangingfrom –30.10 mV to –39.50 mV, which is indicative of stable colloidal dispersion of particles, wereseen for all the synthesized PS samples. Keywords: Monodisperse; Colloidal Stability; Polystyrene Microspheres; Average ParticleDiamete

Generation of Highly Ordered 3D Vivid Monochromatic Coloured Photonic Crystal Films Using Evaporative Induced Technique

Structural coloured crystal films have attracted immense attention because of numerous applications like optical sensing, anti-counterfeiting and photonic fabrics.  Herein, we successfully generated highly periodic three-dimensional (3D) monochromatic structural crystal films with brown, turquoise, blue and yellow colourations from as-synthesized poly(styrene-methyl methacrylate-acrylic acid) or P(St-MMA-AA) colloidal latex via the evaporative induced self-assembly technique. The colours were controlled through the modulation of their crystal lattice by varying their microspheres diameter from 180 nm, 120 nm, and 260 nm to 150 nm. Scanning electron microscope and atomic force microscope (SEM/AFM) analyses showed that the photonic crystal particles readily assembled into an impeccable closely-packed three dimensional (3D) ordered hexagonal structure with multiple monolayer arrangements. Transmission electron microscope (TEM) analysis revealed that the synthesized P(St-MMA-AA) colloidal particles have a core-shell morphology. The ability to deliberately fabricate photonic crystals by synthesizing polymer colloidal particles with a specific desired size for the fabrication of monochromatic colours would be very useful in the field of optical sensing. Keywords: core-shell; crystal films; photonic crystal films; monochromati

Binding of nickel and zinc ions with activated carbon prepared from sugar cane fibre (saccharum officinarum L.)

Activated carbon was prepared from sugar cane fibre by carbonizing at 500 oC for 30 minutes. This was followed by activation with ammonium chloride. The activated carbon was characterised in terms of pH, bulk density, ash content, surface area and surface charge. Equilibrium sorption of nickel and zinc ions by the activated carbon was studied using a range of metal ion concentrations. The sorption data was observed to have an adequate fit for the Langmuir isotherm equation. The level of metal ion uptake was found to be of the order: Ni2+ > Zn2+. The difference in the removal efficiency could be explained in terms of the hydration energy of the metal ions. The distribution coefficient for a range of concentration of the metal ions at the sorbent water interface is found to be higher than the concentration in the continuous phase. KEY WORDS: Nickel, Zinc, Activated carbon, Sugar cane fibre, Langmuir isotherm  Bull. Chem. Soc. Ethiop. 2007, 21(1), 151-156

Characterization of avocado pear (Persea americana) and African pear (Dacryodes edulis) extracts

The oil from edible avocado pear (Persea americana) and African pear (Dacryodes edulis) were extracted with chloroform. The oil were characterized for melting point, refractive index, relative viscosity, free fatty acids, saponification value, iodine value, acid value and percentage unsaponifable matter. The percent oil content in the fruit pulp was determined. The oil content of avocado pear was 9.1% while that of African pear was 23.2%.The physico-chemical characteristics and fatty acidcomposition of these oils, suggest some industrial potentials

Preliminary investigation of chemical fractionation and heavy metal accumulation in plant maize (Zea mays) grown on chromated copper arsenate (CCA) contaminated soil amended with poultry droppings

Poultry droppings used as soil amendments and a sequential chemical speciation (six steps) procedure were used to predict the uptake of Cr, Cu and As by maize (Zea mays) plant in chromated copper arsenate (CCA) contaminated soil. A pot experiment containing contaminated soil samples to different percentage levels of amendments and control (no amendment) was set up. The initial concentration of Cr, Cu and As in the contaminated soil sample were established. The six fractions based on sequential extractions were also established. The distribution patterns of the metals based on their mobility factor Mf showed values high enough to predict high lability and bioavailability for arsenic, moderate forchromium and low for copper. The amendment, an energy-rich source substance enhanced mobility and bioavailability of the metals and their subsequent uptake and accumulation in the maize plant. This led to a cleanup at 20% amendment of As (20.6%), Cr (2%), and Cu (17.1%) after a period of twenty days. These figures are impressive considering the fact that the increase in pH occasioned by the poultry dropping amendment must have bound the metals

Extraction and Physiochemical Characterization of Oils Obtained from Selected Under-Utilized Oil Bearing Seeds in Nigeria

The oils extracted from selected underutilized seeds in Nigeria; Rubber seeds (RS), African pear seeds (APS) and Cotton seed (CS) using n-hexane were analyzed for their physico-chemical properties viz: melting point, relative viscosity, free fatty acids, saponification value, iodine value, acid value, percentage unsaponifable matter, ester value and heat of combustion, using standard methods. The % oil contents in the seeds were determined to be 42.967 ± 0.59%, 19.427 ± 0.13% and 35.433 ± 0.86% for RS, APS and CS respectively. The extracted oils were liquids at room temperature with oil extracts from APS and CS having pleasant odour with light green and golden brown colour respectively, however oil extract from RS had an unpleasant smell with brownish yellow colour. There was significant difference in the physiochemical properties investigated. The acid value ranged from 6.840 to 32.000 mg KOH/g, the saponification values were high ranging from 173.115 to 185.333 mg KOH/g. The iodine value of (RSO), (139.703 g I2/100g) classified it as a semi - drying oil. The peroxide value of RSO (14.300 mequiv O2/kg oil) falls above the Standard  Organization of Nigeria (SON) recommended peroxide value (10 mequiv O2/kg oil) for edible oils and its free fatty acid (16.096 %) is also above the recommended 5% which makes it non-edible oils. The physicochemical properties of the oils suggest that they exhibit edible and industrial  potentials. Keywords: African Pear, Cotton, Oil, Rubber, See

Enhancing the quality of alkyd resins using methyl esters of rubber seed oil

Purpose: Alkyd resins constitute a very high proportion of conventional binders used in surface coatings. In order to enhance the quality of these alkyd resins methyl esters of rubber seed oil (MERSO) were used in the preparation of the resins. Methods: MERSO were obtained by in-situ alcoholysis of rubber seed. Alkyd resins having oil lengths of 45, 50 and 55% were prepared with MERSO, phthalic anhydride and glycerol using alcoholysis method. Lead (II) oxide and xylene were used as catalyst and refluxing solvent, respectively. The physico-chemical characteristics of the MERSO and the resins obtained were compared with the corresponding value of rubber seed oil (RSO) and its alkyd resins. Chemical resistance of the alkyd resins was also determined. Results: The acid value of the finished alkyd resins depends on the rate and extent of esterification. Iodine value of the alkyd shows that the level of unsaturation depends on the oil length of the resins. The free fatty acid (FFA) value (1.99%) of the MERSO was much lower than that of the RSO (9.54%). This supports the choice of methyl ester as a preferred alternative to the use of the raw RSO in alkyd resin preparation. All the alkyd samples were fairly resistant to brine, acid and water but poorly resistant to alkali. However, the MERSO alkyds were observed to have a better resistance than the RSO alkyd resins. The scratch/gouge pencil hardness shows that the hardness of the alkyd films decreases with the oil length. Keywords: Alkyd resins, rubber seed oil, methyl ester. > Tropical Journal of Pharmaceutical Research Vol. 3 (1) 2004: pp. 311-31

Evaluation of the Effect of Temperature on the Stability of Metal Soaps of Dicarboxylic Acids

The thermal stability of calcium and zinc dicarboxylates was studied. The kinetics of the decomposition was studied thermogravimetrically at various temperatures. The rates of the first stage decomposition were used to assess the effect of temperature on the susceptibility of the metal soaps of dicarboxylic acids to decomposition. Although the values of the rate constant for the decomposition of the soaps were about the same order of magnitude (10-1s-1), the soaps of glutaric acid were relatively more stable than the soaps of succinic acid. The values of the rate constant were also observed to be temperature dependent. The enthalpy, entropy and free energy of activation for the decomposition of the metal dicarboxylates were also determined. The thermodynamic values obtained showed that the system is exothermic and that the reaction process is not a spontaneous one. @JASE

PRELIMINARY INVESTIGATION OF THE MUCOADHESIVE PROPERTIES OF THERMALLY MODIFIED MUCIN ON METRONIDAZOLE TABLETS

Objective: To determine the effect of thermal treatment of mucin on the mucoadhesive and tablet parameters of metronidazole tablets. Methods: Mucin was extracted from the giant African snails (Archachatina maginata) by differential precipitation using acetone, air-dried and pulverized. Modification of the mucin powder was carried out using a regulated water bath at 60 and 100 °C and at varied times of 1 and 12 h and a micro-wave oven at varied wattage (100-600 W) and time. Ten batches of metronidazole tablets (A1-A10) were prepared with the modified mucin by direct compression. Their granules were evaluated for flow properties and the tablets for weight uniformity, crushing strength, friability, drug content and in vitro studies. Tablet mucoadhesion was determined using the mass flow rate method. Results: Granules of all the batches exhibited good flow characteristics with their angles of repose<30 °. Tablets formulated passed the weight variation test with hardness values above 4.0 kp and friability of 1.10-1.85 % while the content of active drug met official compendial requirements. Tablets of treated mucin at 60 °C for 1 and 12 h gave mucoadhesion values of 1.80 g/sec This value was higher than those of the unmodified mucin tablets which gave 0.70 g/sec. Tablets of micro-wave treated mucin gave mucoadhesion values of 1.0-1.30 g/sec, which were also higher than that of the unmodified mucin Conclusion: The study shows that modification of mucin at 60 °C for 1 and 12 h may be considered as the most promising among the batches tested as their tablets had improved mucoadhesive properties compared to the unmodified mucin