Synthesis and evaluation of tetra(2,7-octadienyl) titanate as a reactive diluent for air-drying alkyd paints

Environmental regulations are forcing the reformulation of many decorative and protective coatings systems. In particular, air-drying solventborne alkyd paints need to meet increasingly stringent emission limits and often must be reformulated with suitable exempt solvents or reactive diluents to achieve volatile organic compound (VOC) reduction. In the research summarized in this article, a new reactive diluent, tetra(2,7-octadienyl) titanate, was synthesized and evaluated in alkyd formulations for VOC reduction and property enhancement. A soy-based long-oil alkyd resin; a soy-based high-solids, long-oil alkyd resin; and a linseed-based, high-solids long-oil alkyd resin were evaluated in combination with the new reactive diluent at weight percentages ranging from 10% to 50%. Characterization included measuring viscosity, film dry times, and film performance of the reactive diluent formulations in comparison to neat alkyd resins used as control. The tetra(2,7-octadienyl) titanate formulations consistently exhibited reduced viscosities and dry times as a function of concentration. The resulting films were harder and more thoroughly cured than the control systems.     

Optimization of some parameters of stirred mill for ultra-fine grinding of refractory Au/Ag ores

In this study, optimization of some parameters of stirred mill on ultra-fine grinding of refractory Au/Ag ores was performed. A three-level Box-Behnken design combining a response surface methodology (RSM) with quadratic programming (QP) was employed for modelling and optimization of some operating parameters in ultra-fine grinding. Grinding tests were carried out in a laboratory scale pin-type vertical stirred mill. The relationship between the response, i.e. d₈₀ size, and four grinding parameters, i.e. ball diameter, grinding time, ball charge ratio and stirrer revolution was presented as empirical model equations. Analysis of variance showed a high coefficient of determination value (R² = 0.9698), thus ensuring a satisfactory of the second-order regression model with the experimental data.The model equations were then optimized using the quadratic programming method to minimize for d₈₀ size within the experimental range studied. The optimum conditions were found to be 1.61 mm for ball diameter, 11.50 min for grinding time, 80% for ball charge ratio and 745 rpm for stirrer revolution for this grinding process.In order to verify the improvement of grinding performance using the optimal level of control factors three verification experiments were conducted, and the results for d₈₀ was 3.37 μm, which were smaller than those obtained in the initial tests.     

EXTRACTION OF TITANIUM(IV) FROM AQUEOUS HYDROCHLORIC ACID SOLUTIONS INTO ALAMINE 336-M-XYLENE MIXTURES

Extraction of Ti(IV) from its aqueous hydrochloric acid solutions into organic Alamine 336-m-xylene systems was investigated. Extraction experiments were conducted with three different initial metal concentrations of 1, 3, and 6 mg/mL, each at three acidic molarities of 1, 5, and 10 M. It was observed that the extractability of Ti(IV) increases with increasing acidic molarities. Alamine 336 diluted with m-xylene was found to be a suitable extractant for Ti(IV) across this acidic range. In parallel, a mathematical model was developed to correlate metal extractability and Alamine 336 volume content. Optimal Alamine 336 contents were estimated for single-stage extraction.     

A non-contact method for part-based process performance monitoring in end milling operations

Surface response to excitation (SuRE) method was originally developed for structural health monitoring (SHM) applications. SuRE was used to evaluate the performance of completed milling operations. The method generates surface waves on the plate and studies the spectrum changes at selected points to detect defects and change of compressive forces. In this study, the length, depth, and width of a slot were changed step by step. The surface of the aluminum plate was excited in the 20–400 kHz range with a piezoelectric element. A laser scanning vibrometer was used to monitor the vibrations at the predetermined grid points after the dimensions of the slot were changed methodically. The frequency spectrums of measured vibrations were calculated by using the Fast Fourier Transformation (FFT). The sums of the squares of the differences (SSD) of the spectrums were calculated to evaluate the change of the spectrums. The SuRE method was able to determine if the dimensions were changed in each case at all the selected points. The scanning laser vibrometer is not feasible to be used at the shop floor. However, the study demonstrated that a piezoelectric element attached to any of the grid points would be able to evaluate the completed machining process.     

Non-isothermal kinetics of pyrolysis of Turkish petroleum pitches

Non-isothermal thermogravimetric data of two Turkish petroleum pitches were used to evaluate kinetic parameters of pyrolysis reactions. The article reports the application of Ozawa–Flynn–Wall model to deal with non-isothermal TG data for the evaluation of the activation energy corresponding to the pyrolysis of two different petroleum pitches. Non-isothermal kinetic studies of pyrolysis of the pitches based on the TGA measurements at different heating rates resulted that average activation energy of pyrolysis of pitch B (213 kJ/mol) was higher than that of average activation energy of pitch A (186 kJ/mol). Reaction orders of pitch A and pitch B were calculated as 0.6 and 0.9, respectively.     

In situ X-ray diffraction of the early stages of the crystallization of Fe80B20

A new technique has been used for the early stages of crystallization of amorphous materials, like metallic alloys. In situ X-ray diffraction has been performed during the early stages of crystallization of Fe₈₀B₂₀. The samples are resistively heated to 600°C in a customized vacuum chamber. A programmable charge-coupled device detector records simultaneously the evolution of the three phases: -Fe, Fe₃B and Fe₂B in the minute scale. This is the first in situ X-ray diffraction study of this system in these temperature and time scales. Interesting behaviours have been seen: appearance and disappearance of phases, -Fe supersaturation solution in boron (found for the first time in this compound), and migration of B out of the -Fe matrix. The two-dimensional diffraction pictures show topography irregularities indicating crystallite inhomogeneties.     

Recognition of chatter with neural networks

Chatter deteriorates surface finish, reduces tool life, and damages machine tools. A chatter development prediction procedure is proposed for the cylindrical turning of long slender bars. The procedure uses two synthetically trained neural networks to recognize the harmonic acceleration signals and their frequency, and based on these observations, the future vibration characteristics of the system are estimated. The developed neural networks are capable of identifying 98% of the harmonic signals with over 90% certainty and estimate their frequencies with less than ±5% error from very short data sequences (only 11 sampled points). The accuracy of the neural networks is equivalent to time domain time series method based approaches; however, the proposed procedure can be implemented very quickly by using commercially available neural network hardware and software, and can use the new neural network chips to make the estimations very quickly by using parallel processors. The validity of the chatter prediction procedure is also demonstrated on the experimental data.