A new approach to investigate scratch morphology and appearance of an automotive coating containing nano-SiO2 and polysiloxane additives

Attempts have been carried out to verify whether gonio-spectrophotometry could be utilized as a new scratch testing approach to investigate scratch morphology and its effect on appearance of an acrylic-melamine clearcoat separately containing nano-silica or polysiloxane additives. The results of gonio-spectrophotometry/colorimetry illustrated that this new approach is capable of differentiating between plastic and fracture types scratches. Furthermore, this approach was found to be suitable for analyzing the self healing abilities of such coatings. The accuracy and reproducibility of such results were checked against the results of scanning electron microscope (SEM) and illustrated great potential as a new approach for such studies.     

Correlation between the BYK's balance index and the appearance of visually assessed achromatic automotive finishes

In the present investigation, the effectiveness of “Structure Balance Index” in correctly predicting the appearance of visually assessed achromatic automotive finishes was evaluated. For visual evaluation, the pair comparison method utilizing 16 observers assessing in a light cabinet, having a 45/0° viewing geometry, was used. The statistical results show that the observer repeatability and reproducibility were acceptable. However, evaluation of the Balance index (B) illustrates that the tolerance regions of green, yellow and red in the Balance chart of the presently prepared achromatic samples differed from the BYK's originally defined regions when compared to visual assessments. This means that this index cannot be extended to all lightness levels. Furthermore, such acceptability regions of green, yellow and red are not symmetrical enough for different lightness to promote the balance index for general use. Instead, this index can be regarded as a secondary fine-tuning corrector of Wd and LW parameters.     

Novel techniques to investigate the impact of cellulose esters on the rheological properties and appearance in automotive basecoat systems

The viscous response of a coating formulation changes over several orders of magnitude after application onto a substrate. Furthermore, the performance and application attributes for a refinish basecoat formulation are slightly different from those of an OEM basecoat. The absence of a high temperature baking step during the refinish process necessitates that the paint exhibit very good antisag behavior as well as quick ‘dry to touch’ without compromising the flow and leveling properties of the coating as it dries. As most paint formulations are multicomponent in nature, it is always a challenge to precisely measure the impact of specific formulation components on the collective performance attributes of the applied coating. In this work, the focus has been to develop novel techniques that can be used to demonstrate a more quantitative measure of some of the performance attributes that rheological additives like cellulose esters can provide to automotive coatings. A series of pigmented basecoat formulations were prepared which contained cellulose acetate butyrates (CABs) of varying molecular weights at different levels based on the total solids of the coating formulation. The nonvolatile content of the formulations was also varied. The viscoelastic behavior of a typical automotive basecoat formulation during the drying process was then investigated using a novel rheological technique. Complex viscosity data (including storage and loss moduli as well as tan delta) were determined as a function of drying time and then compared to the macroscopic properties typically associated with a coating film as it dries. Thermogravimetric analysis (TGA) was also used to correlate the rheology of the metallic basecoat formulations with drying behavior of the coating. The final appearance of the coating was investigated by several microscopic techniques such as Laser Scanning Confocal Microscopy, Scanning Electron Microscopy, Atomic Force Microscopy, and Surface Profilometery, and attempts were made to correlate bulk measurements like ‘flop index’ with the microstructure of the coating. Presented at the 2006 FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

A new approach to characterize scratch and mar resistance of automotive coatings

Mar damage is a major customer concern of the automotive coatings industry. Our study of mar performance can be separated into two distinct areas, a detailed understanding of the damage formation mechanism, and an investigation of the relationship between the damage morphology and appearance. We have developed a nanoscratch technique that can measure important physical quantities, such as penetration depth, normal force and tangential force during the formation of the scratch. Mar resistance of three coatings was evaluated and compared based on the damage mechanisms: plastic flow and fracture. The different deformation mechanisms result in different damage morphologies and a corresponding change in visual impact of the scratch. Statistical surveys of appearance of well-defined scratches indicate that in very short observation times, scratches where fracture has occurred are much more visible than those made by plastic deformation alone. However, with sufficient time and strong illumination a significant percentage of observers could see plastic deformation as well.     

The interpretation of GLC triglyceride data for the determination of cocoa butter equivalents in chocolate: A new approach

A new approach to interpret triglyceride data obtained by gas liquid chromatography (GLC) in order to determine cocoa butter equivalents (CBE) in chocolate is described. The approach is based on the known straight line relationship which exists between the C₅₀ and C₅₄ triglycerides of cocoa butter of different origins and the realization that, for currently available CBE conforming to CAOBISCO’s criteria, a similar band relationship exists. The technique described enables the quantity of unspecified CBE in a chocolate containing an unknown cocoa butter to be determined to an accuracy of ±1.5% when present in chocolate at the 5% level. Nut oils (almond, walnut or hazelnut) are sometimes present in mainland European chocolates and, should CBE also be present, it is possible to calculate the combined percentages of nut oil and CBE in the chocolate. The method of interpretation described is not dependent on a particular GLC technique for determining triglycerides. Interpretation of other laboratories’ results obtained using different GLC instruments and procedures has shown that the method enables any CBE present in the fat under examination to be determined accurately. The method compensates for variations in the composition of CBE and for the differences between cocoa butters of different origin. A detailed knowledge of CBE compositions is not required and only a few cocoa butter/CBE standards are necessary. The method described is graphical, enabling small laboratories not equipped with microcomputers to utilize the method. The calculation can, however, be programmed for a computer.     

The effects of acid rain on the appearance of automotive paint systems studied outdoors and in a new artificial weathering test

A study was performed exposing seven automotive OEM coatings (base coat/clear coat paint systems) outdoors in Jacksonville and to different variants of the acid dew and fog (ADF) test, a new approach to simulating the worst case of the weather conditions in harsh urban and industrial environments. Varying the climatic conditions and the severity of the simulated acid precipitation, a certain variant of the ADF test was found to show a satisfying practice correlation. Profilometric and chemical analysis revealed that the coatings differ in the rate of photodegradation after an acid attack due to the penetration of acid solution.     

A new approach to evaluate kinetic parameters and mass transfer coefficients in continuous stirred tank reactors. Application to antibiotic separation

A new method is proposed to evaluate kinetic parameters and mass transfer coefficients for adsorption processes carried out in continuous stirred tank reactors. This method, employing a biphasic model, does not linearize nonlinear solute concentration versus time data, nor does it assume the existence of equilibrium in a typical nonequilibrium situation as is currently done. For a nonlinear adsorption isotherm, the coupled differential equations need to be solved numerically, but using an elegant analytical solution it is possible to determine rate constants and mass transfer coefficients in the case of nonlinear kinetics with a linear adsorption isotherm. This solution (biphasic model, linear isotherm) is obtained and compared with solutions incorporating (i) a linear model (linear isotherm) and (ii) a numerical solution (nonlinear isotherm) for recovery of the antibiotic novobicoin in stirred tank reactors. For novobiocin adsorption versus time data, use of the biphasic model results in a lower mean percentage error than either the linear model or the numerical simulation; further, it provides a far superior fit of short-time adsorption behavior. Hence, we strongly advocate that the biphasic model be routinely employed along with linear models and numerical simulations of Langmuir/Freundlich isotherms for interpretation of adsorption data.     

A new approach to the solubility in aqueous salt solutions

The paper develops a new approach to the analysis of a solid–liquid phase diagram in terms of the chemical potentials of the single phases. The approach stems from the basic hypothesis that chemical potentials between different phases are equal at equilibrium. To make the idea operative, the mathematical dependence of the pertinent chemical potentials on the temperature and the mass fraction is determined by means of Aspen Plus; for definiteness a sodium chloride solution is examined. The phase diagram is established and the analytical properties of the curve are obtained. Moreover, the functional dependence of the mass fraction on the temperature at the freezing point is determined. The satisfactory agreement with new experimental data proves the validity of the procedure. The methodology so developed, provides an improved and rigorous mathematical overview for the analysis of phase diagrams. The approach is likely to be applicable to the investigation of solutions with several constituents or alloys.     

A new approach to the identification of transitions in fluidized beds

Earlier work with silica sand has indicated that in a system where a bed of particles is aerated at increasing superficial velocities, the von Neumann ratio, T, based on the bed pressure drop, may be useful in identifying both minimum fluidizing velocity, U_mf, and minimum bubbling velocity, U_mb. Plots of T^− 1 against superficial velocity exhibited significant change at velocities consistent with those where bed height first changed (onset of fluidization), the packed bed pressure drop underwent a transition from a monotonic linear function of superficial velocity to a steady value (onset of fluidization) and standard deviation of bed pressure drop rapidly increased (onset of bubbling). However, the suggestion that T might be a valid indicator of U_mf was supported by data for a single material only. In this paper additional data is presented that supports the suggestion that T might be useful in measuring U_mf, and also provides additional evidence for the potential utility of T in determining U_mb. In principle, this would allow a single campaign of pressure measurements to be used to identify both U_mf and U_mb.     

A new approach to testing materials in the NBS smoke chamber

The standard NBS/Aminco smoke test chamber is critically examined from the point of view of repeatability and reproducibility of the apparatus itself. Individual components contributing to the overall determination are examined and suggested lines for improvement are made which should result in more consistent results. Problems associated with the presentation of results are discussed and a new approach which includes time-weighted data is proposed. This attempts to consider the rate dependence of smoke production in one calculated figure rather than isolated observations such as maximum optical density. Utilizing the NBS/Aminco chamber, a novel procedure for determining the smoke evolution characteristics of materials has been developed which can be considered to simulate more closely the progress of thermal degradation that a material undergoes in a real fire.     

A new method to determine the microbial kinetic parameters in biological air filters

This paper presents a new method to determine kinetic parameters of the biodegradation of various pollutants in a biofilter. Toluene, a readily biodegradable volatile organic compound, and methane, a hydrocarbon and a greenhouse gas, have been chosen as the target pollutants. The new protocol utilized biomass immobilized on bed pellets; these directly sampled from a continuous steady-state biofilter. The comparison of this method with the conventional experimental protocol utilizing micro-organisms suspended in a liquid medium was made using the pollutant toluene. Indeed, with both methods, the kinetic parameters have been evaluated by following the microbial growth in batch, thermostated reactors, using determined amounts of pollutant substrate. This experiment has confirmed the pertinence of the new procedure. The interesting features of the new method are that: (1) it is easy to operate (no preliminary treatment of the bed samples) and (2) it provides reproducible parameters that represent the real biofilter case more adequately than liquid cultures. In addition, modeling of the experimental specific growth rates in the case of toluene has shown that the values obtained with the use of solid extracts can be correlated by a Haldane's formulation, where , , and . The maximum specific growth rate was reached for an initial concentration of toluene near . The determination of the experimental specific growth rates of micro-organisms in the methane biofilter has also been performed. This study allowed highlighting two methane concentrations’ ranges: from 1000 to 14 500 ppmv and from 14 500 to 27 000 ppmv. For the first range, the Monod model proves to be suitable with the kinetic parameters: and . For the second range, neither the Monod nor the Haldane's formulation could directly be used. However, a mathematical adjustment of the Monod model allows to find kinetic parameters and . The biomass yields for the tested methane concentrations have also been determined and showed two different tendencies, depending on the same two ranges. For the first range of methane concentrations, the biomass yield was quite constant with an average value around while for the second range, it could be approached by a polynomial second-order regression. The maximum value of the biomass yield obtained on the second range was at a methane initial concentration of 20 000 ppmv.     

Application of the taguchi approach to investigate the effects of clay content and saponification parameters on the tensile properties of poly(vinyl alcohol)/clay nanocomposites

Poly(vinyl alcohol) (PVA)/montmorillonite nanocomposites were prepared via solution polymerization. The nanocomposites were formed either by first hydrolyzing poly(vinyl acetate) (PVAc) to PVA and then preparing the PVA/clay, or by initially preparing PVAc/clay and then hydrolyzing the matrix to PVA. The morphology of the nanocomposites was examined by X‐ray diffraction and transmission electron microscopy, which suggested the proper dispersion of silicate layers within the PVA matrix. The influences of some variables including method of preparation, clay content, and time and temperature of saponification on the tensile properties (elastic modulus, stress and elongation at break) of the nanocomposite samples were investigated by using the Taguchi experimental design approach. The results indicated that the tensile properties of the nanocomposites improved as clay content, and the temperature and time of saponification increased. Effect of each factor on the ultimate properties of as prepared nanocomposites are discussed in detail. The analysis of variance (ANOVA) showed that the method of preparation did not influence the ultimate tensile properties of the nanocomposite samples. Thermal degradation of the nanocomposites was studied by thermogravimetric analysis, which showed that their thermal stability was higher than that of virgin polymer. J. VINYL ADDIT. TECHNOL., 19:276–284, 2013. © 2013 Society of Plastics Engineers     

A new technique to reduce the radioactivity of fly ash utilized in the construction industry

High volume utilization of industrial wastes and by products is the solution for high disposal costs. Acceptable radioactivity levels in addition to other environmental factors is a key factor for safe utilization of wastes and byproducts of coal burning power plants. In general the radioactivity levels of most fly ashes are similar to natural materials. For higher radioactivity fly ash the radioactivity values must be reduced to acceptable limits. This can be done by mixing the fly ash with less radioactive natural materials. In this study a new technique involving the use of snow as an additive to the compaction water of fly ash is presented. Fly ash at optimum water content, and fly ash with additional 10% by weight snow are compacted, hermetically sealed to allow for equilibrium of ²²⁶Ra and ²³²Th with their decay products and cured for 28 days at the curing room. Radioisotope activity analysis are conducted with a gamma analyst integrated gamma spectrometer. The activities of ²³⁵U, ²²⁶Ra, ²³⁸U, and ²³²Th of the fly ash and snow-added fly ash samples compacted at optimum moisture content are determined. The control samples revealed radioactivity values above UNIPEDE maximum allowable limits. Addition of snow caused a decrease of 31-42% in the radioisotope activity levels to that of control samples in Bq kg⁻¹.The decrease in radioactivity is linked to increased void ratio after melting of ice, increased densification of matrix around the pores due to higher level of cementitious mineral formation. The decrease in the radioisotope activity levels will allow utilization of fly ash in highway embankment construction where large surface area exposure and large volume usage makes it more critical for human health. Another advantage of the developed technology is the reduction of transportation costs by more than ten per cent by using less material for construction.     

A novel approach using differential scanning calorimetry to investigate the dissolved state in aqueous solutions of polymers used for papermaking

The size and conformations of dissolved polymer molecules of polyethylene glycol (PEG) in 5% aqueous solutions were examined through the use of differential scanning calorimetry (DSC). As long as the freezable bound water is considered to be the water enclosed by the entangled polymer chains in the solution, the appearance of the characteristics of a polymer begins to occur at a degree of polymerization (DP) between 11 and 21 and is largely completed at a DP of about 50. Assuming that the peak temperature of the DSC curve for the freezable bound water indicates the size of the entangled molecular coil, the lowering of the peak temperature with a decrease of molecular weight (MW) suggests a decrease in the size of the entangled molecular coil. The linear relationship between the peak temperature and the reciprocal of the number‐average MW suggests melting point depression as a plausible mechanism for the peak temperature lowering. Mixing of two polymers with different MWs—and thus, entangled molecular coils of different sizes—causes a kind of polymer–polymer interaction and the coil sizes change as follows. If the difference in the values of the two MWs is large, the sizes of the entangled molecular coil of each MW are brought closer to each other. The extent of approach is roughly proportional to the mixing ratio. If the difference in the values of the two MWs is not large, the original entangled molecular coils disappear and a single molecular coil of intermediate size appears instead. The size of the single intermediate molecular coil varies roughly according to the simple mixing law for the values of the two MWs. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2798–2807, 2003     

A new approach to the identification of gross errors in chemical engineering measurements

This paper contributes to the problem of identification of gross errors in chemical engineering measurements. The methods hitherto suggested enable a set of quantities, suspicious as a possible source of gross errors, to be found. However, the set of suspicious quantities may be quite extensive in real problems. Described in the present paper is a new method based on the information of measurement credibility. The meaning of this term is the maximum value of a gross error that may occur in individual measurements. This method complements those developed previously and makes possible reducing the number of measured quantities which have to be checked out during the final phase of gross error elimination.     

A new approach to fluid separation modelling in the columns equipped with structured packings

An analogy between the flow patterns in real separation columns equipped with structured packing and film flow is used to develop a new modelling approach. The packing is represented as a bundle of channels with identical triangular cross section. The dimensions of the channels as well as their number are derived from the packing geometry. The channel inner surface is wetted by a liquid flowing downwards, whereas the rest of the volume is occupied by a countercurrent vapour flow. Both phases are assumed to be totally mixed at regular intervals, determined by the corrugation geometry of the packing. The mathematical model is based on a set of partial differential equations describing hydrodynamics and mass and heat transport phenomena. These equations are complemented by the conjugate boundary conditions at the phase interface. A numerical solution of the model yields velocity profiles as well as concentration and temperature fields throughout the column. The model is verified using experimental data for a binary distillation in a column equipped with Montz-Pak A3-500.     

A new Lagrangian decomposition approach applied to the integration of refinery planning and crude-oil scheduling

The aim of this paper is to introduce a methodology to solve a large-scale mixed-integer nonlinear program (MINLP) integrating the two main optimization problems appearing in the oil refining industry: refinery planning and crude-oil operations scheduling. The proposed approach consists of using Lagrangian decomposition to efficiently integrate both problems. The main advantage of this technique is to solve each problem separately. A new hybrid dual problem is introduced to update the Lagrange multipliers. It uses the classical concepts of cutting planes, subgradient, and boxstep. The proposed approach is compared to a basic sequential approach and to standard MINLP solvers. The results obtained on a case study and a larger refinery problem show that the new Lagrangian decomposition algorithm is more robust than the other approaches and produces better solutions in reasonable times.     

A new low temperature approach to developing mesoporosity in metal-doped carbons for adsorption and catalysis

Key factors in achieving effective adsorption are the size of the pores relative to those of the adsorbate molecules and often the presence of small metal particles which can confer catalytic activity. While microporous carbons are excellent adsorbents for small molecules they are not as effective for larger species. A new low temperature approach to activation using an oxygen gas pulsing technique to achieve a carbon with controllable meso/micropore structure is described which also minimises metal sintering. The porosity of the samples was analysed by nitrogen adsorption at 77 K. Microporous metal-doped ASC carbon showed significant increases in the level of mesoporosity, its mesopore volume increasing from 0.06 to 0.24 cm³ g⁻¹. However, undoped BPL carbon treated under the same conditions remained unchanged. The catalytic effect of the metals in the ASC carbon is thought to account for the observed mesopore development. At the temperatures used, a continuous oxidative activation yielded no pore widening in either carbon, suggesting that the gas pulsing method is far more effective in increasing mesopore sizes.     

A new approach to analyzing residence time and mixing in a co-rotating twin screw extruder

A series of experiments was conducted to determine what correlations exist between an experimental parameter, percent drag flow, and other parameters such as head, tail and mean residence time. Experimentation was carried out on two polymer systems, a model system of near-Newtonian fluid and a viscoelastic system of polyisoprene with several additives. To aid in the residence time analysis, data from three literature sources were cited and replotted. A family of residence time curves for a partially filled system can be combined into one curve by plotting the number of screw revolutions carrying the tracer to the extruder exit versus the percent drag flow. This method of plotting the data for each screw configuration estimates the mean residence time for any throughput and screw speed once a few data points are taken. In all four sets of experiments, the number of screw revolutions carrying the tracer to the exit decreases with increasing percent drag flow. The filled volume of the extruder was calculated from residence time data to show that percent drag flow is linearly related to extruder filled volume. When percent drag flow increased in the viscoelastic system the following results were recorded: fraction of polymer residence time spent in conveying elements increased, fraction of residence time spent in mixing elements decreased, polymer Mooney viscosity increased, number and weight average molecular weights increased and polydispersivity increased.