Material composition effect

Material Composition Effects on Choice of Processing Method..273... 

Change in feed composition. This may happen due to change in suppliers or due to introduction of reworked material. Unwanted effect on reaction products, by-products. Varying inhibitor concentrations in monomers from different vendors. Potential for runaway reaction. 

Despite the high cost of composites, the weight-saving they permit is so great that their use in trains, trucks and even cars is now extensive. But, as this chapter illustrates, the engineer needs to understand the material and the way it will be loaded in order to use composites effectively. 

The characterisation of materials is a central necessity of modern materials science. Effectively, it signifies making precise distinctions between different specimens of what is nominally the same material. The concept covers qualitative and quantitative analysis of chemical composition and its variation between phases the examination of the spatial distribution of grains, phases and of minor constituents the crystal structures present and the extent, nature and distribution of structural imperfections (including the stereological analysis outlined in Chapter 5). 

Typical S-N (stress versus number of cycles) curves for various metals and composite materials are shown in Figure 6-4 [6-3]. The boron-epoxy composite material curve is much flatter than the aluminum curve as well as being flatter than the curves for any of the metals shown. The susceptibility of composite materials to effects of stress concentrations such as those caused by notches, holes, etc., is much less than for metals. Thus, the initial advantage of higher strength of boron-epoxy... 

N. Fried, Degradation of Composite Materials The Effect of Water on Glass-Reinforced Plastic, in Mechanics of Composite Materials, Proceedings of the 5th Symposium on Naval Structural Mechanics, Philadelphia, Pennsylvania, 8-10 May 1967, F. W. Wendt, H. Liebowitz, and N. Perrone (Editors), Pergamon, Now York, 1970, pp. 813-837. 

We just cannot expect situations like golf clubs and tennis rackets for all consumer products because all products do not have those same built-in characteristics of the competitive edge. When we consider a car, we must be realistic and acknowledge that the car must have a price low enough for people to afford. Think back to the days of Henry Ford he made a car that could be sold for about 250, so that everyone could afford to have one. This affordability was the real beauty of his mass-production techniques. Everyone could afford to have a car, and then almost everyone did have one. In contrast, before Henry Ford, only the rich could afford an automobile. As soon as we get to the trade-off where composite materials will effectively compete in the automotive market place, we will see tremendously broader applications, but there are problems along the way. The manufacturing cost must be improved in order for those applications to ever come about. 

This work was motivated by cracking of a thermoformed part while cooling on the mold, the complexity of the problem could be immediately appreciated since the effect was sensitive to very delicate changes in material composition. Due to coupling between the heat transfer and stress evolution, both problems were solved simultaneously ... 

When explosives of the power shown in this table are prepared, the power per unit length of the explosive cartridge is similar to that of the power of a sheathed explosive made from a PI composition. Effectively, therefore, the difference between a P2 and a P3 explosive is that the inert material in the sheath of the former is distributed uniformly through the explosive composition of the latter. For reasons of stability, however, sodium bicarbonate is no longer used instead an increase in the proportion of sodium chloride gives the required cooling effect. 

Juhasz, J.A., Best, S.M., Bonfield, W., Kawashita, M., Miyata, N., Kokubo, T. and Nakamura, T. (2003) Apatiteforming ability of glass-ceramic apatite-wollastonite — polyethylene composites effect of filler content Journal of Materials Science-Materials in Medicine, 14, 489-95. 

Hydroisomerization of n-octane over Pt-containing micro/mesoporous catalysts obtained by recrystallization of zeolites BEA and MOR was investigated in the temperature range of 200-250 °C under 1-20 bar. Composite materials showed remarkably high activity and selectivity with respect to both pure microporous and pure mesoporous materials. The effect is due to high zeolitic acidity combined with improved accessibility of active sites and transport of bulky molecules provided by mesopores. 

Physical models of fuel cell operation contribute to the development of diagnoshc methods, the rational design of advanced materials, and the systematic ophmization of performance. The grand challenge is to understand relations of primary chemical structure of materials, composition of heterogeneous media, effective material properties, and performance. For polymer electrolyte membranes, the primary chemical structure refers to ionomer molecules, and the composition-dependent phenomena are mainly determined by the uptake and distribuhon of water. 

Gao, Z.J. (1993). Effect of fiber-matrix interfacial shear strength on reliability of composite materials. Composite Interfaces 1, 481-497. 

Another important factor is the thermal stability and heat of decomposition of the oxidizer. Potassium chlorate mixtures tend to be much more sensitive to ignition than potassium nitrate compositions, due to the exothermic nature of the decomposition of KCIO 3. Mixtures containing very stable oxidizers - such as ferric oxide (Fe 2O 3) and lead chromate (PbCrO 4) - can be quite difficult to ignite, and a more-sensitive composition frequently has to be used in conjunction with these materials to effect ignition. 

A second type of behavior existing in the PLZT s is the linear (Pockels) effect which is generally found in high coercive field, tetragonal materials (composition 3), This effect is so named because of the linear relationship between An and electric field. The truly linear, nonhysteretic character of this effect has been found to be intrinsic to the material and not due to domain reorientation processes which occur in the quadratic and memory materials. The linear materials possess permanent remanent polarization however, in this case the material is switched to its saturation remanence, and it remains in that state. Optical information is extracted from the ceramic by the action of an electric field which causes linear changes in the birefringence, but in no case is there polarization reversal in the material. 

Advanced Composite Materials-Environmental Effects, ASTM STP 658, ed. Vinson, J. P., Philadelphia, American Society for Testing and Materials, (1978)... 

Early work using microwaves as a diagnostic tool relied upon measuring a secondary effect of the dielectric properties of the material under interrogation, i.e., reflection, absorption and transmission. The two fundamental microwave parameters, e and e" are related to the food or material composition. These two fundamental parameters also determine the reflection, absorption and transmission of the materials exposed to a microwave signal. Thus by measuring the amplitude and phase of the reflected or transmitted wave, or the characteristics of absorption of a wave through the material, one is able to empirically establish a relationship to the constituency of the product. 

Unlike classical analytical spectroscopy performed on liquids or dilute solutions of analytes, diffuse reflectance measurement in the near-infrared must deal with a composite effect of spectroscopic absorption and scattering from the analyte and the matrix in which it is found. Differences in refractive indices of the sample material, specular reflection and observance of relatively small differences are all dealt with in this technique. 

Abstract By the definition of the mole as a base unit for amount-of-substance measures within the International System of Units (SI), chemists can make chemical measurements in full compliance with established metrological principles. Since the mole requires exact knowledge of the chemical entity, which is often neither available nor of practical relevance to the purpose of the measurement, the SI units of mass or length (for volume) are unavoidable in the expression of results of many chemical measurements. Science, technology, and trade depend upon a huge and ever increasing number and variety of chemical determinations to quantify material composition and quality. Thus, international harmonization in the assessments of processes, procedures, and results is highly desirable and clearly cost effective. The authors, with relevant experience and re-... 

P. Jackson, N. J. Clayden, J. A. Barnes, T. A. Carpenter, L. D. Hall, and P. Jezzard, New analytical techniques for advanced polymer composites, in A. Kwakemaak and L. van Arkel, (Eds.), Proceedings of the 12th International European Chapter Conference of the Society for the Advancement of Material and Process Engineering, Maastricht, The Netherlands, May 28—30, 1991, Advanced Materials Cost Effectiveness, Quality Control, Health and Environment, Elsevier, Amsterdam, The Netherlands, 1991, pp. 277-288. 

There are a wide variety of parameters that induce voids in composites. Effect of these parameters on mechanical properties of composite is the subject of so many researches [10-15]. Furthermore, induced voids affect the fatigue behaviour of composite materials product [16, 17]. 

One of the more obvious examples of this interaction involves the addition of temper to a clay matrix (temper may be another clay, but is more often a nonplastic material). The effect of tempering varies a relatively pure material, such as quartz, may reduce elemental concentrations in a ceramic paste by a constant proportion (49). Addition of other kinds of temper or clay will result in a complex relationship of dilution and enrichment (14, 25, 50). Because elemental concentrations in sediments vary depending upon grain size (e.g., references 51-53), the size distributions of the added nonplastics also contribute to compositional complexity. If behavioral inferences are to be drawn, the culturally induced elemental variation arising from texture and temper differences among pottery produced from a single clay resource requires more than simple grouping and summary statistics. 

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