Processing method

Mixing The general methods for incorporating compounding ingredients into dry natural rubber involve the use of either a two roll mill or an internal mixer (e.g. Banbury mixer). Both in the open mill and in the internal mixer, a definite time, temperature, and order of addition of ingredients should be followed for each batch. [59] 

Calendering The rubber calender is essentially a device for forming rubber sheeting of continuous length and uniform thickness. It is also used extensively for frictioning or skim coating of fabric/cord/wires with rubber for making 

Extrusion Extruders are machines which force rubber through a nozzle or die to a profiled strip of material. Extruders are of two basic types screw extruders and ram extruders. A screw extruder comprises a feed hopper, a feed screw operating within a barrel, and a die. 

In the ram extruder, a ram pushes a quantity of warm compound placed into the cylinder. The operation of this type of machine is intermittent, and the operating costs are higher. 

Transfer moulding In transfer moulding the uncured rubber compound is transferred from the loading chamber (pot) of the transfer mould into the actual mould cavity. This technique is suitable for moulding products of a complicated shape, and for anchoring delicate inserts in mouldings. 

The bacteriocin nisin has been added to canned foods to reduce the severity of heat processing due to its ability to prevent the outgrowth of Clostridium botulinum spores (Daeschel, 1989). Most sterilised products, however, do not contain any antimicrobial preservative. 

The pouches used for sous-vide products must be impermeable to water and oxygen. They must also be heat-tolerant and puncture-proof. Shrink pouches are appropriate for products such as meat, as they form a skin around the food. Non-shrink pouches are used for fish and other delicate items. 

Three factors are critical for safe sous-vide products oxygen level in the pouch, heat-treatment conditions and refrigeration temperature (Leadbetter, 1989). 

About 2% oxygen remains in the pouch even with vacuum packaging. This will be utilised by any aerobic microorganisms present until it is exhausted. After it is exhausted, only facultative anaerobes such as Salmonella, Yersinia, Staphylococcus and Listeria spp. and strict anaerobes such as Clostridium botulinum and Clostridium perfringens can grow. 

Heat treatment is used to kill non-sporing bacteria and most yeasts and moulds. Although most or all spore-forming bacteria will be killed, spores will remain, as they are much more heat-resistant. Spores of the pathogenic Clostridium botulinum and Clostridium perfringens will survive. C. perfringens is effectively controlled by refrigeration, but C. botulinum must be controlled as it causes the potentially fatal disease, botulism, if sufficient toxin is allowed to develop in the product and is then consumed (Table 6.1). Bacillus spp. are probably not a serious threat as they are aerobic (Leadbetter, 1989). 

Additives may be introduced into the polymer either before it is processed to give the final product or during the processing. Although it is important to ensure that the components are adequately mixed, there is not space here to deal with the details of the mixing processes. The processing methods are therefore described as if the feed material were homogeneous. 

The principal processing methods are (i) injection moulding, (ii) extrusion, (iii) blow moulding, (iv) calendering, (v) thermoforming and (vi) reaction moulding. These are now considered in turn. 

Injection moulding allows the automated mass production of articles that may have complex shapes and whose properties can be varied by choosing different materials and the appropriate processing conditions. The basic principle of the method is shown in fig. 1.8(a). Polymer contained in a hopper is fed into a cylinder where it is pushed by a ram or plunger through a heated region, in which it melts, into a mould. The filled mould is allowed to cool and the solidified product is ejected. The ram is then drawn back and the process is repeated. This simple process suffers from a number of disadvantages and modern injection moulders are always of the screw-injection type illustrated in fig. 1.8(b). 

During the injection part of the cycle, the screw is used as a plunger to drive the polymer forwards into the mould. When the mould is full and the 

8 (a) A schematic outline of a basic ram injection-moulding machine, (b) A singlescrew injection-moulding machine, showing the injection unit, ((a) 

2) Doping with fimcdonal dopants the properties of the ICPs, such as solubility in organic solvent [86] or water [87-91], can be modified by doping with appropriate dopant Camphorsulfonic acid is one of such dopants. CSA-doped PANI can be dissolved in m-cresol. A number of researchers [30, 60, 62, 64] blended 

PANI-CSA/m-cresol solution with PMMA/m-cresol solution to prepare PANI-CSA/PMMA coatings to investigate the corrosion protection property. In some cases, the dopant can also be polymer matrix. Oliveira et al. [92] prepared poly (methyl methacrylate-co-acrylic acid) (PMMA-co-AA)-doped PAN I by using the template-guided method. The doped PANI (PANI-PMMA-co-AA) was soluble in ethyl acetate, and the solution was used for dip coating plates of aluminum alloy. 

Molecular materials are more commonly prepared and studied as single crystals. In such morphology, they cannot be easily applied to device 

In solution-based techniques (wet techniques), such as dip coating 

Growth of molecular inorganic conductors and superconductors as films or nanowires is mainly conducted by electrodeposition due to the physico-chemical properties of the precursors and the necessary electrochemical activation to produce the conductive phase. 

Electrocrystallisation is the usual method appHed to grow single crystals of molecule-based conductive materials. Confined electrocrystallisa- 

The fabrication of organic transistors requires both patterned structures and thin continuous layers. Films can be produced by combining printing 

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On a land site where space and weight are not normally constraints, advantage can be taken of tank type separation equipment such as wash tanks and settling tanks, and batch processing methods. Such equipment is generally cheaper to maintain than continuous throughput vessels, though a combination of both may be required. 

AUGUR software is used to obtain two- and three-dimensional images of defects using various coherent data processing methods, determine the sizes of defects in different sections, execute service and report preparation operations. 

Shear Horizontal (SH) waves generated by Electromagnetic Acoustic Transducer (EMAT) have been used for sizing fatigue cracks and machined notches in steels by Time-of-Flight Diffraction (TOED) method. The used EMATs have been Phased Array-Probes and have been operated by State-of-the-art PC based phased array systems. Test and system parameters have been optimised to maximise defect detection and signal processing methods have been applied to improve accuracy in the transit time measurements. 

To restore resolution, we proposed a signal processing method based on Papoulis deconvolution. We implemented this algorithm and tried to operate an improvement from an aluminum rod smaller than the wavelength. 

Williams R 1990 Modern GaAs Processing Methods (Norwood Artech House)... 

Nomenclature is the compilation of descriptions of things and technical terms in a special field of knowledge, the vocabulary ofa technical language. In the history of chemistry, a systematic nomenclature became significant only rather late. In the early times of alchemy, the properties of the substance or its appearance played a major role in giving a compound a name. Libavius was the first person who tried to fix some kind of nomenclature in Alckeinia in 1,597. In essence, he gave names to chemical equipment and processes (methods, names that are often still valid in our times. 

If the task is multivariate calibration, for example, the proper choice of a pre-processing method will essentially aflFect the quality of the resultant model. For more details about the use of these techniques together with PCA and PLS, readers are advised to consider the fundamental monograph by Erikson et al [8]. 

Prior to PCA the data are often pre-processed to convert them into a form most suitable for the application of PCA. Commonly used pre-processing methods for PCA arc scaling and mcaii-ccntcring of the data, which arc described in Section 4.3. 

LPC Processes. Process development for LPC production dates from the United Kingdom and Hungary from 1920—1940 (89,90). Table 9 presents some of the processing methods that are used or under development in the 1990s. 

History. Methods for the fractionation of plasma were developed as a contribution to the U.S. war effort in the 1940s (2). Following pubHcation of a seminal treatise on the physical chemistry of proteins (3), a research group was estabUshed which was subsequendy commissioned to develop a blood volume expander for the treatment of military casualties. Process methods were developed for the preparation of a stable, physiologically acceptable solution of alburnin [103218-45-7] the principal osmotic protein in blood. Eady preparations, derived from equine and bovine plasma, caused allergic reactions when tested in humans and were replaced by products obtained from human plasma (4). Process studies were stiU being carried out in the pilot-plant laboratory at Harvard in December 1941 when the small supply of experimental product was mshed to Hawaii to treat casualties at the U.S. naval base at Pead Harbor. On January 5, 1942 the decision was made to embark on large-scale manufacture at a number of U.S. pharmaceutical plants (4,5). 

Fig. 7. Approximate viscosity values for forming and processing methods (Pa-s x 10 = P).

Glass-ceramic articles can be fabricated by means of either bulk or powder processing methods. Both methods begin with melting a glass of the desired composition. 

Material Reference Sensitivity, J/cm Resolution, lines / mm Wavelength, nm Processing method... 

However, in the case of mini- and microemulsions, processing methods reduce the size of the monomer droplets close to the size of the micelle, leading to significant particle nucleation in the monomer droplets (17). Intense agitation, cosurfactant, and dilution are used to reduce monomer droplet size. Additives like cetyl alcohol are used to retard the diffusion of monomer from the droplets to the micelles, in order to further promote monomer droplet nucleation (18). The benefits of miniemulsions include faster reaction rates (19), improved shear stabiHty, and the control of particle size distributions to produce high soHds latices (20). 

J. P. Homak and L. M. Fletcher, in E. R. Dougherty, ed.. Digital Image Processing Methods, Marcel Dekker, New York, 1994. 

The primary difference in shale oils produced by different processing methods is in boiling point distribution. Rate of heating, as well as temperature level and duration of product exposure to high temperature, affect product type and yield (28). Gas combustion processes tend to yield slightly heavier hquid products because of combustion of the lighter, ie, naphtha, fractions. 

Processing Methods. LLDPE is easHy processed by most conventional techniques due to its low melting point and high chemical stabHity the principal techniques have been described (60—65). 

Synthesis. Exploratory research has produced a wide variety of odorants based on natural stmctures, chemicals analogous to naturals, and synthetic materials derived from available raw materials and economical processing. As in most areas of the chemical industry, the search for new and useful substances is made difficult by the many materials that have been patented and successfully commercialized (4). In the search for new aroma chemicals, many new materials are prepared for screening each year. Chemists who perform this work are involved in a creative exercise that takes its direction from the commercial sector in terms of desirable odor types and specific performance needs. Because of economic limitations, considerations of raw material costs and available processing methods may play a role eady in the exploratory work. 

Phosgene addition is continued until all the phenoHc groups are converted to carbonate functionahties. Some hydrolysis of phosgene to sodium carbonate occurs incidentally. When the reaction is complete, the methylene chloride solution of polymer is washed first with acid to remove residual base and amine, then with water. To complete the process, the aqueous sodium chloride stream can be reclaimed in a chlor-alkah plant, ultimately regenerating phosgene. Many variations of this polycarbonate process have been patented, including use of many different types of catalysts, continuous or semicontinuous processes, methods which rely on formation of bischloroformate oligomers followed by polycondensation, etc. 

Depending on the requirements of the chemical procedure, the processing method may be varied with different mechanical arrangements to remove the by-product, water, in order to drive the esterification reaction toward completion. 

The processing methods for siHcone mbber are similar to those used in the natural mbber industry (59,369—371). Polymer gum stock and fillers are compounded in a dough or Banbury-type mixer. Catalysts are added and additional compounding is completed on water-cooled roU mills. For small batches, the entire process can be carried out on a two-roU mill. Heat-cured siHcone mbber is commercially available as gum stock, reinforced gum, partially filled gum, uncatalyzed compounds, dispersions, and catalyzed compounds. The latter is ready for use without additional processing. Before being used, sihcone mbber is often freshened, ie, the compound is freshly worked on a mbber mill until it is a smooth continuous sheet. The freshening process eliminates the stmcturing problems associated with polymer—filler interactions. 

Production of net-shape siUca (qv) components serves as an example of sol—gel processing methods. A siUca gel may be formed by network growth from an array of discrete coUoidal particles (method 1) or by formation of an intercoimected three-dimensional network by the simultaneous hydrolysis and polycondensation of a chemical precursor (methods 2 and 3). When the pore Hquid is removed as a gas phase from the intercoimected soHd gel network under supercritical conditions (critical-point drying, method 2), the soHd network does not coUapse and a low density aerogel is produced. Aerogels can have pore volumes as large as 98% and densities as low as 80 kg/m (12,19). 

The seven processing steps shown schematically in Figure 1 are involved to various degrees in making sol—gel-derived siUca monoliths by methods 1, 2, and 3. The emphasis herein is primarily on net-shape sol—gel-derived siUca monoliths made by the alkoxide process (method 3) prepared under ambient pressures. 

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