Foam processing principles

Gendron R (2005) Thermoplastic foam processing. Principles and development. CRC Press, Boca Raton... 

Crawford RJ (1996) Rotational moulding of plastics, 2nd edn. The Queen s University of Belfast, UK http //www.research-studies-press.co.uk/crawf Fendler JH (1998) Nanoparticles and nanostructured films. Wiley, New York Gendron R (2005) Thermoplastic foam processing - principles and development. CRC, Boca Raton... 

Eoamable compositions in which the pressure within the cells is increased relative to that of the surroundings have generally been called expandable formulations. Both chemical and physical processes are used to stabilize plastic foams from expandable formulations. There is no single name for the group of cellular plastics produced by the decompression processes. The various operations used to make cellular plastics by this principle are extmsion, injection mol ding, and compression molding. Either physical or chemical methods may be used to stabilize products of the decompression process. 

This brief review has attempted to discuss some of the important phenomena in which surfactant mixtures can be involved. Mechanistic aspects of surfactant interactions and some mathematical models to describe the processes have been outlined. The application of these principles to practical problems has been considered. For example, enhancement of solubilization or surface tension depression using mixtures has been discussed. However, in many cases, the various processes in which surfactants interact generally cannot be considered by themselves, because they occur simultaneously. The surfactant technologist can use this to advantage to accomplish certain objectives. For example, the enhancement of mixed micelle formation can lead to a reduced tendency for surfactant precipitation, reduced adsorption, and a reduced tendency for coacervate formation. The solution to a particular practical problem involving surfactants is rarely obvious because often the surfactants are involved in multiple steps in a process and optimization of a number of simultaneous properties may be involved. An example of this is detergency, where adsorption, solubilization, foaming, emulsion formation, and other phenomena are all important. In enhanced oil recovery. 

This book provides an introduction to the colloid and interface science of three of the most common types of colloidal dispersion emulsions, foams, and suspensions. The initial emphasis covers basic concepts important to the understanding of most kinds of colloidal dispersions, not just emulsions, foams, and suspensions, and is aimed at providing the necessary framework for understanding the applications. The treatment is integrated for each major physical property class the principles of colloid and interface science common to each dispersion type are presented first, followed as needed by separate treatments of features unique to emulsions, foams, or suspensions. The second half of the book provides examples of the applications of colloid science, again in the context of emulsions, foams, and suspensions, and includes attention to practical processes and problems in various industrial settings. 

Starch is suitable in principle for processing as a thermoplastic. Water retained in the starch can function as a plasticiser. Starch has also been used as a raw material for producing foams. 

Since it is the properties of foams that determine their application in technological processes, it is reasonable to group foams and to establish the general principles of optimisation of foam properties, such as the conditions of foam formation, composition of the initial foaming solution, physicochemical parameters of the foam produced, etc. 

The physicochemical features of the processes of formation, stabilisation and solidification of foams are best studied for a polymer foam from urea-formaldehyde resins. That is why the urea polymer foams are used here below to exemplify the principles of optimisation of the technology for production of polymer foam materials. 

In principle, both the one-shot process and semi-prepolymer processes have been used for rigid-urethane-foam manufacturing. However, the monomeric TDI-based one-shot process was used only in the initial stage of the rigid-urethane-foam industry because of the toxicity problems of TDI and difficulties in controlling reactivity due to the high NCO percent. For these reasons TDI-prepolymers, blends of TDI prepolymers and polymeric isocyanates, and 100% polymeric isocyanate are most widely used. 

In Japan very large quantities of metal-siding board (consisting of metal sheet/phenolic foam/flexible-facing material) are manufactured as exterior materials in budding construction. This material is also manufactured using the same principle as that in the laminate process. 

Basic Principles Polymeric Foams—Preparation, Processes and Properties, Technomic Publishing Co., Lancaster, PA... 

Foam separation process involves the selective adsorption of the surface-active pollutants at the gas-liquid interfaces of fine air bubbles in a foam separation column. The surface-active pollutants, which are adsorbed on the surfaces of the rising bubbles, can be carried upward to the top of the foam separation column and thus removed from the aqueous system as condensed foam. Foam separation can be used for both waste treatment and water purification. This section presents the data on the feasibility of removing various organics and inorganics by the foam separation processes. A general survey of foam separation process and its fundamental principles are also presented. 

The basic principle for solid/liquid and solute/liquid separation by the adsorptive bubble separation processes has been introduced previously. This section further presents fundamental principles on foam phenomena and foam separation cell s operation. 

---