Foam final product properties

In summary of foam-spray drying, all available literature results confirm a strong effect of feed foaming on final product properties of porous and skin-forming materials, for example, an increase of Sauter mean diameter and porosity of the products decrease of bulk, tap density, and apparent density and effect on particle morphology. Foam-spray drying enhances retention of highly volatile substances and... 

Although, since that time, very few studies on foam spray drying have been reported, this technology has more recently attracted attention because of the possibilities of processing hard-to-dry food materials and to control the final product properties such as bulk density, porosity, solubility, and wettability. 

A systematic analysis of the foam spray drying process, including investigations of spray hydrodynamics (particle size distribution, particle velocity, centricity), heat and mass transfer between the phases, drying kinetics and the effects of feed foaming on final product properties, was carried out by Zbicinski and Rabaeva (2010) and Rabaeva (2012). 

AD available studies revealed a strong effect of feed foaming on the final product properties. 

Changes in the final product properties of whole-milk foamed with nitrogen, as presented by Hanrahan et al. (1962), are listed in Tab. 6.2. An analysis of the data in Tab. 6.2 shows a decrease in the bulk density of the product, increases in the free fat content and dispersibility, and also an increase in the average individual particle diameter at a higher nitrogen injection rate. 

Foam drying techniques enable the processing of difficult-to-dry materials (e.g., fruit pulps, juices and dairy products) at low temperatures and with short drying times. As a consequence, the thermal degradation of dry products can be reduced when compared to the convective drying of non-foamed materials, whilst the desired final product properties can be obtained. 

Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. The performance properties of polyurethane can be widely modified by selecting appropriate raw materials, catalysts and auxiliary compounds, by employing various production methods and/or by employing various methods for further processing and/or for shaping the final products. Therefore, polyurethanes have wide applications such as elastomer, coating, adhesive, foam, and leather. 

This book describes the chemistry, manufacture and use of the wide range of flexible polyurethane foams, from low-density open-cell upholstery foams to microcellular and reaction- injection-molded and reinforeed-reaction-injection-molded materials. The related effects of varying the raw-material chemistry and the production process and machinery on the properties and service performance of the final product are indicated. 

A second function of the catalyst is to drive the polymer-forming reactions as near to completion as possible and effect optimum cure of the foam. This is necessary to develop optimum properties such as maximum strength and minimum compression set in the final product. The catalysts most commonly used are tertiary amines as well as organometal and other metal compounds. 

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