Polymer process design basics

This introductory case study presents the key features of a conceptual process design by using the systematic methods presented in the previous chapters. The selected process is the manufacture of cyclohexanone, a key intermediate in the production of e-caprolactam and adipic acid, which are basic materials for nylon-type polymers. 

Figure 1.9 shows different kinds of flowsheets which mark the start and the end of the part of the overall design process which is covered by the case study. At the beginning, the chemical process is described by an abstract flowsheet which decomposes the process into basic steps without considering the equipment to be used (upper part of Fig. 1.9). The process consists of three steps reaction of caprolactam and water, separation of input substances which are fed back into the reaction, and compounding, which manipulates the polymer produced in the reaction step such that the end product meets the requirements. The lower part of Fig. 1.9 shows a process flowsheet which consists of chemical devices and therefore describes the chemical plant to be built - still at a fairly high level of abstraction. The process flowsheet serves as input for detail engineering, which is beyond the scope of the case study.

Following this mainly engineering view point, the first volume Polymers -Opportunities and Risks I is dedicated to the basics of the engineering of polymers (materials, processing, design, surface, use phase, recycling, depositing) - but always in view of the environmental impact. 

The principles and fundamentals presented in these chapters will be used to develop the basic understanding of the various polymer processes so that operations, analysis, design, and development can be properly treated in an engineering sense. 

In order to design and analyze polymer processes there are common steps associated with nearly every process. Following Tadmor and Gogos (1979), these basic steps are given below ... 

Shear thinning or pseudoplastic behavior is an important property that must be taken into account in the design of polymer processes. However, it is not the only property, and in Chapter 3 models that describe the viscoelastic response of polymeric fluids will be discussed. However, first we would like to solve some basic one-dimensional isothermal flow problems using the shell momentum balance and the empiricisms for viscosity described in this section. 

We do not intend in this chapter to present an extensive analysis of mass transfer concepts but, rather, to summarize the basics of mass transfer as required in the design and analysis of polymer processing operations. In this regard, we give only an extensive overview of the estimation techniques for the diffusivity, solubility, and permeability of solvents in polymers. The laws of diffusional mass transfer, as well as the relationships for convective mass transfer, remain the same as applied to any material. The books by Perry and Chilton (1973), Reid et al. (1977), and Brandmp and Immergut (1989) provide an extensive overview of experimental data and formulas for the calculation of diffusivity, solubility, and permeability of various polymer systems. 

This unified approach to polymer materials science is divided into three major sections Basic Principles, Influence of Processing on Properties, and Engineering Design Properties. 

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