Modeling of Organic Materials Processing

In an effort to reduce the empiricism involved in many polymer processing analyses and designs, this paper presents a finite element routine capable of predicting velocities, temperatures, stresses, and extents of chemical conversion in a variety of reactive polymer processes. The analysis accounts for diffusive, convective, and generation effects and also deals with transient situations.After a brief introduction on the benefits of modeling polymer processes, the equations which govern nonisothermal reactive polymer flow are outlined. Using the equations, a finite element formulation is presented which results in a new element routine capable of analyzing complex flow domains. Program features include a penalty formulation to enforce fluid incompressibility, “upwind” weighting of highly convective terms, transient analysis capabilities, and iterative procedures to accomodate material nonlinearity.The utility of the computer code is illustrated by sample analyses of representative industrial processes. These include pultrusion and reactive pressure flow which have parameters found in a number of other polymer processing operations. Material parameters as described in the literature are used and the effect of processing variables on the product internal temperatures and extents of chemical conversion are discussed.Recommendations are made for future research and model development. These include alternative solution techniques to handle more complex geometries as well as the ability to model polymer behavior past the point of gelation.