Step function terms Links

We noted above that the presence of monomer with a functionality greater than 2 results in branched polymer chains. This in turn produces a three-dimensional network of polymer under certain circumstances. The solubility and mechanical behavior of such materials depend critically on whether the extent of polymerization is above or below the threshold for the formation of this network. The threshold is described as the gel point, since the reaction mixture sets up or gels at this point. We have previously introduced the term thermosetting to describe these cross-linked polymeric materials. Because their mechanical properties are largely unaffected by temperature variations-in contrast to thermoplastic materials which become more fluid on heating-step-growth polymers that exceed the gel point are widely used as engineering materials. 

Scatter search has been implemented in software called OPTQUEST (see www.opttek.com). OPTQUEST is available as a callable library written in C, which can be invoked from any C program, or as a dynamic linked library (DLL), which can be called from a variety of languages including C, Visual Basic, and Java. The callable library consists of a set of functions that (1) input the problem size and data, (2) set options and tolerances, (3) perform steps 1 through 3 to create an initial reference set, (4) retrieve a trial solution from OPTQUEST to be input to the improvement method, and (5) input the solution resulting from the improvement method back into OPTQUEST, which uses it as the input to step 7 of the scatter search protocol. The improvement method is provided by the user. We use the term improvement loosely here because the user can simply provide an evaluation of the objective and constraint functions. 

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