Computer-aided design and manufacture of polymers, blends and composites

The objective of this work is to develop a systematic procedure for the design of polymers, blends and composites to meet a set of target properties. The design/selection of polymeric materials to perform a desired task is a challenging problem as the possibilities are innumerable. Traditionally, a trial-and-error approach is adopted to synthesize a suitable polymeric material for a given application. This trial-and-error procedure typically involves expensive experimentation in the laboratory and is not guaranteed to culminate in the synthesis of a material that meets all the target requirements. There is, therefore, a need to develop a systematic methodology based on theory to synthesize polymer molecules that possess desired characteristics.; A computer-aided molecular design technique has been proposed to synthesize polymers with desired target properties. According to this technique, the polymer molecule will be synthesized from Universal Functional Activity Coefficient (UNIFAC) chemical groups. The group contribution theory has been utilized to correlate chemical structure with properties. The problem of synthesizing the desired molecule is formulated as a mixed integer nonlinear program. The program will have the potential of designing addition and condensation polymers and their blends. The molecules may be aliphatic or aromatic in nature. A global optimization technique is introduced to solve synthesis problems of reasonable dimensionality will also be discussed. Case studies are solved to illustrate the efficacy of the synthesis procedure.; Textile composites are special polymeric materials that possess superior specific properties in comparison to simple plastics or metals. These composite materials are composed of a polymer matrix reinforced with a textile fabric. While the fabric gives excellent strength and elastic properties, the matrix gives excellent shear properties and resistance to corrosion. The elastic behavior of textile composites depends on a number of factors including: fiber and matrix properties, fabric architecture and relative and total fiber volume fractions. The optimum design of a textile composite is, therefore, a highly combinatorial problem. The framework of mathematical optimization has been used in this work to solve the problem of predicting the optimum matrix properties, fabric architecture and fiber volume fractions to achieve a set of target elastic properties. The design procedure uses the Stiffness Averaging Technique for the prediction of composite elastic properties. Once the optimum matrix properties are identified, the proposed molecular design methodology is employed to identify the most appropriate polymer to be used as the matrix.; Some aspects of manufacture of polymeric materials has also been studied. Some key issues considered are the fiber-matrix compatibility, polymer processing and optimal lay-up of reinforcements. Compression molded polymer composite products were manufactured and tested for properties. In particular, the results for a polypropylene reinforced polyethylene composite is presented.