Browsing by Author "Jones, William Crawford"

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    The effects of fillers on the mechanical properties of polyester resin and a constrained optimization of filler content
    Jones, William Crawford (Virginia Polytechnic Institute and State University, 1970)
    A study was made to determine the effects of fillers on the mechanical properties of a flexible polyester resin. Also, a method was demonstrated for a constrained optimization of the volumetric cost of the filled polyester. The fillers investigated included clay, marble, nut shell flour, and glass beads and microspheres. Mechanical property data were generated for different filler concentrations and particle sizes. The properties tested were density, tensile strength, ultimate elongation, secant modulus, and flexural strength. Testing was performed according to standard methods using an Instron Universal Testing Machine with strain gage. Contrary to the results of previous investigators, rigid particulate fillers (e.g., clay, marble, and nut shell flour, excluding glass beads and microspheres) significantly increased the tensile strength of the resin. Increases in flexural strength were observed for certain fillers. Both tensile and flexural strength improvements were greater for smaller particles than for larger ones. The fillers increased the modulus and decreased the ultimate elongation of the resin. The method of optimization included an experimental design to generate data and a polynomial regression analysis to determine the mechanical property constraint functions. The constraints were well approximated by linear functions, and linear programming was used to find an optimum. The linear functions could also be used to give a reasonable approximation of the mechanical property constraints outside the experimental region.