Modeling and study of properties distribution in graded polymer materials

Abstract

Functionally graded materials (FGMs), the composition and properties of which continuously vary in cross-section, are of great interest for various applications today. This paper proposes an original method for assessing the composition and properties distribution in FGMs. Graded polymer materials were obtained based on poorly compatible epoxy oligomers (epoxy resin NPEL-128 and triglycidyl phosphate (TGP)). A mathematical description of the separation process of components showing incompatibility in the middle range of concentrations was provided. At the initial time after blending the mixture of two oligomers is an emulsion. The composition gradient is formed as a result of spontaneous settling due to the difference in the densities of the phases. As a result, after curing, a polymer material with graded composition and properties is formed. Elemental analysis showed that the triglycidyl phosphate gradually increases from the top to the bottom of the sample in the forming polymer material. The through-thickness distributions of microhardness and glass temperature were determined. The original semi-empirical method was used to determine the modulus of elasticity and the coefficient of thermal expansion distribution. It was shown that glass temperature, microhardness and modulus of elasticity increase from the top to the bottom of the samples. On the contrary, the thermal expansion coefficient gradually decreases. Such properties variations over the cross section are explained by the graded composition.The obtained data prove that during the separation of the NPEL-128/TGP emulsion, a polymer material with a graded composition and properties is formed.

Keywords

• Functionally graded material
• Triglycidyl phosphate
• Phase diagram
• Microhardness
• Glass temperature
• Modulus of elasticity