Cell Size Effect on the Mechanical and Viscoelastic Behavior of Microcellular Plastics

In the paper, the mechanical properties and its viscoelastic behavior of microcellular plastics ware investigated with particular emphasis on the role of cell size. A polyethylene terephtalate resin (CPET) modified with a polyolefin nucleating agent was selected as the specimens. In order to investigate the role of cell size, microcellular CPET samples were produced having constant cell density of 109 cells per cubic centimeter, and a varying cell size in the range of 3 to 10μm.The storage modulus time-temperature dependence of microcellular plastics was measured by using a viscoelastic analyzer and the tensile strength was investigated by use of a hydraulic tensile test machnine. It was found that compared with the original polymer, the storage modulus of microcellular polymers appears to relieve at a slower rate at elevated temperatures. The tensile strength of microcellular CPET with cell size of 3.5μm equals or more that of the original material.