Diffused Reflection Performance of Microcellular Foamed Polyethylene Naphthalate

Abstract

Due to the increasing demand for high-performance diffuse reflectors in applications including LCD displays and lighting, many studies on the manufacturing of high-performance reflectors have been conducted. Microcellular foamed plastics are characterized as having a structure with a cell size of 10 µm or less along with a cell density of at least 10⁹ cells/cm³. Since the structural characteristics of these materials were determined to result in diffused reflection, the use of polymers as diffuse reflectors has been studied. In this study, a diffuse reflector specimen was manufactured by applying a microcellular foaming process to polyethylene naphthalate (PEN). The optimum foaming conditions of PEN were determined through preliminary experiments using the Batch process and the specimen was manufactured using supercritical CO₂. Additionally, to improve the low productivity, which is one of the disadvantages of the Batch process, additional specimens were manufactured while varying the saturation conditions. Through observation of the cross-sections of the specimens, the cell morphology depending on the process conditions was confirmed and then, the diffusion reflectivity was measured.

Keywords:

• Batch process
• Cell morphology
• Diffusion reflectivity
• Microcellular foaming process
• Polyethylene naphthalate (PEN)