The research of preparation of high tenacity polyester and its characterization have been studied by supermolecular modification using heating, stretching and quenching. The partially oriented and crystallined polyester fibers were heating with various temperatures, stretching with various draw ratios, and quenching in order to make the difference crystallinity and orientations. From some testing, result it can be concluded that the combination of heating, stretching, quenching with the repeating processes at higher temperature will give the highest crystallinity and orientation. The higher the crystalling of polyester, tenacity and dimension stability tend to increase, however the elongation tend to decrease. Keywords: High tenacity polyester fiber, Supermolecular modification. Zubaidi; Balai Besar Penelitian dan Pengembangan Industri Tekstil-DEPERIN
