화학적으로 재생된 폴리에틸렌테레프탈레이트의 물성향상 연구

Abstract

The simple pre-crystallization process of the chemically recycled and virgin poly(ethylene terephthalate) (PET) was placed in boiling water for an hour. To enhance the physical properties, untreated chemically recycled and virgin PET chips were treated by pre-crystallization process. The nuclear magnetic resonance (1H NMR) was used to confirm the structure of the dimethyl isophthalate (DMIP) and diethylene glycol (DEG). The weight average molecular weight, Mw; the number average molecular weight, Mn and the molecular weight distribution Mw/Mn were measured. The mechanical, thermal properties and crystallinity of treated PET and untreated PET were investigated. Tensile tests revealed that the mechanical properties of the PET chips were increased by pre-crystallization process. The melt flow index and crystallinity were also investigated. The pre-crystallization process improved effectively the crystallization rate of the chemically recycled PET because of the nucleating effect of residual metal catalyst or oligomers. Blends of chemically recycled and virgin poly(ethylene terephthalate) (PET) were prepared using a melt-blending process. To enhance the physical properties, virgin PET chips were added to the chemically recycled PET in ratios of 20, 40, and 70 wt%. The mechanical and thermal properties, thermal shrinkage, and crystallinity of the blends were investigated. The thermal shrinkage of the blends decreased with increasing chemically recycled PET content. Tensile tests revealed that the tensile strength and elongation at break of the chemically recycled/virgin PET blends were increased by the addition of virgin PET. The melt flow index and melt density of chemically recycled PET were also investigated. The thermal stability of the blends increased as the virgin PET content increased. The color index of chemically recycled/virgin PET blends showed yellowing by chemically recycled PET.