Structural Characterization of PET Film by X-ray Scattering by Near Melting Point Stretching
Year: 2018
Type: article
Abstract: Biaxial oriented Poly (ethylene terephthalate) film is excellent in heat resistance and transparency, which is utilized in industrial and packaging application. Heat resistance or other properties are achieved by biaxial orientation method, which is characterized in machine-directional and transverse-directional stretching. The amount of heat, temperature profile, or draw ratio in stretching process improves the film properties, and the stretching temperature is generally set on near glass transition point. In this research, a trial to heighten the biaxial stretching temperature to near melting point was made. PET loses the thickness homogeniety during biaxial stretching at near melting point, because tensile stress decreases, which are experimentally apparent. However, this study overcame it by undergoing heat crystallization of uniaxial stretched sheet. The obtained film exhibited characteristic properties compared to usual PET film. The film had high crystallinity, low MD orientation, and exhibited excellent thermal dimensional stability in MD. The amorphous orientation was suggested to be relaxed. Furthermore, in-situ characterization of biaxial stretching process revealed that crystallinity was retained during stretching at near melting point, which was not observed during usual stretching. In usual stretching, crystallinity was temporary decreased. Taken together, the stretching at near melting point exhibited notable structural formation and film properties. This study achieved some possibility in developing new biaxial stretching process of PET for the higher functioning film.
Source: Seikei-Kakou
Institution: Toyobo (Japan)
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W3081007604