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The formation of crystal cross-linked network in sequential biaxial stretching of poly(ethylene terephthalate): The essential role of MD pre-stretch.
- Source :
-
Polymer Testing . Apr2021, Vol. 96, pN.PAG-N.PAG. 1p. - Publication Year :
- 2021
-
Abstract
- Combining a homemade uniaxial stretching device and the simultaneous in-situ synchrotron radiation WAXS measurement, the structural evolution during transverse direction (TD) stretching of machine direction (MD) pre-stretched Poly(ethylene terephthalate) (PET) film has been investigated. Current work reveals that increasing the MD pre-stretch before the occurrence of stretch induced crystallization (SIC) can enhance the crystallization and orientation in TD stretching. The concept of parallel chains structures (PCS) cross-linked network is proposed to interpret the rubber-like mechanical behavior. An appropriate stretch ratio window in stretching above the glass transition temperature (T g) is existed, where the PCS cross-linked network before crystallization can be induced by stretching above T g. With the help of the PCS cross-linked network, the chain orientation is retained more effectively under stretching, promoting the formation of subsequent crystallization and crystal cross-linking network. The strain hardening in different pre-stretched samples occurs accompanied by the same crystallinity and various chains orientation. This demonstrates that the strain hardening is determined by the crystal cross-linked network rather than the orientation. Current work supplies a guidance for getting the improved film products of PET with enhanced comprehensive mechanical properties, process stability and higher chain orientation. • The structural evolution in subsequent stretching of pre-stretched Poly(ethylene terephthalate) (PET) film is investigated by the in-situ synchrotron radiation WAXS measurement. • The origin of the novel rubber-like mechanical behavior under the complicated stretching field is better understood by the combination of the in-situ chains orientation, crystallization behavior and mechanical behavior. • The concept of parallel chains structures (PCS) cross-linked network is proposed to interpret the rubber-like mechanical behavior. • The onset of strain hardening corresponds to the formation of the crystal cross-linked network. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01429418
- Volume :
- 96
- Database :
- Academic Search Index
- Journal :
- Polymer Testing
- Publication Type :
- Academic Journal
- Accession number :
- 149369823
- Full Text :
- https://doi.org/10.1016/j.polymertesting.2021.107143