Inspired by Professor Li Liangbin and Dr. Meng Lingfufu, the master Zhang Wenwen in our laboratory studied the The effect of water absorption on stretch-induced crystallization of poly(ethylene terephthalate) by using the self-made pull device and the Shanghai synchrotron radiation source. The results were published in the journal Polyme (2019, 162: 91-99).
Different from extensive investigations of flow-induced crystallization of polyethylene and isotactic polypropylene at the temperature around melting point (Tm), SIC of PET has been mostly investigated around Tg, where chain mobility rather than nucleation barrier is the rate limited factor for crystallization according to classic nucleation-growth theory. Aiming to investigate the roles of chain mobility and stretch in SIC, the structural evolution of PET samples absorbing different contents of water from 0 to 1.15 wt % were investigated with in-situ synchrotron radiation WAXS during the uniaxial stretch at 90 °C (slightly above Tg) in this work. Combining the mechanical behavior and in-situ 2D WAXS data, the results show that activation of chain mobility through destroying the “frozen orders” is always a necessary precondition for SIC even with water as plasticizer. Absorption of water does not enhance but suppresses SIC though it does promote the chain mobility.
The work is supported by the National Natural Science Foundation of China (51890872, 51633009) the National Key Research and Development Program of China (2018YFB0704200). The authors thank Guofeng Plastic Industry Co. Ltd for providing the precursor films of this experiment. The authors also thank Dr. Yanwei Ding (University of Science and Technology of China) for his support in DSC and TGA measurement; thank the team in Synchrotron Radiation Facility of Shanghai for the assistance during the WAXS measurement.
Related links:https://www.sciencedirect.com/science/article/pii/S0032386118311431
