Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide
Jingjing Li a, Chongshan Yin a, Yawei Zhou a, Gang Li b, Jen-taut Yeh b and Chunqing Hea
aKey Laboratory of Nuclear Solid State Physics, Hubei Province, School of Physics and Technology, Wuhan University, Wuhan 430072, China
bHubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education, Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, Wuhan, China
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Free volume variations of Nylon12/Polyvinyl alcohol (Nylon12/PVA) blends treated in supercritical carbon dioxide (ScCO2) were investigated using positron annihilation lifetime spectroscopy. It is found that o-Ps lifetime τ3 and the corresponding intensity I3 in Nylon12/PVA decrease with increase of the PVA content. Being treated in ScCO2 at 50°C and 20 MPa for 1 h, the free volume holes in Nylon12/PVA blends expand to different extents depending on the weight ratio of PVA. After releasing of CO2, the free volume size decreases as a function of the elapsed time due to the molecular relaxation, and the relaxation time constant depends on the content of PVA in the blends.

DOI: 10.12693/APhysPolA.132.1552
topics: Nylon12/PVA, ScCO2, positron annihilation, free volume, relaxation