Structural transition of polyethylene oxide networks studied by positron annihilation B. WANG, Z.L. PENG, Y.Q. DAI, S.Q. LI, S.J. WANG, H. LIU et H.Q. XIE J. Phys. IV France, 03 C4 (1993) C4-257-C4-260 DOI: 10.1051/jp4:1993439