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 and H.Q. XIE J. Phys. IV France, 03 C4 (1993) C4-257-C4-260 DOI: 10.1051/jp4:1993439