Free-volume hole distributions of polymers by positron annihilation lifetime spectroscopy G.H. DAI, Q. DENG, J. LIU, H. SHI, C.M. HUANG and Y.C. JEAN J. Phys. IV France, 03 C4 (1993) C4-233-C4-239 DOI: 10.1051/jp4:1993435