Single wall carbon nanotubes (SWCNTs) often aggregate into bundles of hundreds of weakly interacting tubes. Their cross-polymerization opens new possibilities for the creation of new super-hard materials. New mechanical and electronic properties are expected from these condensed structures, as well as novel potential applications. Previous theoretical results presented geometric modifications involving changes in the radial section of the compressed tubes as the explanation to the experimental measurements of structural changes during tube compression. We report here results from molecular dynamics simulations of the SWCNTs polymerization for small diameter arm chair tubes under compression. Hydrostatic and piston-type compression of SWCNTs have been simulated for different temperatures and rates of compression. Our results indicate that large diameter tubes (10, 10) are unlike to polymerize while small diameter ones (around 5 angstrom) polymerize even at room temperature. Other interesting results are the observation of the appearance of spontaneous scroll-like structures and also the so-called tubulane motifis, which were predicted in the literature more than a decade ago. (C) 2007 Wiley Periodicals, Inc.281017241734