Nascent structures during the polymerization of ethylene

Evaluation of the Initial Stages of Gas‐Phase Ethylene Polymerizations with a SiO2‐Supported Ziegler–Natta Catalyst

“…[4,5] The nascent phase of these polymerizations has been widely studied, but more from the point of view of exploring the relation between the crystallization, formation of the polymer chains and the impact of monomer transport upon the polymer morphology. [6][7][8][9][10][11][12][13] In spite of the importance of studies regarding the development of polymer particle morphology, the real impact of the reaction conditions on the morphogenesis of the polymer particles has not been completely explained. The morphology of the final polymer particle depends on the mechanical and structural properties of both the catalyst support and the polymer formed in the critical very early stage of the polymerization.…”

Morphology and melting behavior of nascent ultra-high molecular weight polyethylene

“…Sample B was polymerbeen drawn. 21,23,28 Although different catalyst/ ized in hexane using Ziegler-Natta catalyst and synthesis conditions clearly play a role, there is diethylaluminum chloride activator at 60ЊC using no consensus on the origin of the high value for H 2 to regulate molecular weight. Intrinsic viscosthe peak melting point commonly seen in the naity was determined by ASTM D 4020-92.…”

“…Samples scent state of polyethylene. 20,21,27 -34 Interpretafor compression molding were formed in a Buehler tions which invoke chain-extended and/or fibrilmount press at 195ЊC (5000 psi, 5 min), and relar crystals, 20,21,27,28 strained noncrystalline tie heated at 195ЊC (low pressure, 10 min) to minipoints, 31,32 instrumental effects, 33 or small crysmize residual orientation. Additional samples tals which reorganize on heating 34 have been inwere prepared by annealing flake and moldings voked to describe aspects of the thermal behavior.…”

Solid-state 1H-NMR relaxation behavior for ultra-high-molecular-weight polyethylene reactor powders with different morphologies

“…The assignment of the fibrillar structure of the Hostalen powder is also of interest. This structure is formed by internal expansion stress during polymerization, 24,25 Because the intermediate component also exhibits restricted molecular motion, the characteristics of this component and those of the fibrillar structure are similar. However, this assignment requires further supporting data, such as the morphological changes that occur while heating the reactor powder.…”