Characterization of Polyethylene Nascent Powders Synthesized with TpTiCl2(OR) Catalysts |
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Authors: | Emilio Casas Arquímedes Karam Antonio Díaz-Barrios Carmen Albano Yanixia Sánchez Bernardo Méndez |
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Institution: | 1. Laboratorio de Polímeros, Centro de Química, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 21827, Caracas 1020-A, Venezuela;2. Facultad de Ciencias, Escuela de Química, Universidad Central de Venezuela |
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Abstract: | Summary: Different kinds of polyethylene and ethylene-1-hexene copolymers were synthesized with TpTiCl2(OR) (Tp = hydrotris(pyrazolyl)borate; R = Et, i-Pr, n-Bu) catalysts with and without H2. The polymers were characterized by 13C NMR, capillary viscosimetry or GPC, and DSC. The homopolymers showed properties characteristic of ultra-high molecular weight polyethylenes (UHMWPE) with linear structure and high density polyethylenes (HDPE) with molecular weights in the range of commercial grades under hydrogen atmosphere. The copolymers showed a 1-hexene incorporation up to 6 mol-%. Important differences in the thermal properties were observed between the first DSC (nascent powders) and the second DSC heatings (melt-crystallized samples), which evidenced the molecular weights influence on the melt-crystallized samples. |
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Keywords: | hydrogen transfer 1-hexene nascent powders polyethylene TpTiCl2(OR) |
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