ZHANG Tianyi, XIA Xianzhi, LIU Yuexiang. Effect of pre-contact temperature on performance of DQC spherical catalyst in propylene polymerization[J]. CIESC Journal, 2017, (4): 1434-1441.
ZHANG Tianyi, XIA Xianzhi, LIU Yuexiang. Effect of pre-contact temperature on performance of DQC spherical catalyst in propylene polymerization[J]. CIESC Journal, 2017, (4): 1434-1441.DOI: 10.11949/j.issn.0438-1157.20161119.
The pre-contact temperature of DQC catalyst system on liquid bulk polymerization of propylene was studied using cyclohexyl methyl dimethoxy silane (C-donor) as external donor. The results indicated that increase of pre-contact temperature caused decrease of polymerization activity of DQC catalyst
which yielded polymers with decreased melt index but increased isotactic index and fine powder content. Gel permeation chromatography (GPC) results showed that increase of pre-contact temperature broadened molecular weight distributions and decreased both number and weight average molecular weights. Differential scanning calorimetry (DSC) results exhibited that melting temperature
melting enthalpy
crystallization enthalpy
and crystallinity of polypropylenes increased to various degrees. 13C NMR results showed an increase of stereoregular sequences of triad mm and pentad mmmm with increase of pre-contact temperature.