TY - JOUR
T1 - Molecular heterogeneity of metallocene short-chain branched polyethylenes and their fractions
AU - Fu, Qiang
AU - Chiu, Fang Chyou
AU - He, Tianbai
AU - Liu, Jieping
AU - Hsieh, Eric T.
PY - 2001/4/18
Y1 - 2001/4/18
N2 - A comparison on the molecular heterogeneity of two whole metallocene short-chain branched polyethylenes (SCBPEs) with different hexene comonomer (butyl branching) content and their Cross-Fractionated (CF) fractions has been made. As elucidated by differential scanning calorimetry (DSC) thermal segregation experiments and the subsequent isothermal crystallization kinetics investigations, the whole metallocene SCBPEs, were found to possess both inter- and intramolecular heterogeneity. The crystallization kinetics of whole SCBPEs are substantially different for samples with or without a premultiple-step annealing treatment. For the CF fractions, the inter-molecular heterogeneity exists. Nevertheless, another self-induced SCBPE fraction, as a model sample, shows good homogeneity both inter- and intramolecularly. The crystal morphology observed via transmission electron microscopy (TEM) shows that multiple-step crystallized whole polymers exhibit large scale (molecularly) phase separation, whereas the CF fractions demonstrate microscopic (segmental) segregation only.
AB - A comparison on the molecular heterogeneity of two whole metallocene short-chain branched polyethylenes (SCBPEs) with different hexene comonomer (butyl branching) content and their Cross-Fractionated (CF) fractions has been made. As elucidated by differential scanning calorimetry (DSC) thermal segregation experiments and the subsequent isothermal crystallization kinetics investigations, the whole metallocene SCBPEs, were found to possess both inter- and intramolecular heterogeneity. The crystallization kinetics of whole SCBPEs are substantially different for samples with or without a premultiple-step annealing treatment. For the CF fractions, the inter-molecular heterogeneity exists. Nevertheless, another self-induced SCBPE fraction, as a model sample, shows good homogeneity both inter- and intramolecularly. The crystal morphology observed via transmission electron microscopy (TEM) shows that multiple-step crystallized whole polymers exhibit large scale (molecularly) phase separation, whereas the CF fractions demonstrate microscopic (segmental) segregation only.
UR - http://www.scopus.com/inward/record.url?scp=0035906422&partnerID=8YFLogxK
U2 - 10.1002/1521-3935(20010301)202:6<927::AID-MACP927>3.0.CO;2-K
DO - 10.1002/1521-3935(20010301)202:6<927::AID-MACP927>3.0.CO;2-K
M3 - 文章
AN - SCOPUS:0035906422
SN - 1022-1352
VL - 202
SP - 927
EP - 932
JO - Macromolecular Chemistry and Physics
JF - Macromolecular Chemistry and Physics
IS - 6
ER -