Highly active self-immobilized FI-Zr catalysts in a PCP framework for ethylene polymerization

2015 ◽  
Vol 51 (93) ◽  
pp. 16703-16706 ◽  
Author(s):  
He Li ◽  
Bo Xu ◽  
Jianghao He ◽  
Xiaoming Liu ◽  
Wei Gao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Ethylene Polymerization ◽  
Highly Active ◽  
Catalytic Performances

FI catalysts in PCPs show good catalytic performances and produce high molecular weight polyethylenes with bimodal molecular weight distribution.

Asymmetric bis-salicylaldiminato binuclear titanium complexes for ethylene polymerization and copolymerization

2021 ◽  
Author(s):  
Yawen Qin ◽  
Tingcheng Li ◽  
Xiong Chen ◽  
Jian Li ◽  
Xiang Meng ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Ethylene Polymerization ◽  
Titanium Complexes ◽  
Broad Molecular Weight Distribution

Polyolefins with high molecular weight and broad molecular weight distribution have attracted great attention due to their ease of processing and wide applications. In this paper, methylene-bridged asymmetric disalicylaldimine ligands...

Chromium complexes supported by the bidentate PN ligands: synthesis, characterization and application for ethylene polymerization

2018 ◽  
Vol 47 (38) ◽  
pp. 13459-13465 ◽  
Author(s):  
Quande Zheng ◽  
Dejuan Zheng ◽  
Binghao Han ◽  
Shaofeng Liu ◽  
Zhibo Li
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
Chromium Complexes ◽  
Highly Active ◽  
Imine Ligands

Chromium complexes bearing phosphine–imine ligands are highly active for ethylene polymerization and produce HDPE with a high molecular weight.

Equilibrium Molecular Weight Distribution of Cyclic and Linear Methylsiloxanes

1967 ◽  
Vol 40 (4) ◽  
pp. 1084-1093 ◽  
Author(s):  
Jack B. Carmichael ◽  
James Heffel
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Equilibrium Constants ◽  
Molecular Size ◽  
Size Distributions ◽  
Flory Theory ◽  
Molecular Weights ◽  
Cyclic Molecules

Abstract Data are reported for the equilibrium molecular size distributions of cyclic and linear methylsiloxanes in five polymers with number average molecular weights ranging from 459 to 1348. The distributions of linear species agree with the earlier work of Scott and agree reasonably well with the Flory theory of random reorganization. The amounts of cyclic molecules are sharply dependent on molecular weight. However, the equilibrium constants for cyclic formation for cyclic species with four to eight units are shown to be virtually identical with the equilibrium constants for cyclic formation in high molecular weight polymers reported in a previous publication. For octamethylcyclotetrasiloxane, Kav in moles of siloxane units per liter was found to be 0.72 in this study. For high polymers, Kav was previously reported to be 0.74.

Bis(phenolate) N-heterocyclic carbene rare earth metal complexes: synthesis, characterization and applications in the polymerization of n-hexyl isocyanate

RSC Advances ◽  
2015 ◽  
Vol 5 (101) ◽  
pp. 83295-83303 ◽  
Author(s):  
Min Zhang ◽  
Jingjing Zhang ◽  
Xufeng Ni ◽  
Zhiquan Shen
Keyword(s):  
Molecular Weight ◽  
Rare Earth ◽  
Metal Complexes ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Rare Earth Metal ◽  
Weight Distribution ◽  
Earth Metal ◽  
Narrow Molecular Weight Distribution ◽  
Rare Earth Metal Complexes

Polyhexyl isocyanantes catalyzed by N-heterocyclic carbene rare earth metal complexes show high molecular weight with narrow molecular weight distribution.

scholarly journals The Succinyl and Acetyl Modifications of Succinoglycan Influence Susceptibility of Succinoglycan to Cleavage by the Rhizobium meliloti Glycanases ExoK and ExsH

1998 ◽  
Vol 180 (16) ◽  
pp. 4184-4191 ◽  
Author(s):  
Gregory M. York ◽  
Graham C. Walker
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Meliloti ◽  
Low Molecular Weight ◽  
Wild Type ◽  
Mutant Strains ◽  
Acetyl Group

ABSTRACT In Rhizobium meliloti (Sinorhizobium meliloti) cultures, the endo-1,3-1,4-β-glycanases ExoK and ExsH depolymerize nascent high-molecular-weight (HMW) succinoglycan to yield low-molecular-weight (LMW) succinoglycan. We report here that the succinyl and acetyl modifications of succinoglycan influence the susceptibility of succinoglycan to cleavage by these glycanases. It was previously shown that exoH mutants, which are blocked in the succinylation of succinoglycan, exhibit a defect in the production of LMW succinoglycan. We have determined that exoZ mutants, which are blocked in the acetylation of succinoglycan, exhibit an increase in production of LMW succinoglycan. For both wild-type andexoZ mutant strains, production of LMW succinoglycan is dependent on the exoK + andexsH + genes, implying that the ExoK and ExsH glycanases cleave HMW succinoglycan to yield LMW succinoglycan. By supplementing cultures of glycanase-deficient strains with exogenously added ExoK or ExsH, we have demonstrated directly that the absence of the acetyl group increases the susceptibility of succinoglycan to cleavage by ExoK and ExsH, that the absence of the succinyl group decreases the susceptibility of succinoglycan to cleavage, and that the succinyl effect outweighs the acetyl effect for succinoglycan lacking both modifications. Strikingly, nonsuccinylated succinoglycan actually can be cleaved by ExoK and ExsH to yield LMW succinoglycan, but only when the glycanases are added to cultures at greater than physiologically relevant concentrations. Thus, we conclude that the molecular weight distribution of succinoglycan in R. meliloti cultures is determined by both the levels of ExoK and ExsH glycanase expression and the susceptibility of succinoglycan to cleavage.

Sign in / Sign up

Export Citation Format

Share Document