Copolymerization of propylene with Si-containing α,ω-diolefins: how steric hindrance of diolefins affects long chain branch formation

2016 ◽  
Vol 7 (17) ◽  
pp. 2938-2946 ◽  
Author(s):  
Bin Wang ◽  
Yi-Ming Zhang ◽  
Zhe Ma ◽  
Li Pan ◽  
Shi-Jun Yu ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Branch Formation ◽  
Formation Efficiency ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

A series of long chain branched isotactic polypropylenes (LCBPPs) were in situ synthesized by copolymerization of propylene with diallylsilanes. The substituent groups can efficiently suppress the cyclization of the diolefin and significantly improve LCB formation efficiency.

Kinetics of Long-Chain Branch Formation in Polyethylene

ACS Catalysis ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 725-737 ◽  
Author(s):  
Michael D. Jensen ◽  
Qing Yang ◽  
Youlu Yu ◽  
Max P. McDaniel
Keyword(s):  
Branch Formation ◽  
Kinetics Of ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

Revisiting the long-chain branch formation mechanism in metallocene catalyzed polyethylenes

2013 ◽  
Vol 4 (13) ◽  
pp. 3774 ◽  
Author(s):  
Vahid Karimkhani ◽  
Faramarz Afshar-Taromi ◽  
Saeed Pourmahdian ◽  
Florian J. Stadler
Keyword(s):  
Formation Mechanism ◽  
Branch Formation ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

Alternative View of Long Chain Branch Formation by Metallocene Catalysts

2010 ◽  
Vol 43 (21) ◽  
pp. 8836-8852 ◽  
Author(s):  
Qing Yang ◽  
Michael D. Jensen ◽  
Max P. McDaniel
Keyword(s):  
Alternative View ◽  
Metallocene Catalysts ◽  
Branch Formation ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

Resolving long-chain branch formation in tandem catalytic coordinative chain transfer polymerization of ethylene via thermal analysis

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Davood Hassanian-Moghaddam ◽  
Seyed Mohammad Mahdi Mortazavi ◽  
Saeid Ahmadjo ◽  
Mona Doveirjavi ◽  
Abbas Rahmati ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Chain Transfer ◽  
Branch Formation ◽  
Chain Transfer Polymerization ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

Role of molecular architecture in interfacial self-adhesion of polyethylene films

2017 ◽  
Vol 33 (3) ◽  
pp. 235-261 ◽  
Author(s):  
Zahra Najarzadeh ◽  
Abdellah Ajji
Keyword(s):  
Molecular Weight ◽  
Adhesion Strength ◽  
Film Surface ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Molecular Architecture ◽  
Melt Temperature ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

The influence of molecular architecture on interfacial self-adhesion above polyethylene film melt temperature was examined in this study. The investigated molecular structures include molecular weight (Mw), molecular weight distribution, long chain branch amount and distribution and short chain branch among and along polyethylene chains. The long chain branches concentration was quantified using gel permeation chromatography and short branches concentration using nuclear magnetic resonance techniques. The adhesion strength was measured immediately after melt bonding using a T-Peel test. The results showed that increasing Mw resulted in higher adhesion strength in linear metallocene ethylene α-olefins. Low long chain branch concentrations hinder reptation motion and diffusion, and result in lower adhesion strength. Low density polyethylene with highly branched chains yielded very low self-adhesion. A drastic difference in adhesion strength between metallocene and conventional linear low density polyethylene is attributed to homogeneity versus heterogeneity of composition distribution. The low interfacial self-adhesion in conventional polyethylene was concluded to be due to enrichment of highly branched low molecular weight chains at the film surface. These segregated chains at the interface diffuse before the high molecular weight chains located in the bulk.

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