I may be wrong, but most metallocene polyethylenes belong to the short branching and linear types. Long chain braching typically appears in LDPE produced by radical polymerization. Mtallocene polymers involve butene, hexene, octene - leading to short chain branching.

It's not true, hehe~~~

I'm always happy being taught by anyone

Dr.T.Demappa. Mysore University,

Polymer Science Department,

Dear Gyorgy Banhegyi,

Long chain branching happens in LDP through radical polymerization; you are right! but there are several ways to induce Long chain branching in some types of Polyethylene Even HDPE. one of these ways is using special types of Metallocene catalyst specially "CGC's" (Constraint Geometry Catalyst) . This type of catalysts are capable to generate Long Chain branching vis Betta-H elemenation. DOW company in USA is manufactuur of CGC.

Another way to induce Long Chan branching is "Thermo Oxidative Induction" and also by exposing the PE under Gamma radiation you can generate LCB in PE.

Dear Thippaiah Demappa ,

Should I contact Dr.T.Demappa at Mysore University for my request?

Thank you.

Dear Faezeh Rezaie,

Thank you for the informative answer. As you may remeber, I started my note with "I may be wrong" - I answered your question only form the industrial routine. I was involved for some years in the management of a palstics industrial database, where I had to supervise data collected form Eastern an Central European plastics porcessing companies (ChemIT, http://www.ecebd.com/EcebdIndex.aspx?Id=f150405e-bc32-41b7-8edf-609c4bd520af) so my knowledge in this field refelcts the routinely used grades. I presume that long chain branched metallocene polmyers represent a new segment in the industry or are used for special applications. Right now LDPE like charactersitcs are routinely achieved by short chain branching and copolymeriation as well. Is it also possible that long chain branched metallocene polymers became important since the time I stopped working in thsi field.

Bset regards

George

Dear Gyorgy,

Thanks alot for your reply.

If you need more information or some articles in this regard, I can send for you.

All the best,

F. Rezaie

I would appreciate receiving such articles to my email address [email protected]

Thanks in advamce

To return you kindness I made a brief search on this topic with the follwoign results:

http://www.univation.com/downloads/whitepapers/metallocene.pdf

http://www.tappi.org/content/events/10PLACE/papers/halle.pdf

http://www.dow.com/polyethylene/global_news/2011/20110404a.htm

http://www.plastindia.org/upload%5Cinternationalconference%5Cday2%5CDr.%20Ann%20M.Schoeb-Welters,%20Univision%20Technologies%20LLC.pdf

It seems that Exxon and Dow both produce such materials

Dear Gyorgy,

I really appreciate your kind attention and follow up. Yes, you are right ; but I'm not sure if I can request for the sample of catalyst from these companies.I heard that these companies do not disclose their technology.

Anyway, I will try to send Email for my request to them.

Thank you so much again.

with kind regards,

F. Rezaie

Agreed:) catalyst technology is the key for success - you may obtain it by paying heavy license

Polyethylene with long chain branches can be prepared by using Ziegler - Natat catalysts by copolymerisation with 1- hexene or 1- octene etc. I suppose reliance Industries in India is involved in the manufacture of such polymers. Mettallocenes have not been commercialised yet I suppose