Flow induced crystallization of HDPE
Flow induced crystallization of HDPE
(OP)
Hi all,
Recently, I hear about a process called "flow induced crystallization (FIC)".
After some preliminary study, it seems to me that FIC refers to the crystallization of polymer at temperature above its melting point due to the present of shear stress. And this kind of crystallization lead to the formation of Shish Kabab crystal structure.
However, I still have no idea in
1. What's the effect of the Shish Kabab structure on the mechanical properties of HDPE?
2. What's the shear stress (for HDPE) that lead to this kind of crystallization?
3. What's the temperature (for HDPE) for the crystallization to occur?
Could anyone please offer me some help in seeking for the answers for the above questions? (e.g. some books/reference?)
Many thanks,
Recently, I hear about a process called "flow induced crystallization (FIC)".
After some preliminary study, it seems to me that FIC refers to the crystallization of polymer at temperature above its melting point due to the present of shear stress. And this kind of crystallization lead to the formation of Shish Kabab crystal structure.
However, I still have no idea in
1. What's the effect of the Shish Kabab structure on the mechanical properties of HDPE?
2. What's the shear stress (for HDPE) that lead to this kind of crystallization?
3. What's the temperature (for HDPE) for the crystallization to occur?
Could anyone please offer me some help in seeking for the answers for the above questions? (e.g. some books/reference?)
Many thanks,





RE: Flow induced crystallization of HDPE
The only case of sheer induced crystallisation I am aware of is stretching during crystallisation at about the melting temperature like when spinning fibres or when flexing a live hinge where the molecules are drawn into a parallel and tight configuration to bring the intermolecular forces of attraction closer together so stronger tighter crystals quickly form.
Regards
Pat
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RE: Flow induced crystallization of HDPE
RE: Flow induced crystallization of HDPE
For example Google "Dyneema and Spectra shish kebab".
http://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene
Chris DeArmitt - PhD FRSC CChem
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RE: Flow induced crystallization of HDPE
Even though I worked for DSM Engineering Plastics for a number of years, I had never seen the term Shish Kabab structure before with reference to a plastic so I learned something here.
The term I had seen was gel spun PE. I was of the opinion it was a second stage drawing down of the fibre in an autoclave where both the water and the temperature combined to assist in a more tightly packed more oriented crystal structure. I will now look up Shish Kabab structure on google.
Regards
Pat
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RE: Flow induced crystallization of HDPE
Me too!
www.tynevalleyplastics.co.uk
Why be happy when you can be normal?
RE: Flow induced crystallization of HDPE
And I am now looking at the mechanical properties of the following polymer crystal micro-structures.
1. Spherulite of different sizes
2. Elongated spherulite
3. Columnar Crystal & Planar Crystal
4. Shishi Kabab
Hope that I could get a summary on the effect of these structures on the short term and long term behavior of polymer. Any tips for me?
Thanks.
RE: Flow induced crystallization of HDPE
This is starting to sound like you would like us to write your thesis for you.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Flow induced crystallization of HDPE
Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com