×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Flow induced crystallization of HDPE

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,

RE: Flow induced crystallization of HDPE

I never really heard of this.

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
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

Using Pat's term "shear induced crystallization HDPE" returned a plethora of scholarly articles from a Google search.

RE: Flow induced crystallization of HDPE

The Shish Kabab structure has a huge effect on properties. Look up Dyneema and Spectra properties and compare them to normal PE.

For example Google "Dyneema and Spectra shish kebab".

http://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

RE: Flow induced crystallization of HDPE

Chris

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
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

Quote (Pat)

I had never seen the term Shish Kabab structure before with reference to a plastic so I learned something here.

Me too!

www.tynevalleyplastics.co.uk

Why be happy when you can be normal?

RE: Flow induced crystallization of HDPE

(OP)
Thanks for replying. Now I realize that Shish structure improve the properties of polyethylene (i.e. in UHMWPE)

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

Are you a student.

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

Don't forget to look at transcrystallinity (also known as epitaxial growth). That has a huge effect on properties.

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources