| next newest topic | next oldest topic |
| Author | Topic: Copolymer vs. Homopolymer PP |
|
Tom C Moderator Posts: 955 |
posted March 02, 2009 03:31 PM
  
As some of you already know I have and online extrusion calculator found at www.ExtrusionTechnicalServices.com . One curiosity found in developing the calculator was the polypropylene was less efficient than most other polymers studied. Typically polypropylene extrudes at rates 25-30% below that of polymers of equivalent melt density, like polyethylene. This has also been observed by some researchers. I am now looking into some "High Rate" PP screws and note that some are running copolymer PP. Copolymer PP contains some low percentage of polyethylene. The question now becomes are the higher rates due to the screw design, the copolymer, or both? I don't have a lot of data on copolymer polypropylene production rates so I’m asking if anyone cares to share, it would be appreciated. What I need; Thanks for your help.
Tom Cunningham [This message has been edited by Tom C (edited March 02, 2009).] IP: Logged |
|
Makeit Work Senior Member Posts: 8 |
posted July 24, 2009 02:04 PM
We get about 300 pph with a 4.5: 24:1 at 55pms at 3500 psi. DSBM screw MI 4.3 IP: Logged |
|
Tom C Moderator Posts: 955 |
posted July 24, 2009 02:33 PM
Thanks for the feedback. The high back pressure makes it hard to judge. Generally I have found that copolymer PP (PP-C) does not suffer the same loss of rate as homopolymer PP (PP-H). The calculator is set up to reflect that. Calculator found at: Your head pressure is high so that may be reducing your output below the calculator result. The screw might be cut deeper than what optimal for your application. Also at high pressures the screw may deflect resulting in wear, which will reduce the specific output rate.
------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
|
novadan Senior Member Posts: 7 |
posted September 15, 2009 02:22 PM
after reading this post I now no what PP-c and PP-h means on the calculator!!! IP: Logged |
|
Tom C Moderator Posts: 955 |
posted September 15, 2009 03:03 PM
Even after 32 years I am still learning things about extrusion all the time. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
All times are ET (US) | next newest topic | next oldest topic |
  |
|
Contact Us | Feed Screw Designs
Powered by Infopop www.infopop.com © 2000
Ultimate Bulletin Board 5.45a
