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| Author | Topic: Nylon-ceramic compounding |
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donaloriain Senior Member Posts: 6 |
posted April 23, 2003 10:55 AM
  
I am looking for some advice on twin-screw compounding of a nylon 66-ceramic blend (approx. 60wt.% ceramic). I have heard that you can get severe wear in your barrel/screw if you compound such a formulation incorrectly. Is it necessary to use processing aids or would it be advisable to feed the ceramic downstream? Also is there a coupling agent required for such a compound? IP: Logged |
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Tom C Moderator Posts: 135 |
posted April 23, 2003 11:20 AM
60% Ceramic into the throat with the resin may not run well, and will likely result in high wear. 30% Ceramic in the throat and 30% downstream will likely run better, with less wear. 60% Ceramic downstream may not run well or mix well. Splitting it into two separate 30% downstream feed point would probably be optimal. A coupling agent would be nice to imrove properties, but I'm not sure anything is available for ceramic. A lot depends on particle size for all of this. Tom C IP: Logged |
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donaloriain Senior Member Posts: 6 |
posted April 23, 2003 11:30 AM
Thanks Tom C. I've never considered that option. I'll definitely give it a try. Have you had any experience with this method of filler addition before. IP: Logged |
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Tom C Moderator Posts: 135 |
posted April 23, 2003 01:33 PM
Lots of materials, lots of methods. 25 years in compounding and state of the art twin screw process design, development and problem solving tools. Tom C IP: Logged |
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donaloriain Senior Member Posts: 6 |
posted May 12, 2003 10:16 AM
Back again!! When downstream feeding in a situation such as this is it more advatageous to feed into the top or the side of the barrel? I know that side feeing is generally the norm but do you know is there any major disadvantage to using a top feed (in terms of mixing, etc.)? IP: Logged |
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Tom C Moderator Posts: 135 |
posted May 12, 2003 10:26 AM
Top down stream feeding is possible. It is normally reserved for lab work because problems can occur over the long term. The volatiles tend to make the filler stick to the feed hole and close it off over the long term. For some materials, like talc, the trapped air that is rushing back can make it difficult to directly feed into the top of a barrel. Stuffers and side feeders geneally offer the security that the downstream fed material is being forced intot the extruder. Tom C IP: Logged |
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donaloriain Senior Member Posts: 6 |
posted May 12, 2003 10:42 AM
Thanks for your advice. Again its much appreciated. Hope you don't mind one more query. My twin-screw is only a lab-size and I have mostly used a top-feeder. When doing this I have always created a "seal" (using a reverse feed section) just before the feed port to ensure that molten material doesn't come out of the port. Is such a "seal" necessary with side feeding when you are "stuffing" the filler into the barrel? Also is it best to feed into a standard feed section of the screw as opposed to into a section with mixing paddle? IP: Logged |
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Tom C Moderator Posts: 135 |
posted May 12, 2003 01:27 PM
The only requirement when down stream adding materials is no pressure, unless you can feed under pressure. I don't think you can feed under pressue so you need forwarding screw elements under the addition port. What type of extruder are you running? If you like I may be able to make up a screw drawing easily and post it here. Additionally we could show simulations and discuss it here if you don't mind showing the process publicly. Tom C IP: Logged |
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donaloriain Senior Member Posts: 6 |
posted May 13, 2003 04:51 AM
I would have no problem with you posting screw drawings and/or simulations. That would be a great help. Here are some details which you may need about the extruder I am running. If you need any more let me know. I am running an APV 3/4 inch co-rotating extruder with a 35:1 L/D ratio. This extruder has two ports for side feeding located approx 9in and 15in from the hopper end of the barrel. IP: Logged |
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zabielski Senior Member Posts: 139 |
posted May 13, 2003 07:41 AM
For best adhesion, which result in superior physical properties, I would recommend a definate coupling agent. Try contacting EXXON or CROMPTON. Be very specific with the polymer and ceramic your using. IP: Logged |
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