×
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

Why Polypropylene is so difficult to Bond ?

Why Polypropylene is so difficult to Bond ?

Why Polypropylene is so difficult to Bond ?

(OP)
I want to Bond PP to Brass,but not able to get suitable solution. Everybody knows PP is difficult to bond substrate due to inert nature.  

Friends Can you please help me in understanding the chemistry why PP is difficult to bond and what are the best ways of bonding it.

Thanks
Smita

RE: Why Polypropylene is so difficult to Bond ?

One suggestion. You can strive for mechanical bond by melting the PP to the brass piece.  Drill some small holes in your brass piece on the side which you want the PP to be bound.  Heat the brass piece to above the melting temperature of PP.  Then just take the hot brass piece and press it down on the PP under pressure until it cools.  Some of the Melted PP should get into the small holes, and the brass will then constrict around the PP sprews as it cools.  All of this could be done with a blow torch and a drill press (depending on how sensitive your pieces are.) Hope it helps.  If this is going to be a throughput product or product piece, I suggest using a commercially available heat stamper.  Cheap, tight controls, and fast.  More generally used for stamping of logos into polymer surfaces, using heat and pressure.  If interested, check out www.stampritemachine.com

aspearin1

RE: Why Polypropylene is so difficult to Bond ?

Polypropylene is difficult to bond to because the polymer has no polar or chemically reactive groups. The surface is very low energy like parafin wax, which is chemically similar. The surface can be chemically etched with very reactive chemicals or treated with a flame or plasma (corona treatment). Bonds are still likely to be weak or unreliable.

The sugestion to get mechanical bonding is a good one. I have found that it is usually better to have raised barbs rather than holes. These melt and penetrate plastic with little flow being required. To get the polymer to melt at the surface and then flow though a hole is much more difficult.

A useful technique is to spot weld a woven or knitted wire mesh to the metal suface. Heat the metal object above the melting point of the plastic and press the plastic part onto the metal one. As the plastic melts the metal cools and the bonding is complete in ten or twenty seconds.

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