What you need to know on bonding plastics

For engineers and manufacturers, adhesives have provided the solution when it comes to bonding plastics. With the wide range of adhesives available, it can be challenging to find the right one.

In this post, we share the most commonly asked questions about bonding plastics and how to choose the best adhesive for your application.

What factors do I need to consider when bonding plastics?

It is important to select an adhesive that will have the highest bond strength when it comes to bonding plastic.  The following factors will need to be considered:

  • Type of plastic
  • Physical state and properties of the plastic
  • Chemistry of the plastic
  • Service environment
  • The surface condition of the plastic

What adhesives can I use to bond plastics?

In the industry, the most common adhesives used to bond plastics are cyanoacrylate adhesives, UV curable adhesives, MMAs as well as some epoxy adhesives.

Cyanoacrylate Adhesives (known as instant adhesives) can be used to bond:
Polyolefin polymers such as polyethylene or polypropylene; however, it is recommended to use a primer like Permabond POP prior to application.

UV Curable Adhesives can be used to bond most ABS (acrylonitrile butadiene styrene), Nylon (polyamides), Phenolic, Polycarbonate, PVC (both rigid and flexible).

MMAs (methyl methacrylate adhesives) have a much higher peel strength and temperature resistance compared to epoxy adhesives. MMAs can be used to bond thermoplastics including ABS, PVC (rigid and flexible), acrylic and polycarbonates.

Epoxy Adhesives: particularly one component epoxies are not recommended for bonding plastics where in some cases, the minimum curing temperature of the epoxy resin is higher than the maximum resistance temperature of the plastic. This means the heat required to cure the adhesive will damage the plastic.

Plastics such as PEEK and PBT that have a high temperature resistant may work with special heat cure epoxy adhesives.

Two Component Epoxies or Modified Epoxy Adhesives can be used to bond certain plastics such as acrylic.

What is the best adhesive to bond difficult plastics?

Speciality grade acrylics such as Permabond TA4610 can be used to bond low surface energy plastics such as polypropylene, polyethylene, and other polyolefins.

How do I choose the best adhesive for my application?

There are several factors which you will need to consider before selecting the right adhesive:

Appearance

If the appearance is a high priority, consider using adhesives that provide invisible bonds such as UV plastic adhesives; Permabond UV630 or UV640 or cyanoacrylate adhesives that provide clear bonds. For dark coloured plastics, opt for a cyanoacrylate adhesive with a low odour and low bloom grade; Permabond 940.

Application and cure

For applications that require a fast cure, you may want to consider cyanoacrylate adhesives. UV adhesives can be used for applications that require more time for example, where components need to be accurately aligned.  However, many plastic bonding UV adhesives cure with normal room lighting which means parts will need to be shielded.

Chemical and Temperature resistance of the bond

It is important to know whether your application will need to be solvent or temperature resistant.

The table below provides a guide.

Chemical and temperature resistance of the bond table

For more detailed information on bonding plastics such as ABS, Acetal, Acrylic, PET, PTFE, Phenolic, Polyurethane, Polypropylene, Polyolefin, Polystyrene, PVC, Silicone contact our technical team.

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