It can be challenging bonding thermoplastic polyolefins like polyethylene and polypropylene. Polyolefins have a low surface energy which makes it difficult for adhesives to wet the surface. The adhesive instead remains as droplets or beads never covering the substrate surface.
Surface treatments such as corona, plasma and flame can increase the surface energy, however they can be expensive, time-consuming and often require handling and storing hazardous materials.
Cyanoacrylates and toughened acrylics offer the best option and are the most commonly used adhesives for bonding polyolefin plastics.
Cyanoacrylate adhesives are single component adhesives that polymerize quickly when pressed into a thin film between parts. The moisture absorbed onto the surface initiates the curing of the adhesive and forms a strong bond.
We recommend pre-treating the polyolefin with Permabond POP before applying the Cyanoacrylate adhesive. This powerful combination will create a bond stronger than the polypropylene or polyethylene substrate in shear, provide a resistance to non-polar solvents such as motor oil and gasoline, however the impact strength may be limited.
Permabond POP and cyanoacrylate adhesives provide a fast and effective solution for most applications.
These adhesives have high shear strength and temperature resistant qualities of an acrylic adhesive, combined with the peel strength and impact resistance of a reactive rubber base. Toughened Acrylic adhesives can be used for applications that require more impact strength or resistance to water and other polar solvents.
Permabond TA4605 and TA4610 are 1:1 mix acrylics that are dispensed from a dual cartridge so require no mixing. TA4605 achieves a handling strength in 25 minutes. TA4610 achieves a handling strength in 50 minutes due to the longer pot life.
Both acrylic adhesives are designed to bond low-surface energy plastics without the need for a primer or surface treatment. They even have some strength in bonding PTFE and silicone rubber.
How to bond polyolefin plastics
Example of Permabond adhesives used to bond different polyolefin plastics