Have you ever tried sticking tape to a surface only to watch it curl off the surface again?
One reason might be that you’re working with low surface energy substrates, A.K.A. that annoying material refusing to hold your adhesive. In fact, knowing how to bond an LSE surface could be essential to your project.
As an adhesive tape converter, Strouse understands how different materials form adhesive bonds. Today, we’ll help you recognize which materials suit your project and how to handle poor adhesion by giving examples of low surface energy substrates.
What is Surface Energy, and Why Does it Matter?
Surface energy quantifies the molecular attraction between bonds and determines the ease of adhesively bonding two objects. The strength of a substrate’s “sticking power” depends on the level of its surface energy.
HIGH SURFACE ENERGY VS. LOW SURFACE ENERGY
In manufacturing, surface energy is often used to describe the difficulty of adhering to a particular material. Metals and glass tend to have high surface energies and are easier to bond, unlike plastics, which have low surface energies.
- High Surface Energy (HSE): Substrates with high surface energy are easy to bond to because the high-energy surface has a strong molecular attraction to the adhesive’s molecules.
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- They allow the adhesive to “wet out,” i.e., spread across the surface to achieve a stronger bond.
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- Low Surface Energy (LSE): Substrates with low surface energy are challenging to bond to and may require specific adhesives or treatments.
While surface energy is the most prominent factor in determining a material's adhesive bondability, external factors such as surface cleanliness, texture, and permeability can also affect it.
9 Types of Low Surface Energy Substrates
LSE materials are known for being challenging to bond with adhesives. If you use these materials, anticipate limited adhesive options and potential surface treatments.
1. POLYTETRAFLUOROETHYLENE (PTFE) / TEFLON
PTFE is a heat and chemical-resistant, high-performance fluoropolymer (plastic) used in non-stick surface and surgical applications. It can also be used as a high-temperature seal or an electrical insulator.
Teflon is a brand name for PTFE, which is used as a coating agent in everything from non-stick cookware to aircraft components to catheters.
2. SILICONE
Silicone is a heat-resistant synthetic polymer with rubber-like properties. It’s often used in electronic equipment (like circuit boards and computer chips), medical devices (tubing and adhesives), and automotive applications (silicone gaskets, coatings, and varnishes).
3. POLYETHYLENE (PE)
Polyethylene, commonly known as the most common plastic, is used as a film in packaging and molded into containers (thanks to its thermoplasticity). PE is low-temperature resistant but easily processable and has a high chemical inertness.
4. POLYPROPYLENE (PP)
Polypropylene is a heat, solvent, and chemical-resistant thermoplastic polymer used in the packaging, medical, and automotive industries. It’s also known for its inexpensive cost, moldability, and moisture resistance.
5. POLYSTYRENE
Polystyrene is a lightweight, heat and moisture-resistant polymer that comes as a foam, film, or hard, brittle surface. It has a wide range of potential uses, from electronic housings to medical culture trays and diagnostic components.
6. NYLON
Nylon is a lightweight and durable thermoplastic often used in automotive and electronic applications. Nylon polymers are challenging to bond adhesively because they’re chemically inert and absorb water from the air, changing how the additives react with the film's surface.
7. POWDER COATED PAINTS
Powder-coated paints are a common protective coating, however, low surface energy additives can flow to the surface and make bonding a challenge.
8. ACETAL (POLYOXYMETHYLENE/POM)
Acetal is a low-moisture-absorbing thermoplastic with robust dimensional stability. In manufacturing, acetal plastic is shaped into machine parts, but in the automotive or electronic industries, it may serve as connectors, gear wheels, fasteners, or other shaped parts.
9. ETHYLENE VINYL ACETATE (EVA)
EVA is a polymer with rubber-like qualities that comes as packaging sealant, resin, or foam. It is often used as padding in sports equipment.
Whew! Those were a lot of LSE substrates, but you should know that there are plenty of others, including:
- Glass
- Iron oxide
- PVC
- EPDM foams
- Thermoplastic olefin (TPO)
- Thermoplastic elastomers (TPE)
How To Prepare for LSE Bonding
Considering the number of LSE plastics, avoiding low surface energy materials isn’t always a feasible option. So, what’s the best way to prepare yourself for LSE bonding?
Your best bet at a successful LSE solution is to provide a converter with a sample of your substrate for further adhesive testing.
There are millions of different substrates and an enormous range of adhesive tape variants to match them. Testing will help you confidently determine which adhesives best suit your application.
If you’re interested in testing sample parts for a design, contact Strouse so we can help you decide the best adhesive to match your substrate. Lastly, check out our Learning Center for more information on the materials discussed.
