Chloe Zhang
The surface energy of a material is a measurement of the disruption of intermolecular bonds. The higher the energy, the more attracted the molecules are to each other, which makes it easier for them to bond with other substances, including adhesives. Materials with high surface energy include many metals and glass. Materials with low surface energy include polyolefin plastics such as polypropylene and polyethylene. High surface energy plastics, or HSE plastics, have surface molecules with high energy levels, which means they require a lower-strength adhesive than low surface energy plastics. HSE plastics include ABS plastics and polycarbonates.
| Characteristics | Values |
|---|---|
| Surface energy | 100s or 1000s of dynes/cm |
| Molecular attraction | High |
| Bonding | Easy |
| Adhesion | Long-term |
| Examples | ABS plastics, polycarbonates, polypropylene, polyethylene |
| Alternative names | HSE plastics |
| Comparison to LSE plastics | Require lower-strength adhesive |
| Comparison to metals | Lower surface energy |
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What You'll Learn
High surface energy plastics are easier to bond with adhesives
The surface energy of a material is a measurement of the amount of disruption of intermolecular bonds. It is a good way to measure how easy or difficult it is for a substance to stick to a surface. The higher the surface energy, the more the molecules in the plastic are attracted to each other. This attraction helps these molecules bond to other substances, including adhesives.
Materials with a surface energy of 36 dynes/cm and below are considered low surface energy materials and are very difficult to bond. Low surface energy plastics such as polyolefin and polyethylene are well-suited to non-stick and other low-adhesive options as it is difficult to bond them. Their utility is better suited to materials that don't need to be bonded or combined with adhesives.
High surface energy plastics, on the other hand, have surface molecules with high energy levels, making them easier to bond with adhesives. They require a lower-strength adhesive than low surface energy plastics since they can be easily "wetted out". This means that the adhesive spreads out, creating an even layer across the entire surface. High surface energy plastics tend to allow easy bonding and long-term "stick" to adhesives. This is thanks to the high molecular attraction inherent in their chemical structure.
Engineered plastics are a common example of high surface energy plastics. They are very common in manufacturing due to their low cost, strength, sturdiness, lightweight nature, and ease of moulding into complicated shapes. They have higher surface energies than low surface energy plastics, making them easier for tapes and adhesives to wet out and bond.
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Low surface energy plastics are difficult to bond
Low surface energy plastics, or LSE plastics, include materials such as polypropylene (PP), polyethylene (PE or HDPE), polystyrene, acetal, EVA (ethylene vinyl acetate), and powder-coated paints. They are generally soft and have a low melting point, making them easy to process and mold, even in high volumes. They are also low-density, aiding in lightweighting. However, their low surface energy makes them difficult to bond.
The surface energy of a material refers to the chemical makeup that influences its level of molecular attraction. Low surface energy materials have a weak potential attraction, resulting in a non-receptive layer that hinders the formation of strong chemical bonds with adhesives. While mechanical bonds can form with the pits and grooves on the surface, they often lack the strength to hold materials together.
The difficulty in bonding LSE plastics has led to the development of specialty adhesives, such as primers and structural acrylics, which can form strong chemical bonds with these plastics. Primers, for example, create a new layer for adhesives to bond with. However, priming introduces complexities and may involve harmful chemicals. Structural acrylics, on the other hand, can be applied manually or via automated equipment and do not require surface treatment to bond with polyolefins.
Additionally, double-sided acrylic foam tapes have been engineered specifically for low surface energy substrates, creating long-lasting and high-strength bonds without the need for primers or promoters, reducing production time. These bonding solutions enable the design of lighter and stronger products with improved aesthetics and environmental resistance.
While bonding LSE plastics poses challenges, advancements in adhesives technology, such as pressure-sensitive adhesives, offer viable options for creating strong bonds with these materials.
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$15.87
Surface energy is measured in dynes per centimetre
Surface energy is a measure of the excess energy present at the surface of a material, in comparison to its bulk. It is a relative measurement of the energy at the surface resulting from incomplete bonding. Liquids will often have lower surface energies than solids due to the weak forces interacting between molecules, which is why liquids usually spread out.
The surface energy of materials can be classified as high, medium, or low. Materials with a surface energy of below 36 dynes/cm are considered low surface energy and are very difficult to bond. Materials with a surface energy of 36 dynes/cm up to about 300 dynes/cm are considered to have medium surface energy. Materials with a surface energy of 100s or 1000s of dynes/cm are considered to have high surface energy and include many metals and glass.
Surface energy is typically measured indirectly with contact angle measurements, which can be a useful qualitative measure. Contact angle measurements assess the wettability of a surface by measuring the angle between a liquid droplet and the surface. A low contact angle indicates a strong interaction between the liquid and the surface, while a high contact angle indicates a low interaction. Liquids with known surface tension are used to ensure the accuracy and reproducibility of measurements.
The spreading coefficient measures the tendency for a liquid to wet on a solid, where wetting occurs for positive values. The higher the surface energy, the more a drop of water spreads out over the surface. Adhesives perform similarly to water on these surfaces.
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High surface energy plastics are often used for reusable containers
The surface energy of a material refers to the chemical makeup of a material that influences its level of molecular attraction. High surface energy materials have a strong intermolecular bond and are therefore easily attracted to liquid molecules. This makes them relatively easy to wet out and, in turn, to bond. Materials with a surface energy of 40 dynes/cm or more are considered high surface energy materials. Many metals and glass fall into this category, but some plastics do as well.
High surface energy plastics include ABS plastics and polycarbonates. These plastics tend to allow easy bonding and long-term adhesion to adhesives. This is thanks to the high molecular attraction inherent in their chemical structure. The high surface energy of these plastics provides quite a bit of utility for projects that require a wide-spreading adhesive that has a lot of staying power.
The surface energy of a plastic can be raised using several surface treatment methods. For instance, LDPE plastics can be treated with plasma for five minutes to nearly double their surface energy. This can be useful when trying to label plastic containers, as plastics with low surface energy are more difficult to label.
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High surface energy plastics include ABS plastics and polycarbonates
The surface energy of a material refers to the chemical makeup of a material that influences its level of molecular attraction. High surface energy materials have a strong intermolecular attraction, which makes them relatively easy to wet out and bond. Materials with high surface energy include many metals and glass, with glass ranging between 200 and 300 dynes/cm and aluminium at 840 dynes/cm.
ABS plastics are also known as amorphous plastics and have long been used in bonding. Polycarbonates have an energy rating of 42 dynes/cm, which is slightly above the dividing line between low and high surface energy levels of 40 dynes/cm.
Low surface energy plastics, such as polyolefin and polyethylene, are well-suited to non-stick and low-adhesive applications as they are difficult to bond. However, advances in adhesives technology have made it possible to bond low surface energy materials, although it is still more challenging than with high surface energy plastics.
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Frequently asked questions
High surface energy (HSE) plastics are plastics with surface molecules that have high energy levels. They are generally easy to bond with adhesives. HSE plastics have a surface energy of 38 or above. Examples of HSE plastics include ABS plastics and polycarbonates.
High surface energy plastics are easy to bond with adhesives, which makes them useful for projects that require a wide-spreading adhesive. They are also sturdy and can be easily moulded into complicated shapes.
Some examples of high surface energy plastics include ABS plastics, polycarbonates, and polyvinyl chloride (PVC).
