Which Glues Work for Polycarbonate Plastic

Polycarbonate is a modern plastic material with many beneficial properties, namely its high optical clarity, and great durability. It is visually similar to glass, but thirty times more impact-resistant, making it as strong as some metals. Consequently, there are many use cases for polycarbonate, such as a replacement for security windows, or tiny non-conductive parts for machinery.
Regular solvents won’t adhere to polycarbonate. In fact, standard household glues may cause polycarbonate to undergo “crazing,” which occurs when chemicals break down the polymer’s microscopic bonds, causing small, crack-like streaks. While this won’t damage the polycarbonate significantly, it will create an unseemly appearance.
Thankfully, there are many effective methods for gluing, or fusing, polycarbonate plastic. Gluing and fusing are not exactly the same, however. While glues leave an adhesive behind, fusing causes a chemical reaction that allows the polycarbonate to melt back together. This is similar to the processes used to glue acrylic plastic.
Each of these bonding and fusing agents have different chemical properties, which may be ideal for different use cases. Let’s go over four common methods used to repair, bond, or fuse polycarbonate plastic.
polycarbonate adhesives

How to Prepare Polycarbonate Plastic for Gluing

Before polycarbonate can be glued, it’s important to ensure it is free of contaminants. First, rinse the polycarbonate with lukewarm water to remove any dirt, sand, or other hard materials that could damage the polycarbonate by scraping against it. Then, combine lukewarm water with a small amount of dish soap. Dip a clean sponge or cloth into the mixture, and gently rub the polycarbonate to remove any small contaminants. Then, rinse the polycarbonate again. At this point, your polycarbonate will be ready for gluing.

Gluing Polycarbonate with Methyl Methacrylate

The most commonly recommended way to fuse polycarbonate is with methyl methacrylate since it creates a strong, resilient bond. Some users have found that if they try to mechanically pull polycarbonate apart, the unaltered polycarbonate will break before the bond will! However, this product is rather niche, and may not be readily available unless the user orders it online ahead of time.

When applying methyl methacrylate, make sure you’re either outdoors, or in a very well-ventilated room. The fumes from methyl methacrylate can be toxic if inhaled in high concentrations. Then, follow these steps:

  1. Take a clean piece of polycarbonate, and lightly apply the methyl methacrylate to the area you’d like to join.
  2. Let the methyl methacrylate soak for a minute. Give it a light tap with a clean piece of metal or wood – if the plastic feels sticky, it’s ready to bond.
  3. Attach the polycarbonate to another piece of polycarbonate, and hold them tightly until they can support their own weight. The timing may vary, but this should take about five minutes.
  4. Once the polycarbonate can support its own weight, let it set for 48 to 72 hours. Then, it should be fully joined.

Gluing Polycarbonate with Superglue

Superglue, also known as a cyanoacrylate adhesive, is another effective way to join polycarbonate. Although methyl methacrylate makes a better quality bond, superglue is much more accessible to the average user. It also bonds faster than methyl methacrylate, making it ideal for quick fixes.
When bonding polycarbonate with superglue, make sure that you’re working in a well-ventilated room. The fumes from cyanoacrylate can be toxic if they are inhaled in high quantities. Don’t apply too much superglue, as it can cause adverse chemical reactions like crazing or blooming. Finally, do not submerge any polycarbonate that is bonded with superglue, since this will cause the superglue’s bond to weaken.
When bonding polycarbonate with superglue, follow this procedure:

  1. Apply the cyanoacrylate to a clean sheet of polycarbonate on the edges that will be joined.
  2. The adhesive will be ready to bond immediately – within a minute of applying the glue, hold the pieces of polycarbonate together until it can support its own weight. This may take a minute
  3. Let the superglue dry for 48 hours before putting any significant pressure on it.

Using Epoxy to Glue Polycarbonate

Epoxide glue, also known as epoxy, is a simple way to glue polycarbonate together. This is commonly used for quick fixes, or for bonding the polycarbonate to materials like ceramic. While epoxy is suitable for some use cases, it’s not necessarily the best general gluing method. It is likely to leave marks from its application, and only provides a slightly stronger bond than superglue. Epoxy is not recommended for outdoor use since it will yellow with continued exposure to UV rays.
Gluing polycarbonate using epoxy is rather simple. Just follow these steps, and make sure you are outdoors or in a well-ventilated room:

  1. If using two-part epoxy, mix the two parts together by following the instructions on the back of the packaging.
  2. Apply epoxy to a clean part of the polycarbonate that you would like to glue.
  3. Hold another piece of polycarbonate to it for about five to ten minutes, or until the bond is firm.
  4. Allow it to sit for 72 hours before putting it under any stress. It may take up to a week for the epoxy to fully dry.

Bonding Polycarbonate with Polyurethane

You can bond polycarbonate with another kind of plastic: Liquid polyurethane. Polyurethane is ideal for low temperatures – as low as -40F – as it will not become as brittle as other forms of adhesives. It’s also highly resistant to many kinds of chemicals, like gas, oil, and salt. If you’ve ever used classic, brand-name Gorilla Glue, then you’ve used polyurethane glue before.
While the bond will not be totally clear, or as strong as methyl methacrylate, many people are drawn to polyurethane due to its physical properties. To glue polycarbonate using this material, make sure you’re in a well-ventilated area. Then, follow this procedure:

  1. Apply the glue to a clean section of the polycarbonate using the applicator or a foam brush.
  2. Hold the polycarbonate together until it begins to join – this may take a few minutes.
  3. Once it can support its own weight, leave it to dry for 24 to 48 hours. Even if the polyurethane is dry, it is not yet ready for demanding use cases.
  4. After about a month, the polyurethane will be perfectly cured and hardened, allowing it to withstand regular use without splitting.

Final Thoughts

Whether you’re looking to create a structure out of polycarbonate, or you’d like to repair a cracked polycarbonate panel, the process to glue polycarbonate is simple. However, each method has its own strengths and weaknesses, think about which kind of bond will be most beneficial to your use case. With the right gluing process, your polycarbonate product will stay sturdy for years to come.
Looking to purchase polycarbonate for your next project? Take a look at our selection of polycarbonate products, or contact us for custom orders.