How do you bond plastic sheets together?

Gluing vinyl on melamine

Why should you have polycarbonate glue at home? You will be surprised to know how many household items can be repaired with this adhesive. In this article we show you all its possibilities.

It is not simply a glue for honeycomb polycarbonate used in construction, as its name might suggest, but this adhesive can also be used on many other objects made of this and other materials. Without going any further, you can use it to repair wood, glass, metal or most plastics.

Self-adhesive sheets for flooring

Bonding on plastics or elastomers is more complex than other types of bonding such as metal. The reason is that at industrial level plastics contain by-products such as plasticizers, antioxidants, various additives and traces of release agents that can have a negative effect on the bond.    The polarity of the plastic and its surface energy is basic to achieve a good bonding, materials with low wetting such as PE and PP will present more complications when bonding.

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It is essential to degrease the surfaces to be bonded. For this purpose, the products to be used will vary depending on the type of plastic we are dealing with. The most common products are acetone for PE and PP, isopropyl alcohol for PC, etc.

Single-component epoxy adhesives are not the best choice for one simple reason: the curing temperature of the epoxy resin is higher than the temperature resistance of the plastic itself. That is why before choosing this type of adhesive we must be clear about the resistance of the plastic in question.

How to bond plastic with heat

Polypropylene can be difficult to bond due to its very low surface energy or wettability. A surface is wettable when liquids such as water can spread along its length without droplets accumulating. High surface energy materials, such as phenolics, are easier to bond than low surface energy materials because the adhesive can flow and wet the entire substrate, ensuring consistency in bond strength across the entire surface. In general, a material must have a surface energy greater than 36 mJ/m² in order to bond. The surface energy of a material can be improved by using surface treatment methods such as primers, flame, corona and plasma. The table below shows a range of materials along with their surface energies:

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Permabond 105 is a low viscosity cyanoacrylate adhesive that is naturally best suited for difficult to bond plastics such as polypropylene. It is a high purity adhesive that is 100% reactive and capable of developing strong bonds extremely fast on a wide variety of substrates. It is also easy to use, requiring no mixing or heat curing.

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Self-adhesive wall sheeting

There are other adhesives, such as wood glue or carpenter’s glue, that do not react as expected when applied to hard, high-density synthetic surfaces. This is the case for objects such as buckets, boxes and other containers. Hard plastics are made of polyethylene (indicated with a 2 or “HDPE”) or polypropylene (indicated with a 5 or “PP”) and if we have to work with them, it will be necessary to find an adhesive that guarantees the durability and effectiveness of the fixing.