Vacuum pumps are used throughout the plastic recycling industry.

They are used in pneumatic conveying to transport the plastic pieces from one area of the plant to another. They are used for degassing in the extrusion process, where the old plastic is melted down and formed into pellets, ready to be turned into something new. And, when the goal is to create new fuel rather than new plastic products, they are used to speed up the pyrolysis process, as well as to remove the toxic gases it creates.

Vacuum pumps have several benefits across the three different methods of plastics recycling.

Mechanical recycling
During extrusion, the use of a vacuum pump improves the quality of the plastic by ensuring that all air pockets are removed.

Chemical recycling
Pyrolysis as a recycling technique takes place under vacuum. This allows a lower temperature to be used and can shorten the process time. Vacuum pumps are additionally used to extract the dangerous gases that are produced. This process saves unrecyclable plastics from landfill.

Physical recycling
Physical recycling also provides a method of recycling unrecyclable or mixed plastics. Shredded plastic is dissolved in a solvent solution. The solvent and any impurities are then evaporated and degassed under vacuum, leaving behind only the polymers in liquid form.

There are three types of plastics recycling processes that use vacuum in one or more stages.

1. Mechanical recycling

Mechanical recycling is the process of separating, grinding, and washing plastic waste before shredding it into flakes or melting and pressing it into pellets. Polymers do not change during this process, so they can be used again and again to create the same product or something similar. Globally, this is the most commonly used method and the simplest and most economical way to recycle plastic materials. It has a lower carbon footprint compared to other processes. Vacuum is used in the extrusion stages of this process.

2. Chemical recycling

Chemical recycling is the most complex and expensive recycling process. The polymer’s chemical structures are altered and reprocessed, so the plastics can be used as virgin materials. Impurities, additives, dyes, and chemical defects are completely removed from the plastic waste. This method is less popular due to the lack of technologies that can reliably alter polymer structures on an industrial scale. Vacuum is used in the extrusion and pyrolysis stages of this process.

3. Physical recycling

During physical recycling, the shredded plastic is dissolved in a solvent solution. The solvent and any impurities are then evaporated and degassed under vacuum, leaving behind only the polymers in liquid form. Unlike in chemical recycling, the polymer chains are not broken, so the plastic is not destroyed. It can therefore be retrieved and used again, without having to begin the process from scratch. This process allows types of otherwise non-recyclable plastic to be recycled. It also makes it possible to recycle mixed plastic waste, which would be difficult or nearly impossible in a mechanical process. By introducing different solvents, different polymer types can be selectively dissolved and recovered.

The very action of recycling plastics is environmentally beneficial. The process helps reduce plastic pollution and conserve resources. This means that wherever vacuum pumps are involved in the plastics recycling industry, they are contributing to the environmental benefit.

In addition, the use of vacuum pumps in the mechanical recycling process ensures higher quality of recycled plastics, which is comparable with plastic made from virgin materials. This means that fewer resources are needed to create new plastics – and fewer newer products are created. The result is a lower CO₂ footprint.

Vacuum degassing has another benefit. The harmful gases that are collected can be reused in other stages of the process. This both increases efficiency and lowers the environmental impact – and makes the conditions in the plastic production facility safer for workers.

Recycled plastic is sold to businesses that use it to create new products, such as plastic bags, food packaging, clothes, furniture, and automotive parts.

Using recycled plastic is a sustainable and cost-effective choice. The availability of recycled material reduces the demand for virgin materials to create new products, thus decreasing greenhouse gas emissions.

Vacuum is used in many stages of the creation of new plastic products from recycled materials, such as pneumatic conveying and degassing.

Mechanically recycled plastics will never have the same properties as virgin plastics. The recycling process reduces their resistance to chemicals, extreme temperatures and impacts. However, how much of an effect this has on their continued usage depends entirely on their application. Most plastic applications do not actually need the strength and resistance that a virgin plastic provides, so recycled plastic is a viable alternative. Consider a shampoo bottle. In normal household use, it is never likely to be exposed to extreme temperatures, to fall from a great height, or to be exposed to high pressure. The properties of a recycled plastic, even though of a lower quality than a virgin plastic, are therefore enough.

However, for more demanding applications, adding a small amount of virgin material to a recycled plastic resin can create a plastic that has almost the same properties and strength as a completely virgin plastic. While this does not entirely eliminate the need for virgin plastics in the supply chain, it still contributes to a significant reduction in their production.

Creating new products from recycled plastic can have different challenges than working with virgin plastic. We are happy to advise you on a solution for any issues your vacuum pumps are facing during your plastics manufacturing or recycling processes.

There are two main types of plastic used in consumer products. The different types are formed differently and therefore must be recycled in different ways.

Thermoplastic

The most easily recyclable type of plastics. Thermoplastics become soft and malleable when heated, allowing them to be molded into different shapes, and harden again when cooled. When a thermoplastic is formed, it does not change its bond structure and can be reheated, recycled and remolded again. Common thermoplastics and their uses include:

Thermoset plastic

A thermoset plastic is created by curing, or hardening, a softened or liquid polymer resin. In the curing process, the polymer chains cross link to form a rigid, unbreakable structure. This means that this process is irreversible, and unlike a thermoplastic, a thermoset plastic cannot be melted down and reformed. Common thermoset plastics and their uses include: