Plastic raw materials are used in many industrial sectors and are the starting point for a wide range of production processes. They mainly consist of plastic granules and pellets.
In this post, we will analyze the characteristics and differences between granules and pellets. Then, we will propose a classification of plastic granules according to the material they are made of and their behavior during processing. Finally, we will offer an overview of Vismec systems for dehumidifying, transporting, dosing and storing plastic granules.
Plastic raw materials: granules and pellets
Within the field of plastics, the words ‘granules’ and ‘pellets’ are often used interchangeably. However, there are also significant differences between these two types of plastic raw materials, regarding the production method, shape and fields of use.
- Plastic granules are small plastic particles, generally irregular in shape, resulting from crushing processes or the recycling of pre-existing materials. They are used both for ordinary processes and for specific applications, such as the production of technical polymers or bioplastics.
- Pellets, on the other hand, are obtained by extrusion and subsequent cutting of the molten material. Unlike granules, plastic pellets have a regular shape, generally cylindrical. Their regularity makes them ideal for industrial processes that require a precise and constant dosage.
Both are key elements in the plastics production chain: the choice between one or the other format depends on the needs of the production process and the characteristics of the desired product.
The different types of plastic granules: classifications
The classification of plastic granules can be carried out according to different criteria, including their hygroscopic properties and their composition. These aspects also determine the processing conditions and their possible industrial applications.
Hygroscopic and non-hygroscopic granules
A first criterion is based on the granules’ ability to absorb moisture from the environment.
- Hygroscopic granules absorb and retain moisture in their molecular structure: this can compromise their properties during processing, altering the characteristics of the finished product. Consequently, the dehumidification phase before their use in production processes must be extremely effective. The most common hygroscopic materials include polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET) and polyurethane (PU).
- On the contrary, non-hygroscopic granules do not absorb moisture internally but can still retain water on the surface. Polymers such as polyethylene (PE), polypropylene (PP) and polystyrene (PS) belong to this category. So it is easier to manage the elimination of humidity in these materials during the preparation phase for the production process, although they still require drying.
When working with hygroscopic granules, control of the dew point becomes particularly important. The dew point is the temperature at which the humidity present in the air begins to condense. Measuring the dew point, in this case, helps to correctly manage dehumidification, helping to ensure the quality of the finished product.
Classification based on the material
A second classification criterion concerns the material the granules are made of, an element that influences the mechanical and chemical properties of the granule and, consequently, the organization of the production process. Among the most common materials are:
- Polyethylene (PE), used for packaging, pipes and films thanks to its chemical resistance and flexibility;
- Polypropylene (PP), valued for its rigidity and heat resistance, used in sectors such as automotive and packaging;
- Polystyrene (PS), suitable for light applications such as food containers and insulating materials;
- Polyamide (PA), known as nylon, used for gears and technical components thanks to its resistance to wear;
- Polycarbonate (PC), used for applications that require transparency and impact resistance, such as lenses and screens;
- Polyethylene terephthalate (PET), very common in packaging, especially for food;
- Polyurethane (PU), valued for its elasticity, resistance to abrasion and versatility, used in applications ranging from industrial coatings to components.
There are many other raw materials used to make plastic granules: we have listed the main ones.
Vismec machinery for the treatment and management of plastic granules
Drying, transportation, dosing and storage of plastic granules and pellets are essential during the plastic processing stages to ensure the quality of the finished product and production efficiency. Vismec designs systems and machinery for the effective management of these processes, offering customized solutions to optimize performance and reduce costs.
- Drying. We have already mentioned how dehumidification is crucial, as residual humidity in the polymers can compromise the quality and resistance of the final product. Vismec wheel dehumidifiers are innovative and efficient dehumidification solutions with low energy consumption.
- Conveying. The transportation of plastic granules, whether individual or centralised, allows for the automatic distribution of the material to the various processing stations. Vismec pneumatic transportation systems reduce downtime and ensure safe material handling: efficiency and high performance.
- Dosing. Accurate granule dosing allows for a high-quality, homogeneous mixture, especially in applications that require the combination of several polymers or additives. Vismec offers volumetric doser and gravimetric doser systems that ensure perfect control over the quantity of dosed material, avoiding waste and guaranteeing a uniform result.
- Storage of granules and pellets. Vismec offers robust and reliable solutions for the storage of granules and pellets, to preserve the integrity of the material and facilitate its use. The containers are designed to facilitate manual or automatic loading and are made with a modular structure that makes them suitable even for the most demanding industrial applications.
Are you looking for innovative, high-performance systems for managing plastic granules in your company? Contact our team: we will be glad to help you.