Plastic granulate – what is it and what is it used for?
Last updated: 04 February 2026
Plastic granulate, or plastic pellets, is a fine-grained starting material used in plastic processing. These small, uniformly shaped elements form the foundation for a wide variety of plastic products, such as pharmaceutical primary packaging, medical components, or laboratory items. The hallmark: the grains have a defined geometry. Their diameter is usually 2 to 5 millimeters, which guarantees optimal flowability and dosing.
Good to know: So-called aseptic filling using Blow-Fill-Seal technology (BFS) processes the granulate in a continuous process directly into sterile containers, which are immediately filled and hermetically sealed – ideal for sensitive contents such as medicines, food, or vaccines.
The pellets can be obtained from a wide variety of types of plastic. Both polyethylene (PE), such as LDPE and HDPE, and polypropylene (PP) are among the standard materials for BFS primary packaging.
How exactly can plastic pellets be produced?
Three central steps are necessary for the production of plastic granulate:
Polymerization: At the beginning of production, a chemical synthesis called polymerization takes place. The principle: the small individual starting components combine to form long, stable polymer chains. This step takes place at the raw material manufacturer. For aseptic filling at Rommelag, certified pharma-grade granulate is used, which is delivered already granulated.
Additivation: In the next step, the polymer comes into contact with so-called additives. These are various additions such as dyes, plasticizers, fillers, or stabilizers. They specifically influence and change the properties of the material required for the planned further processing. For example: if red granulate is required for later production, the manufacturer intentionally adds red dye to the material, which is particularly the case with consumer goods. Pharmaceutical production, however, especially in the case of aseptic packaging solutions such as those from Rommelag, consistently minimizes the use of additives to prevent the risk of migration substances (leachables) into the medicinal product. Transparency clearly takes precedence in the pharmaceutical sector to enable reliable automated optical inspection (AOI) of the filled containers.
Granulation: Next, the molten polymer enters a special nozzle that divides it into fine, uniform strands. The manufacturer then allows the individual strands to cool thoroughly and cuts them into small pieces. And it is precisely these small pieces that form the plastic granulate, which can then be used as desired in plastic processing.
What properties characterize plastic pellets?
The granulate is defined not only by its standard shape but also by its standardized bulk density and grain size distribution. If it meets these standards, it can be used and processed without any problems. But what properties have made the material indispensable in the plastics industry?
- Quality assurance: The standard production of the granulate ensures uniform quality. And the more uniform the quality, the more uniform the end product.
- Excellent flowability: The uniform granulate geometry enables precise, automated dosing and conveying in the extrusion unit.
- Durable product: As a rule, the granulate is storage-stable. Depending on the type of polymer, however, it must be protected from moisture or dried before processing.
- Diversity: The versatile starting material has proven itself in a wide variety of areas – whether in the automotive industry, electronics, the construction industry, or toy manufacturing.
Common application areas of plastic granulate
- Extrusion: The robust material is suitable for extrusion processes. In other words: the heated granulate moves through a mold to produce products such as films, pipes, or fibers.
- Blow molding: Manufacturers also frequently rely on plastic granulate as a starting material for hollow bodies such as bottles and containers. In pharmaceutical manufacturing, such as at Rommelag, the Blow-Fill-Seal process (BFS) has become established, whereby containers are created directly from the granulate. The advantage: due to the high extrusion temperature, the material undergoes a significant thermal reduction in germs, which forms the basis for asepsis in the BFS process.
- Injection molding: The granulate stands out particularly in injection molding. Here, the producer heats the material and presses it through a mold. This results in complex plastic parts such as toys, housings, or car parts.
- Additive manufacturing: Anyone who wants to produce precise, custom-made products also uses plastic granulate, especially in 3D printing.
The advantages and disadvantages of plastic pellets
The advantages
The versatile material is important to the plastics industry in several ways. It is not only easy to handle but also resistant and durable. Furthermore, the granulate can be processed into a wide variety of products and guarantees consistent product quality thanks to its standardized shape and production.
The disadvantages
Both the long durability and the high resistance of plastic are advantages and disadvantages at the same time. While the industry is pleased, the environment suffers. It usually takes hundreds to thousands of years for the material to decompose completely. Added to this are the CO2 emissions during the production of the granulate as well as the additives. Dyes, plasticizers, or reinforcers are a gain for the industry but a challenge for the environment. This makes it all the more important to recycle the granulate sustainably after use.