Plastic Refinement How Accelerated Electrons Optimize Plastics

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BGS Beta-Gamma-Service GmbH & Co. KG

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When mass-produced plastics reach their application limits, targeted property modification through radiation crosslinking can be a cost-effective alternative to high-performance plastics. Konstruktionspraxis spoke about this with the managing director of Beta-Gamma-Service, Dr. Andreas Ostrowicki.

BGS Offers Radiation Crosslinking of Plastics as a Service. What Advantages does this Process Bring?

The radiation crosslinking of plastics with high-energy electron or gamma radiation paves the way for applications that are often reserved for special or high-performance materials. Radiation crosslinking, for example, imparts inexpensive mass plastics and engineering plastics with the mechanical, thermal, and chemical properties of high-performance plastics. This "upgrading" enables their use under conditions that these plastics would otherwise not withstand. This is achieved without intervening in the production process: Radiation crosslinking takes place after shaping by injection molding, extrusion, or blow molding as the final processing step in the process chain on the way to the end customer. In particular, radiation crosslinking is characterized by high process reliability and reproducibility and saves plastics processing companies high investments, such as in new tools.

How does Plastic Refinement with Beta Radiation Work?

Radiation crosslinking relies on the effect of high-energy electron or beta rays, which are generated in electron accelerators. A key process parameter is the irradiation dose. The plastic is exposed to an exactly defined dose, thereby precisely controlling the crosslinking of the plastic molecules. This occurs throughout the entire component, meaning it is not merely a surface treatment technology.

During crosslinking, the material absorbs the radiation energy. Chemical bonds are broken, and free radicals are formed. Through recombination, the polymer chains crosslink with each other, forming an extremely resilient three-dimensional polymer network. Compact plastic components with high complexity and density sometimes require high penetration capability. For applications where the penetration depth of beta radiation is limited and no longer sufficient, crosslinking with gamma radiation is used. Gamma rays, as electromagnetic radiation, have significantly higher penetration capability.

In which Applications is Radiation Crosslinking Already Used?

Many industries and sectors have been utilizing the advantages of radiation crosslinking for years. These include, for example, plastics in cable and wire insulation, which require high heat resistance and chemical resistance, or pipes for heating and sanitary applications.

The applications of innovative plastic solutions are steadily increasing and are increasingly penetrating areas where metallic materials have previously been used. This is happening, for example, in all types of drives—gears, bearing bushes, or sliding elements are just a few examples where radiation crosslinking achieves improved wear resistance and higher mechanical load capacity, thus enabling a significant improvement in tribological properties. Another important application area is fields with increased requirements for temperature resistance, such as in the engine area or exhaust system, or in the area of electrical assemblies, where the radiation crosslinking of plastics completely changes the melting behavior and, for example, also brings significant improvements in the glow-wire test.

Can Radiation-crosslinked Plastic Semi-Finished Products be Further Processed without Losing the Property Improvements?

Plastic semi-finished products such as sheets, rods, tubes, and profiles are radiation crosslinked at the world's largest irradiation facility at BGS in Bruchsal. Not only do the resulting improvements in properties add value to a wide range of applications, but radiation crosslinking also leads to optimization in further processing through faster thermoforming and machining processes. The radiation-induced property improvements are not lost through the shaping further processing of the semi-finished products.

In the Future, You Also Want to Irradiate Fiber-Reinforced Plastics. What Will be Optimized in this Process?

It is already possible today to significantly improve the mechanical strength of fiber-reinforced plastics through radiation crosslinking, even at room temperature. The mechanical property improvements are mainly due to the better coupling of the reinforcing materials to the thermoplastic polymer matrix, caused, among other things, by the activation of the interfaces. Radiation-crosslinkable thermoplastic materials can be used, for example, in the RTM process as well as in injection molding, achieving short production cycles. Additionally, the improved heat resistance enables faster temperature-assisted 3D forming. This is a prerequisite for large-scale production of lightweight and high-strength structural components made of fiber-reinforced plastics.

Thank you, Dr. Ostrowicki.

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