Thinking Thermoplastics

Hayley Everett

What distinct advantages can new thermoplastic materials bring to the rail sector?

The transport sector’s design and manufacturing processes have long been trending towards requirements for greater fuel efficiency, providing a luxurious riding experience, and enhanced safety. As more mass equals more fuel consumption, utilising materials that reduce the overall weight of passenger buses, trains and aircraft will, in turn, lead to decreased energy consumption, less brake and tyre wear, and lowered emissions.

Thermoplastics offer the transport sector focused material options that are simultaneously rigid, durable and lightweight, alongside a manufacturing process that enhances design capability, lead time, and the look and feel of components. The rail industry, in particular, is harnessing these advantages by leveraging thermoplastics for interior applications such as wall and ceiling panels in passenger trains, subways and trams.

New Thermoplastics

One such example is the recently launched range of LNP Elcres FST copolymers from chemical specialist Sabic, which are designed specifically for rail interior wall panels. Fully compliant with the European railway standard for fire safety, the new speciality thermoplastic meets the key requirements of rail OEMs in regard to durability and custom colourability. Specifically, the material offers high modulus for durability, moulded-in custom colour for paint elimination and branding, ultraviolet (UV) resistance to help minimise yellowing, and chemical resistance to facilitate cleaning removal without causing environmental stress cracking.

According to Sabic, LNP Elcres FST provides distinct advantages over stamped metal and thermoset resin alternatives, such as expanded design freedom and system cost reduction. Additional benefits include 20% less weight for easier maintenance as well as the potential for easier recyclability.

“As travel rebounds, the rail industry is looking for ways to increase the number of passengers – and one promising approach is to upgrade the interior of the train to deliver a more satisfying customer experience and improve sustainability,” says Joshua Chiaw, Director Business Management, Specialities at Sabic.

Increasing Sustainability

With the aim of increasing the sustainability of rail interiors, Sabic also supplies the new copolymer in a bio-based version with the same regulatory compliance, performance properties and processing parameters as the fossil-based grade. Formulated with around 55% renewable feedstock from waste materials such as crude tall oil, the bio-based material was found to reduce carbon emissions by approximately 28% when compared to fossil-based counterparts, according to an Intergovernmental Panel on Climate Change (IPCC) CO2 equivalent analysis.

“We are addressing passenger rail trends by expanding our portfolio of speciality materials to help meet the latest requirements,” Chiaw continues. “By developing new grades that comply with stricter regulations, offer system cost advantages, and enhance aesthetics, durability and sustainability, we aim to support industry efforts to maximise the appeal of rail travel as a cost-effective, safe, reliable and convenient choice.”

Fire Safety Compliance

Both the fossil-based and bio-based LNP Elcres FST thermoplastic grades meet the strict fire safety requirements of EN 45545 R1-HL2 for horizontal and vertical interior surfaces, including ceilings and walls. These regulations, which are considered the global benchmark, aim to minimise the effects of heat, smoke and toxic gases on rail passengers and staff, and Sabic’s new materials are among the few colourable thermoplastics that are compliant.

The thermoplastic copolymers are developed for extrusion-based manufacturing processes and produce sheets that can be thermoformed to suit panel thicknesses of between 2-5mm.

Design Advantages

When compared to metal and thermoset resins, Sabic’s new thermoplastic materials provide greater freedom in the design of new panel configurations, enabling the integration of aesthetics, parts and functionality without the need for secondary processes. For instance, a decorative film can be applied to LNP Elcres FST thermoplastic panels during extrusion, whereas a thermoset part would require a separate application step. Additionally, brackets and fasteners can be integrated using laser welding instead of requiring adhesives.

Another design advantage of the new copolymer range is its moulded-in colour capability, which eliminates the cost, time and emissions of volatile organic compounds (VOCs) associated with painting, which is typically used for metal and thermoset panels. Meanwhile, the materials’ excellent chemical resistance makes it easy to clean, which in turn helps to extend the useful life of the part.

“Our LNP FST products for rail panels demonstrate the success of Sabic’s technical experts in solving major challenges around compliance, quality, durability, cost control and sustainability,” adds Luc Govaerts, Technology Director, Specialties, at Sabic. “In developing these new grades, we worked closely with customers to understand their needs and preferences, including requests for bio-based, drop-in alternatives that strengthen environmental protection. These speciality copolymers represent a new generation of materials for panels and open up new possibilities for the industry.”