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Development of Flame-Retardant Polylactic Acid Formulations for Additive Manufacturing
Robert Aguirresarobe1, Itxaso Calafel1, Sara Villanueva2
1POLYMAT and Department of Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, Universidad del País Vasco/Euskal Herriko Unibertsitatea, UPV/EHU, 20018 San Sebastian, Spain.
Polymers
|April 27, 2024
Summary
This study explored 3D-printed poly(lactic acid) (PLA) with flame retardants for railway applications. Ammonium polyphosphate (APP) offered the best balance of fire resistance and mechanical properties, meeting EN 45545-2 standards.
Area of Science:
- Materials Science
- Polymer Chemistry
- Additive Manufacturing
Background:
- Polymeric materials offer lightweight, design-flexible solutions for railway vehicles, enhancing fuel efficiency and cost-effectiveness.
- Additive manufacturing (3D printing) enables tailored polymer compound formulations for expanded use in rail applications.
- Poly(lactic acid) (PLA), a biodegradable polymer, is investigated for its potential in railway components.
Purpose of the Study:
- To evaluate the printability and fire performance of poly(lactic acid) (PLA) compounds with halogen-free flame retardants (FRs).
- To assess formulations against the European railway standard EN 45545-2.
- To determine the optimal balance between fire resistance and mechanical properties for 3D-printed PLA in rail applications.
Main Methods:
- Formulation of poly(lactic acid) (PLA) with various halogen-free flame retardants (FRs), including ammonium polyphosphate (APP), expandable graphite (EG), and aluminum hydroxide (ATH).
- Assessment of printability and fire performance characteristics of the developed PLA compounds.
- Evaluation of polymer molecular weight and mechanical properties in relation to flame retardant additives.
Main Results:
- Condensed phase flame retardants like ammonium polyphosphate (APP), expandable graphite (EG), and intumescent systems demonstrated superior fire performance.
- Flame retardants inducing hydrolytic degradation (ATH, EG) reduced PLA's molecular weight, negatively impacting mechanical properties.
- PLA formulations utilizing ammonium polyphosphate (APP) as the flame retardant achieved the best compromise between fire resistance and mechanical integrity.
Conclusions:
- Optimized PLA compounds with specific flame retardants can meet stringent railway fire safety standards (EN 45545-2).
- Ammonium polyphosphate (APP) is identified as a highly effective flame retardant for 3D-printed PLA in railway applications.
- This research provides critical data for the rail industry to adopt advanced 3D-printed polymeric materials.
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