Technological breakthroughs

As the automotive industry faces major challenges from electrification (EVs), energy-efficiency regulations and sustainable development goals, tire structures are undergoing a material transformation. Within this context, para-aramid fiber has emerged as a key reinforcement material, redefining standards for strength, weight reduction and environmental performance.

1. Chemical nature and unique molecular structure

Para-aramid fiber, specifically poly-para-phenylene terephthalamide (PPTA), is a high-performance polymer fiber. Its defining characteristic is a fully para-crystalline molecular structure, in which polymer chains are highly aligned along the fiber axis during production.

This precise molecular orientation creates a tightly bonded network, allowing the material to achieve outstanding mechanical properties, including high thermal resistance, excellent cut resistance, chemical stability and, most notably, an exceptional strength-to-weight ratio. On an equal-weight basis, para-aramid fiber is approximately five times stronger than steel.

2. Closed-loop production process from monomers to filaments

The production of para-aramid fiber involves a complex sequence of chemical reactions and physical processing steps. The process begins with two monomers, terephthaloyl dichloride (TDC) and p-phenylenediamine (PPD), which react in specialized solvents such as N-methyl-2-pyrrolidone (NMP) and calcium chloride (CaCl₂) to form the PPTA polymer.

Following polymerization, the material undergoes coagulation, washing and drying. For fiber spinning, the PPTA polymer is dissolved in concentrated sulfuric acid (H₂SO₄) to form a spinning solution. This solution is extruded through microscopic spinnerets to create continuous filaments. The fibers are then washed, neutralized and heat-treated to stabilize the molecular structure before winding or further processing into chopped fiber or pulp.

3. Comparative analysis: why para-aramid is replacing traditional materials

Comparative performance data between para-aramid (e.g. Twaron 1000 series) and conventional tire reinforcement materials show clear technical advantages:

Breaking tenacity: Para-aramid reaches approximately 2044 mN/tex, compared with 805 mN/tex for polyamide 6.6, 726 mN/tex for high-modulus polyester (HMLS), and 447 mN/tex for steel.

Chord modulus: At around 73 GPa, para-aramid provides sufficient stiffness to maintain tire geometry at high speeds. While lower than steel (167 GPa), it offers a superior stiffness-to-weight balance.

Density: Para-aramid has a density of about 1440 kg/m³, less than one-fifth of steel’s density (approximately 7750 kg/m³).

Thermal shrinkage: At 180 °C, para-aramid exhibits near-zero shrinkage (around 0.1%), compared with 4.7% for polyamide 6.6 and 7.7% for polyester, ensuring dimensional stability under extreme operating conditions.

4. Strategic applications in modern tire architecture

Para-aramid fiber is engineered into different structural forms depending on its location and function within the tire.

Cap ply

In passenger car radial (PCR) and ultra-high-performance (UHP) tires, para-aramid is used as a cap ply to resist centrifugal growth at high speeds. This stabilizes the contact patch, improves handling precision and reduces irregular wear. It also mitigates flat-spotting after prolonged vehicle standstill.
Carcass and belt

In electric vehicles and heavy SUVs, high vehicle mass and instant torque place increased demands on tire structures. Replacing rayon or steel with para-aramid in carcass and belt layers allows a reduction in the number of reinforcement plies. This leads to a total tire weight reduction of approximately 6.1–7.5% and lower rolling resistance, contributing to extended EV driving range.

Other specialized applications

– Aircraft tires: Belt reinforcement for extreme durability and retreadability
– Racing tires: Weight optimization for improved handling and performance
– Off-the-road (OTR) tires: Enhanced corrosion resistance and durability
– Motorcycle and bicycle tires: Zero-degree belts for stability or anti-puncture layers beneath the tread

5. Economic and environmental assessment: the CBM model

Data from TÜV-certified Customer Benefit Model (CBM) analyses demonstrate both economic and environmental benefits. For a 275/45R19 108Y tire:
Replacing a rayon carcass layer with a single para-aramid layer saves approximately 1.1 g CO₂/km per vehicle, equivalent to 66 kg CO₂ over a 60,000 km tire lifetime.

Replacing a steel belt saves about 0.9 g CO₂/km, corresponding to 55 kg CO₂ over the same distance.

Reduced CO₂ emissions also help vehicle manufacturers avoid regulatory penalties, with estimated savings of 87–105 euros per vehicle, depending on the reinforcement configuration.

6. Toward a circular economy

The para-aramid fiber industry is increasingly adopting circular economy principles. Mechanical, physical and chemical recycling technologies are already in use to process industrial aramid waste. Recovered fibers can be converted back into raw materials and re-spun into high-quality filaments without compromising performance.

The current carbon footprint of para-aramid fiber is approximately 8.7 kg CO₂-equivalent per kilogram of product, which is low for a man-made fiber and supports the long-term objective of near-zero emissions across the automotive supply chain.

Conclusion

Para-aramid fiber technology represents more than a material substitution. It is a strategic enabler for lighter, stronger and more sustainable tires. By combining steel-like strength with textile-level weight efficiency, para-aramid fibers are playing a central role in shaping the future of tire engineering and global mobility.

Data presented in this article are synthesized from TÜV-certified test results and Customer Benefit Model calculations provided by Teijin Aramid as of February 2025. Actual performance values may vary depending on tire design and manufacturing conditions.

Source: Teijin Aramid. (2025). Tires today, tomorrow, together: Materializing ambitions (Mã tài liệu: 2400030). Xuất bản tháng 02/2025. Truy cập tại: www.teijinaramid.com/automotive