Polylactic Acid Fibers
Properties
Polylactic acid (PLA) is an environmentally friendly, plant-derived thermoplastic. The fiber forming substance is a lactic acid polymer in which at least 85% by weight are lactic acid ester units derived from naturally occuring sugars (sugar beets and corn).
Although compostable, polylactic acid is quite durable in most applications. Infact, PLA does not readily degrade unless it is exposed to high humidity and elevated temperatures (≥ 60°C) which results in rapid decomposition of the fiber. Thus, for most applications, its durability is acceptable or good. The tensile strength of PLA fibers is comparable to those of polyester fibers. However, PLA has a low Tg of only 55 - 60°C and thus, is less heat resistant than polyester (PET). It is also more flammable and less abrasion resistant.
PLA is the only melt-processable natural based thermoplastic that can be melt spun into filaments which is often the most ecconomic and convenient method. However, the fiber can be also spun by a number of other methods. Dying can be accomplished with disperse or direct dyes using conventional processes when avoiding (strong) alkaline conditions.
| Tensile Strength (Tenacity) | Good1 |
| Chemical Resistance | Fair2 |
| Abrasion Resistance | Low |
| Absorbency | Low |
| Heat Resistance | Poor3 |
| Resistance to Sunlight | Excellent |
| Elastic Recovery | Good |
| Flammability/Smoke | Burns (Low smoke) |
| Resilience | Good |
1 Higher than
most natural fibers (can be comparable to PET)
2 Alkaline chemicals
cause rapid loss in strength.
3 PLA has a low Tg of
around 55 - 60°C
COMMERCIAL Polylactic Acid Fibers
Major manufacturers of polylactic acid fibers are Toray (Ecodear™), NatureWorks and MiniFibers.
Applications
PLA is fully biodgradable and biocompatible1,2 which makes this fiber attractive for medical applications like wound dressing. The fiber is also useful as an eco- and people-friendly alternative to existing textile fibers for industrial and consumer apparel applications such as outdoor furniture, automotive interior fabrics, activewear, shoe linings, and disposable products like diapers and wipes, either at 100% or in blends with natural fibers such as cotton.
1S.M. Davachi and B. Kaffashi, Polymer-Plastics Tech. & Eng., Vol. 54, 9, pp 944-967 (2015)
2G.D. Mogosanu and A.M. Grumezescu, Int. J. of Pharmaceutics, Vol. 463, 2, pp 127-136 (2014)