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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. 

 

Fiber Properties

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)