Evaluating the Potential of Polylactide Nonwovens as Bio-Based Media for Air Filtration

The presented research aims to characterize hydrolytic resistance of highly crystalline and oriented polylactide (PLA) as a prerequisite for exploiting this bio-based material in durable applications. Industrially melt-spun PLA monofilaments and nonwovens have been subjected to environmental aging in a temperature range of 50–70 °C at a wide range of relative humidity (RH) in order to identify the onset of the material degradation under application conditions. Along with the measurements of mechanical and thermal behavior of the aged samples, the suitability of FTIR spectroscopy to probe the initial changes in the crystalline structure and in chemical composition of the fibers, caused by hydrolytic degradation, has been evaluated. The diagrams of stability and hydrolytic degradation under employed environmental aging for 7–14 days are presented for both types of PLA materials. Assessment of filtration performance of the artificially aged fibrous PLA media indicated a good agreement with the established stability diagram and confirmed the application potential of PLA nonwoven media, spun from currently available PLA grades, in air filtration under moderate climatic conditions up to max 50 °C and 50% RH. The presented results advance the knowledge on hydrolytic resistance of bio-based industry-relevant fibers and therefore open new application areas for sustainable materials with biodegradable components.

Poly(lactic acid) fibers, yarns and fabrics: Manufacturing, properties and applications

Poly(lactic acid) (PLA) fiber was developed more than a decade ago. It has been regarded as the most promising sustainable and biodegradable fiber to replace conventional polyethylene terephthalate (PET) polyester fiber in textile products. This paper reviews recent developments in PLA polymerization, PLA filament and fiber spinning, staple yarn spinning, fabric production, dyeing and finishing and aftercare procedures. The properties of PLA fiber are broadly similar to those of PET fiber; however, the properties of PLA fiber that differ, including thermal degradation and low hydrolytic resistance to strong alkaline, significantly affect the method selection and parameter setting of production and processing of PLA fibers and fabrics. PLA filaments are mainly produced by two-step melt spinning to get fibers with stable quality, but degradation at high temperature is still a problem. PLA staple yarns are normally spun using ring spinning. Currently existing knitting or weaving techniques can be used to produce PLA fabrics. PLA fabrics can be dyed with disperse dyes at 110°C, but their color fastness and shades are different from PET fabrics when using the same dyes. The scouring and dyeing of PLA/cotton blended fabrics and the reductive clearing after dyeing remain to be improved. As a new fiber, the entry of PLA fiber into the textile market faces difficult challenges as well as great opportunities in the future.