Application of high-temperature and high-pressure processes in the flame-retardant finishing of polylactic acid nonwovens

This study examined the flame-retardant stability of polylactic acid (PLA) nonwovens after treatment with high-temperature and high-pressure finishing technology. Flame-retardant properties of PLA nonwovens were measured using a limiting oxygen index (LOI) and vertical combustion test. Surface morphology, elemental content, and thermal stability were measured by scanning electron microscope, energy dispersive spectroscopy, and thermogravimetric analysis. The LOI of the finished PLA nonwovens was 37.5%, which is 29.3% higher than that of the original nonwovens. The combustion length is reduced to 12.3 cm, the melting droplet phenomenon is significantly improved. After washing once, the LOI of the nonwovens decreased by 7.5%, and the vertical burning length increased by 13%. The finished PLA nonwovens have certain flame-retardant property. After finishing, the flame retardant was evenly distributed on the surface of PLA fiber, and the mass fraction of phosphorus reached 5.69%. Thus, the finished PLA showed improved flame-retardant property.