Abstract:

Objective Polylactic acid (PLA) micro-nanofibrous nonwovens have weak hydrophilicity and low cell adhesion, adversely affecting wound healing, and are more likely to cause inflammation when used for preparing dressings. This considerably limits the effective use of PLA micro-nanofibrous nonwovens in the healthcare sector. Therefore, it is necessary to modify PLA hydrophilicity to improve its use in healthcare applications.

Method Polyethylene glycol (PEG), sodium dodecyl sulfate (SDS) and polylactic acid are fused and blended. PLA blending raw materials with the SDS mass ratio of 0%, 0.3%, 0.6%, 0.9%, 1.2% and 1.5% are fed into screw extruder to melt. The melt is quantitatively transported to the spinneret hole of the die head by the pump and extruded in the form of melt stream through the spinneret hole. PLA micro-nanofibrous are formed by melt microflow under the action of high temperature and high-speed air flow at the die, which are then collected on the receiving screen after drafting and self-bonded to form PLA micro-nanofibrous nonwovens. Finally, the PLA micro-nanofibrous dressing is prepared by thermal lamination of the PLA micro-nanofibrous nonwoven and the viscose spunlaced nonwoven.

Results The contact angle of the sample free of SDS was 116° (>90°) and did not change with time. With the increase of SDS ratio, the wetting time of the sample was gradually shortened. When the SDS ratio reached 1.5%, the droplets could be completely spread on the material in 0.06 s, and the sample showed super hydrophilic effect at this time. The absorption intensities of infrared curves at 1 080 and 1 750 cm^-1 were enhanced after SDS addition, indicating that the ester group of PLA fiber increased after SDS addition, so the dynamic contact angle of the sample with SDS addition decreased at the same time, and the liquid conductivity of the sample was enhanced compared with that without SDS addition. The diffusion area of liquid on PLA micro-nanofibrous nonwovens increased from 36.05 cm² to 78.26 cm², which increased by 117.08%. The wetting time of the surface layer and bottom layer of the sample decreased from 5.34 and 3.75 s (3-5 s is fast) to 2.91 and 2.81 s (≤3 s is the maximum speed), respectively. The water absorption rate increased gradually from 4.38%/s and 4.31%/s (0-9%/s is extremely slow) to 9.15%/s and 9.39%/s (9%-29%/s is slow), respectively. The diffusion velocities of liquid water in the surface layer and bottom layer increased from 2.21 and 2.77 mm/s (2.0-2.9 mm/s is medium speed) to 8.34 and 8.11 mm/s (≥4.0 mm/s is the maximum speed). At this time, the liquid absorption rate reaches 429.94% and the liquid retention rate reaches 359.42%. According to the observation, the PLA micro-nanofibrous nonwoven with SDS has a significant influence in preparing wound dressing guide liquid, and can be naturally degraded after use, which is in line with the current characteristics of green environmental protection.

Conclusion PLA micro-nanofibrous nonwovens with rapid liquid conduction characteristics were prepared by melt blowing technology. A small amount of SDS can reduce the composite viscosity of PLA and make the polymer fluidity better. The rheological property of the polymer with SDS is better, causing the melt to be more easily drawn, so the diameter of the ejecta fiber is smaller. The addition of SDS will increase the ester group of PLA fiber, facilitating the rapid liquid conductivity enhancement of PLA micro-nanofibrous nonwovens. Moreover, the prepared PLA micro-nanofibrous dressings can be naturally degraded after use, which is in line with the characteristics of current green environmental protection, and has good research significance in the field of medical nursing.

Key words: nonwoven, melt blowing, micro-nanofibrous, polylactic acid, polyethylene glycol, sodium dodecyl sulfate, hydrophilic modification, dressing