Structural Regulation And Properties Of Polylactic Acid Spunmelt Nonwovens

Faced with the large amount of waste from the use of plastics,disposable items and environmental pollution,people urgently need to find environmentally friendly materials that can replace petroleum-based polymers.PLA is a kind of biodegradable polymer and can be used as a substitute for petroleum-based polymers.At present,the non-woven field is dominated by PLA spunbonded hot rolled products,which have a smooth surface but feel stiff.At the same time,the research of PLA melt blown is still in the laboratory stage and it has not been industrial production.In order to improve the properties of PLA products and expand its application fields,combined with spunbonded and spunlaced technology,melt blown technology,the spunbonded spunlaced material and melt blown of PLA were prepared in this project.Moreover,Fluent was used to simulate the spunbonded and melt air injection flow field,and the experiment was guided according to the simulation results.It was divided into three parts in the paper:The first part was the simulation of spunbonded and molten jet flow field.In the spunbonded flow field,stable fiber draft point existed under the cooling wind speed of0.8 m/s,and the change of draft wind pressure did not affect the flow field distribution of the cooling blow.In the molten airflow field,the flow velocity and temperature fluctuated at 15-20 cm below the nozzle.The second part was the preparation of PLA spunbonded spunlaced nonwovens.The influence of draft wind pressure and spunlaced process on the properties of the product was studied.With the increase of draft wind pressure,the fiber crystallinity increases,and the longitudinal and longitudinal breaking strength and elongation of the product increase,the max longitudinal strength was up to 147 N/5cm and transverse strength up to 344 N/5cm.With the increase of spunlaced pressure and the number of spunlaced times,the transverse and longitudinal fracture strength of the product was significantly improved,the max longitudinal strength was up to 152 N/5cm and transverse strength up to 354 N/5cm.The softness of the product showed a trend of stiffening first and then softening.The influence of draft wind pressure on air permeability and moisture permeability of the product was much greater than the technological parameters of spunlace.The third part was the preparation of PLA melt-blown nonwovens.The influence of hot air pressure and distance from die to collector(DCD)were studied.The fiber diameter was decreased with the increase of hot air pressure,and the minimal diameter was 3.56?m.Meanwhile,the permeability of the product decreased and the filtration performance improved with the increase of hot air pressure.The air permeability and filtration properties of the product improved by increasing DCD and fiber diameter was around 3-4?m.The improved polylactic acid component material was achieved by melt electrostatic spinning,and the filtration efficiency was over 95%at 15 g/m~2,which showed the low quantitative and high filtration efficiency.