Melt-blown process of low-density polyethylene and its nonwovens properties
Objective Polyethylene(PE)nonwovens have excellent characteristics such as softness,corrosion resistance and hydrophobicity,and have broad application prospects in medical packaging,clothing,filtration and other fields.However,the traditional preparation process of high-performance polyethylene nonwovens is cumbersome,and the production process involves a large number of toxic solvents,and the production efficiency is low.Exploring the efficient preparation process of ultrafine polyethylene nonwovens has become an urgent research problem to be solved.Melt-blown technology is a common and efficient preparation method for microfiber,and the preparation of polyethylene microfiber by melt-blown method is rarely reported.Method The preparation of low-density polyethylene(LDPE)melt-blown nonwovens was achieved by using a self-assembled melt-blown testing machine.The effects of different processes on the diameter of LDPE fibers were studied by controlling a single variable and adjusting the melt-blown process parameters in the experiment,including hot air temperature,hot air flow,mold temperature,melt flow and receiving distance.In addition,the filtration efficiency and tensile properties of LDPE melt-blown nonwovens were also studied.Results The effects of melt-blown process parameters on the diameter of LDPE fibers were studied,including different hot air temperature,hot air flow rate,die temperature,receiving distance and melt flow rate.The results showed that increasing the hot air temperature,hot air flow rate and die temperature would reduce the average diameter of the fiber,and the average diameter of the fiber would increase after increasing the receiving distanc and melt flow rate.The minimum average diameter of the prepared fibers reached 5.3 μm,offering reference value for further preparation of polyethylene microfibers.The filtration performance of LDPE melt-blown nonwovens with different areal densities was explored,and the effect of areal density on LDPE filtration efficiency and filtration resistance was established,with the increase of areal density,the filtration efficiency and filtration resistance of melt-blown nonwovens showed a gradual upward trend.The filtration resistance was increased from 5.1 Pa to 20.9 Pa,and the filtration efficiency increased from 52.89％to 59.32％.After hot pressing treatment,the filtration efficiency of the 120 g/m2 nonwoven fabric reached more than 75％at a flow rate of 32 L/min,and the average filtration resistance is 80 Pa.The mechanical properties of LDPE melt-blown nonwovens with areal densities of 25 g/m2,50 g/m2 and 120 g/m2 were investigated.The nonwovens with higher areal density were found to withstand greater tensile strength,and when the areal density is 25 g/m2,the LDPE melt-blown nonwovens demonstrated the highest elongation at break,up to 75％.When the areal density was 120 g/m2,the maximum pulling force and tensile strength of melt-blown nonwovens were the highest,reaching 6.12 N and 2.16 MPa,respectively.Conclusion The melt-blown process can realize the efficient preparation of LDPE nonwovens,and the average diameter of the fiber decreases with the increase in hot air temperature,hot air flow rate and die temperature,and increases with the increase of receiving distance and melt flow,and the filtration efficiency,filtration resistance and tensile strength of melt-blown membrane increase with the increase of surface density of nonwoven.Process parameters would affect the microstructure and pore morphology of the fiber membrane,resulting in changes in mechanical properties and filtration properties.Furthermore,the microstructure of the melt-blown nonwoven can be changed by post-treatment processes such as hot pressing,and products with better performance can be obtained.So as to enhance the market potential and application value of polyethylene melt-blown nonwovens in the field of medical protection.
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