Study On Preparation And Filtration Property Of PLA Nonwovens Via Meltblown/Electro-spinning

Poly (lactic acid) (PLA) is an excellent biodegradable material. Through nonwovens technology it is made into meltblowns (MB). Then through electro-spinning (ES) technology the electro-spinning fibers are spun onto the MB to produce PLA MB/ES bi-layer nonwovens (MB/ES Nws) and it is used for filtrations. Using ES technology instead of electret process, the PLA MB/ES Nws exhibits better filtration performance than MB in the same GSM and its filtration resistance remains unchanged. The produce process of PLA MB/ES Mws is simple and less energy costs during its producing, so the cost is low. It exhibits excellent particle separation performance during the air filtration process.Through adjusting the production parameters, such as hot air temperature, velocity, the width of air gap and die to collector distance (DCD), the relationship between the PLA MB technical parameters and its structure and performance is studied systemic in the paper. The results show that with the increase of hot air temperature, the filtration efficiency of the meltblowns decreases a little and air permeability increases. With the increase of the width of air gap, the filtration efficiency of the meltblowns decreases and air permeability increases. With the increase of DCD, the filtration efficiency and air permeability increases, and it changes linearly according to DCD. Because the interaction of the technical parameters, a three-layer back-propagation (BP) neural network model is further adopted to deal with the experimental data and forecast its performance. The results show that the average error of filtration efficiency forecasted is less than±3%, the average error of air permeability forecasted is less than±8%. It provides the academic foundation of optimizing the production parameters.On the base of successful preparation of PLA MB, it is mainly studied preparation technology of PLA MB/ES Nws in this papaer. The performance of ES fibers are better when the mixed solvent of 1,4- dioxane/acetone is adapted and the PLA quality concentration is 8% with a small quantity of NaCl in the spinning solution. After 10 minutes for electro-spinning, the integrated performance of filtration efficiency and air permeability of MB/ES PLA Nws is better. According to the prepared PLA MB/ES Nws, a structure model is further established and the relationship between the structure parameters and the process condition is also analyzed in this paper.Through adjusting the production parameters, such as voltage, extrude velocity and die to collector distance (DCD), the relationship between the electro-spinning technical parameters and its structure and performance is studied systemic in the paper. The results show that with the increase of voltage, the fiber diameter turns fine and the filtration efficiency of the PLA MB/ES Nws increases but air permeability decreases. With the increase of the extrude velocity, the average fiber diameter increases and the filtration efficiency of the PLA MB/ES Nws decreases first then increases, and its air permeability increases. With the increase of DCD, the fiber diameter turns fine and becomes uniform. As a result the filtration efficiency of the PLA MB/ES Nws increases and air permeability decreases. On the base of the structure model established before, a filtration model is further established to elaborate the filtration property of PLA MB/ES Nws in this paper. And the filtration parameters and different structure parameters which influenced the filtration property are analyzed in this paper.A three-layer BP neural network model with two-step training is adopted to deal with the experimental data and forecast the compound technical parameters of PLA MB/ES Nws. The results show that the average error of filtration efficiency forecasted is less than±0.5%, the average error of air permeability forecasted is less than±2%. It provides the foundation of producing high performance PLA MB/ES Nws filtration materials.