A Study On PE/PP Fibers Prepared By Melt Electrospinning

Solution electrospinning has now become a research focus in academia. However, in order to get rid of the solvent, cleaning processing, environmental safety, and productivity become new problems in the present research. So there is a persistent desire to explore a new method to prepare ultrafine fibers effectively while it has no affects on the health of human being and environment. Melt electrospinning has the same primary theory as that of soltion electrospinning in making ultrafine fibers while lacks of solvent. Whether melt electrospinning can be used to prepare ultrafine fibers by controlling the parameters? It is the purpose of this paper. In this paper, fibers of polypropylene (PP), polyethylene (PE) and their blends are prepared by melt electrospinning. The process of the electrospinning is analyzed in detail. Scan electron microscopy (SEM), polarizing optical microscopy (POM), phase differential microscopy (PDM), differential scanning calorimetry (DSC) are used to characterize the diameters and morphology of the electrospun fibers. The effects of various melt-electrospinning parameters, including melt flow index (MFI), voltage, capillary-collection plate distance, melt temperature, collection speed and PP content, on the morphology and fiber diameter of PP as well as the compatibility of PE and PP are discussed. The results show that PP fibers with the sizes of 0.4~100 μm in diameter are successfully prepared by melt electrospinning. The parameters have the same effect on the morphology and diameter of the electrospun fibers as do in solution electrospinning. For the melt electrospinning of the PP and PE, the increase of the collection speed is in favor of the decrease of the fibers diameters and the surface morphology of the fibers, but too much collection speed can result in the conglutination of the fibers. Fibers diameters increase with the increase of the volume rate. The concentrations of PP and PE for melt electrospinning are 30 % and 40 % respectively. For the melt electrospinning of their blends, the fibers diameters increase with the increase of PP content, the distribution of the fibers diameter turns from narrow to broad firstly, then turns from broad to narrow. Similarly, the surface morphology of the fibers turns from smooth to coarse firstly, then turns from coarse to smooth. The increase of the collection speed and voltage can result in the decrease of the average fiber diameter, the orientation of the polymer molecules, the degree of the compatibility of PE and PP, but with the increase of the PP content, the fibers are inclined to conglutinate to each other; When the PP content is lower than 20 %, it acts as the plasticizer to PE, whereas, when the PP mass rate is higher than 70 %, it will be plasticized by PE. When PP content is as much as PE content, there can appear two continuous phases, as a result, the mechanical properties of the PE/PP electrospun fibers are weakened.