Melt electrospinning is a cheaper, more environmentally friendly, and safer alternative to solution electrospinning. We have designed a novel melt spinning device which incorporates a reverse of the normal polarity, with the capillary grounded and the collector grid at positive potential. The apparatus is much simpler and more economical than conventional equipment because no syringe pump is required. Low-density polyethylene (LDPE) with a low-melt flow index of 2 g/10 min, which is not suitable for spinning using current commercial methods, was chosen to highlight the advantages of melt electrospinning in general, and our device in particular. The effects of varying the electrospinning parameters such as temperature, electrostatic field, spinning distance, and capillary inner diameter, have been studied. Although it was found that temperatures higher than normal processing temperatures had to be employed in our electrospinning system to reduce the viscosity of the polymer melt sufficiently, good quality fibers with smooth and even surfaces, most of which had diameters smaller than 15 lm, were electrospun successfully. It was observed that there was an optimum point for the spinning distance (14-15 cm) and the capillary inner diameter (0.4-0.6 mm) to get fine fiber.

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Fused deposition molding (FDM) is the most popular technology in the fields of three‐dimensional printing, but it is hard to use a variety of plastic materials due to the limitation of filament form of material. Using plastic pellets as printing materials gives advantages in cost, processing speed, and available materials. In this work, a large‐scale double‐screw FDM three‐dimensional printer based on plastic pellets has been designed. It is capable of printing large plastic products at a low cost and high speed. Using ABS + 10%GF as printing material, this work is first focused on the effects of the pressure and speed of the metering screw on the flowrate of melt. The equation for the relationship of these three parameters was established as well. Based on this equation, the effects of melt flow, printing speed, and layer thickness on the width of fused filament were investigated with experiments. Furthermore, the effects of printing spacing between fused filaments on surface accuracy and bonding strength were also explored. By printing models, it was revealed that the designed printer is able to print products with plastic pellets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45147.

Ultrafine polypropylene (PP) fibers as oil sorbents were fabricated via a needleless melt-electrospinning device and were characterized by scanning electron microscopy and contact-angle analysis. PP fibers of various diameters and porosities were obtained by the manipulation of the applied electrical field. The effects of the fiber diameter and porosity on the oil-sorption capacity and oilretention behavior were investigated. The experimental results demonstrate that for fiber diameter on the microscale, the porosity played a paramount role in determining the oil-sorption capacities. The maximum oil-sorption capacity of the resulting PP fibers with regard to motor oil and peanut oil were 129 and 80 g/g, respectively; these values were approximately six to seven times that of commercial PP nonwoven fabricated through the melt-blown method. In addition, even after seven sorption/desorption cycles, the oil-sorption capacity of the chosen sample was still maintained around 80 g/g, and above 97%, oil could be recovered. This indicated excellent reusability and recoverability.

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