Experimental Research On Electrospinning Of Normal Electric Field And Pulsed Electric Field

Polylactic acid fiber is not only a green,environmental,ideal biological based chemical material,but also a polyester polymer material.It has highbiological properties,such as innocuity,biocompatibility,biodegradability and absorbability.And it has good mechanical properties,such as tensile strength,good resilience,ductility and thermal plasticity.Currently,polylactic acid fiber prepared by melt electrospinning is a cheap,popular and easy to industrialization method,which has become the mainstream of polylactic acid fiber production.In this paper,a series of experiments on the preparation of polylactic acid fibers by melt electrospinning are done by controlling the single process variables.The melt electrospinning machine of this study is developed by our laboratory.The fibers prepared by the basic experiments are used as the reference groups for the follow-up experiments.The results of the study showed that the thermal processing temperature of the granular poly(L-lactic acid)was at 190?230 ?.The effect of voltage and distance on fiber average diameter is relatively large,but the law is not obvious;and the effect of current on fiber average diameter is relatively small.In this paper,the range of the high voltage power supply is 30?45 kV,the range of heating temperature is 220?250 ?,and the spinning distance is between 6.5 cm and 9.5 cm.The finest and most uniform fibers are produced at the spinning distance of 7.5 cm,the heating temperature of 250 ?,and the high voltage power supply of 35kV.The average diameter of the fiber prepared under this condition is 2.658±1.632 ?m.In addition to measuring the diameter of these experimental products,the study also tested the crystallization of these experimental products.Keep other conditions unchanged,the tablet before receiving experiment replaced static 8 mm diameter cylindrical and high-pressure needle receiving,preparation of refinement of PLLA fiber,and also studied the effect of process parameters on fiber,focusing on the influence of temperature on fiber diameter.Keeping other experimental conditions unchanged,the previous reference group's flat reception was replaced by a stationary 8mm diameter cylinder and needle receiving.The refined polylactic acid fiber was prepared,and the effect of process parameters on fiber was also studied.The effect of temperature on fiber diameter is emphatically studied.The experimental results show that,through the comparison of 11 groups of experiments,the reduction of the receiving board can make the fiber aggregate and make the average diameter of the fiber smaller.In the 39 groups of experimental results,the experimental conditions were 2.658± 1.632 ?m for the finest fibers under the conditions of 250 ?,30 kV and 7.5 cm.According to the research results,the following rule is obtained:between 6.5 cm and 8.5 cm,the longer the spinning distance,the finer the fiber.Between 30 kV?45 kV,the higher voltage power,the finer the fiber,but the effect of temperature on the diameter of the fiber is not obvious.The main principle of fused deposition modeling is that the thermoplastic material is extruded and expanded from the nozzle through heating,and two times of melt deposition is achieved through air cooling.In recent years,this processing method is very hot in the domestic and foreign research.In principle,it is similar to the melt electrospinning.Therefore,we independently built a new melt spinning device combined with 3D printing pen and DC high-voltage power supply and replaced the receiving plate with the mobile high-pressure needle.Based on the principle of near-field electrospinning,the effect of fiber process parameters and crystallinity on fiber diameter was studied by using the same method as before experiments.The material used is filamentous poly lactic acid,and no high-voltage power supply is used as an experimental control group.The results show that the electrospinning conditions of the fiber with the average smallest diameter are at 180 ?working temperature,the high voltage of 45 kV and the distance of 6mm.Under this condition,the average diameter of the optimum fiber is 0.5171±0.0249 mm.By using this condition,four different patterns were accurately printed,which proved that the refinement of the high voltage electricity still existed in the molten deposition.This shows that the addition of a high voltage power supply can be used as a simple,low cost method to improve the fiber thickness of 3D printing to the actual situation.Finally,the principle of near-field electrospinning is used to obtain the finer and directly written fiber diameter of 4.64±0.73 ?m at the temperature of 230 ?,the high voltage of 15 kV and the distance of 4mm by using the former melt electrospinning device.And the patterned fiber was prepared.In order to further study the ordering of fibers with biological properties,the fibers membrane of PLLA/PEO/nHA mixed system with different proportions was prepared by the melt electrospinning with high speed roll receiving.This fiber membrane has good biodegradability,no solvent toxicity and is arranged neatly.