| With the applications of nanofibers involved in various important industries,so the market demands for the preparation method and the process conditions of nanofibers also become higher.In nearly a decade of rapid development,the new centrifugal electrospinning technology combines centrifugal spinning with electrospinning.It is not only a combination of the advantages of two methods,but also the combination of two kinds of complex devices.So this preparation method for nanofiber industry is both an opportunity and a challenge.Centrifugal electrospinning can use raw materials with different states.Centrifugal melt electrospinning use melt as raw materials and centrifugal solution electrospinning use solution as raw materials.Up to now,the fibers fabricated by centrifugal solution electrospinning are inevitable with the side effects of solvent,and centrifugal melt electrospinning have not been studied by researchers in detail.Because there are a lot of difficulties in the traditional melt spinning method,including the influence mechanism of different temperature and different heating time for different materials is not clear,and equipment is difficult to accurately control temperature.For specific melt electrospinning preparation,fibers diameter are coarser,fibers are disorderly,and the low efficiency.Fibers overall performance fabricated by centrifugal melt method is not unified.All these cannot meet the application criteria.These are hindering the spinning along the way of industrialization.To overcome the disadvantages of the existing spinning method,to cater to the development trend of nanofibers,our lab targeted begin to explore experiments and simulation of centrifugal melt electrospinning.The following is the main research content:First of all,using the lab independently design and manufacture of centrifugal melt electrospinning device to explore whether this set of centrifugal melt electrospinning device can smoothly prepare nanofibers only using solid-state Poly-L-lactic acid materials and analyzes its security and maneuverability.At the same time,the properties of Poly-L-lactic acid nanofibers prepared by this device are characterized,and summarize the detailed process parameters.The results show that this device can be smooth and efficient preparation of solvent-free Poly-L-lactic acid micro/nanofibers membrane,and summarize the detailed regulars of voltage,speed,temperature and other process conditions effecting on fiber diameter,yield and crystallinity.And the optimum range of the conditions of this device in the preparation of Poly-L-lactic acid is in commonly:voltage is 35 kV,rotational speed is 1260 rpm,temperature is 235 ℃ and collecting distance is 8 cm.Secondly,further using centrifugal melt electrospinning technology prepare orderly PLLA nanofiber membrane,and characterize the degree of orderly of fiber membrane,and summarize the regular of voltage,rotational speed,temperature effecting on fibers’ degree of order.And then we explore the medical applications of the orderly fiber membrane and disordered fiber membrane,including Live/Dead,proliferation and differentiation of cells.In the end,we successfully prepared highly ordered Poly-L-lactic acid micro/nanofiber membrane,and disordered fiber membrane,and summarize the regular of different process parameters effecting on fiber’s degree of orderly.Biomedical experiment results show that this kind of solvent-free Poly-L-lactic acid fiber membrane is non-toxic,cell survival rate is more than 95%,and cells proliferation and differentiation on the orderly fiber membrane stent is better than disordered fiber membrane.So these prove that this method of preparation of solvent-free Poly-L-lactic acid fiber membrane can imitate the inherent tendon in the form of organizational structure,and has huge potential in the concrete of tendon injury and disease related regeneration medical applications.Then,this paper begins to explore the centrifugal melt electrospinning method to prepare compound fiber membranes containing of Poly-L-lactic acid and Polyethylene oxide,aiming to improve the mechanical properties of Poly-L-lactic acid fiber membrane.And the performance of the composite fiber membrane is characterized and fiber membrane is taken mechanical performance test.By compared with pure Poly-L-lactic acid fiber performance,the diameters and crystallinity of compound fiber membrane are obviously improved.The finest average diameter of composite fiber membrane is 1.85 um.And along with the PEO content increasing in the composite fiber membrane from 10%to 30%,the crystallinity of composite fiber membrane obviously promoted.After subsequent processing of hot pressing,the strength of the composite fiber membrane has also been improved.But the toughness of membranes still needs to be explored.All these show that this device can prepare high-performance composite fiber membrane.Further validated this device can potentially reach the level of industrial application.Although we successfully prepare solvent-free nanofiber membrane using the centrifugal melt electrospinning device,we also encountered many difficulties and problems,especially the complicated mix of device and testing accuracy of various kinds of device parts;these have a great influence on spinning experiment.In order to continuously improve equipment,faster and more efficient to obtain new design of device to the influence regular of spinning fiber,the temperature simulation of the rotational cylinder in centrifugal melt electrospinning device is conducted for judging the temperature measurement precision.According to the simulation situation,we try to design a new generation of centrifugal melt electrospinning equipment,and wrote patent related equipment.Then we try to simulate the temperature field of the rotational cylinder of new device by ANSYS software.Results show that the new structure device has the advantage of more accurate temperature measurement and more uniform temperature distribution.And these work out the critical temperature problem in melt spinning. |
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