| In this paper,the influence of the airbag on the damping performance of the hollow fiber damping material was discussed with NBR as the basic material.The airbag includes the inner core tubular cavity and the pores in the membrane,the influence of inner core size,pore structure and porosity on the damping property of the material is discussed in this paper.And the differences of results under different clamping modes of DMA are also studied;the pore structure and porosity of the hollow fiber membrane were also changed by changing the concentration of the casting solution,the composition of the core solution and adding additives,study the influence of different membrane pore structure and porosity on the damping properties of hollow fiber damping materials.About the NBR anti-stick anti-flat blending modified formula,the subject group has done a related study,this paper selects the appropriate solid content and blending ratio directly,to explore the hollow balloon damping damping properties of hollow fiber.During the experiment,it was found that diameter of the hollow fibers was affected by many factors(such as speed,velocity and inner core flow),different sizes spinning heads need to adjust the corresponding spinning parameters to achieve the purpose of spinning hollow fiber size control.In this paper,fluorescence microscope was used to measure the inner and outer diameter of the hollow fiber membrane,and the spinning parameters of different spinning heads were determined;Through comparison and analysis,the following conclusions are obtained:(1)The size of the hollow fiber depends not only on the size of the spinning head but also on the spinning parameters.When the spinning head size is fixed,increasing the inner core flow rate will increase the inner diameter,and increase the extrusion speed,so that the film thickness can be increased appropriately.(2)Under the natural support of hollow fiber membrane,the bigger the inner diameter,the better the damping performance of the material.And the cutting,stretching,single cantilever fixture test mode of DMA all follow this rule.It shows that the airbag structure of the material damping performance has a certain contribution.(3)Test the damping performance of same sample with three different loading modes of DMA,it is found that the damping peak exhibits the shear clamp damping is the best,followed by tensile clamp damping,and finally single cantilever beam clamp damping;And the glass transition temperature moves in the direction of low temperature successively,It shows that the damping property of hollow fiber damping material under different loading modes is different,that is to say,its hollow air bag damping is anisotropic.(4)In the experimental conditions,the concentration of casting liquid was changed.With the increase of casting solution concentration,the pore structure was inhibited and the porosity decreased.When the casting solution concentration was 18%,the damping performance of hollow fiber was the best.Porosity makes the material damping performance better,but the pore volume should be moderate,too large single hole volume will affect the mechanical strength of the material and affect the damping performance.(5)In the experimental conditions,the composition of the inner core and the mixing ratio were changed.With the increase of the ethanol content in the inner core,the growth of the medial finger hole was inhibited and the sponge pore structure was thickened.When the volume fraction of ethanol / water solution is 30%,the damping capacity of the material is the best;The inner pore is the bridge connecting the tubular cavity and the inner pore,When the inner layer is a denser hole,it is beneficial to the damping property of the material,but avoiding porosity is too low to influence the whole damping property of the membrane.(6)Under the experimental conditions,adding different amount of polyvinyl pyrrolidone(PVP),when PVP content is 2%,the damping performance is the best;after adding PVP,the supporting layer of the membrane develops into large pore structure,the spongy pores are more compact and compact than those without PVP,and this structure also makes the material damping property better.(7)Under the experimental conditions,the different content of phosphoric acid was added,and with the increase of phosphoric acid content,the cavernous pores in the membrane were more porous;Compared with the hollow fiber without phosphoric acid,the porosity increases by 2 percentage points,and the damping loss factor increases by about 0.01,the damping performance is enhanced.(8)In the experimental condition,the polyethylene glycol(PEG)with different molecular weight was added,with the increase of PEG molecular weight,the cortical pointed hole was developed in the middle and the porosity increased.When adding PEG6000,the damping performance of hollow fiber increases greatly.PEG addition should be appropriate,too many PEG can suppress the development of the pore structure,thus affecting the damping property of hollow fiber. |
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