Study On The Preparation And Properties Of Centrifugal Spinning Modified-melamine-formaldehyde Resin Fiber

Melamine formaldehyde?MF?resin is a kind of thermosetting resin with high nitrogen content,fire resistance and thermostability.It is made into different dimensions of materials which are widely used in the adsorption separation,flame retardant protection,battery separator and high temperature resistance filter,etc.For MF one-dimensional fiber material,people mostly use the form and characteristic of fiber to develop its potential applications,and the preparation and performance of MF microfiber itself are less researched.At present,the technologies of material fibrosis are mainly dry spinning,wet spinning,electrospinning and centrifugal spinning.Among them,the centrifugal spinning with high yield,simple device,easy operation,wide material applicability and low cost,as an emerging preparation method of micro/nano fiber material,has become a hot research topic in recent years.However,the poor storage stability and spinnability of MF resin limit its fibrosis and multifunctional applications.Hence,it is systemically studied that the preparation of modified MF resin solution,the forming process of centrifugal spinning fiber and the performance of melamine fiber in this paper.It can provide a scientific basis and reference for the rapid mass production and subsequent development of the versatilities of melamine microfiber.The improvement of the storage stability of MF solution starts from the synthesis stage of resin,including the selection of synthetic method,the adjustment of the reaction conditions and the selection of modifying agents.The synthesis method of MF resin is"two steps"in this paper.Triethanolamine as pH alkaline regulator replaces NaOH.There are five adding modifiers including polyvinyl alcohol?PVA?as basic modifier with physical and chemical modification functions,trimethylolpropane?TMP?and benzonquanmine as functional group closed modifiers,polyethylene glycol?PEG?and thiourea as flexible chain growth modifiers.It is investigated that the influence of the content of the mono-factor modifier on the stability of resin solution.Then,it is discussed that the effect of multifactor modifier combinations"PVA"?basic modified resin,comparison sample?,"PVA+PEG","PVA+TMP","PVA+thiourea"and"PVA+PEG+thiourea"on the stability of resin solution.Combined with visual inspection,turbidity test and viscosity measurement to test the storage stability of modified MF solution,it is found that the storage stability of MF solution is superior when the mass ratio of melamine and benzonquanmine is 80%/20%,mass fractions of PVA and thiourea are 4%and 2%,the modifier combinations are"PVA+PEG"and"PVA+PEG+thiourea".The optimal centrifugal spinning parameters are chosen to explore the spinnability of the different modified MF solution.two main variable parameters that are spinneret diameter and spinning speed are studied to investigate the spinnability of resin solution and"MF+PVA"is chosen to be an experimental centrifugal spinning solution.Considering the effect of spinning and the quality of fiber,the best spinneret diameter and spinning speed are respectively 27G and 3800rpm,the rest spinning parameters are that spinning viscosity is 2000 m Pa·s and the distance of collection is 12 cm.Then different modified MF solution is spinning in the optimal spinning parameters.Considering the storage stability of solution and combining the effect of spinning and the morphology of fiber,it can be concluded that the suitable mass ratio of melamine and benzonquanmine is 80%/20%and the optimal modifier combination is"PVA+PEG+thiourea".Therefore,it is expected that"benzonquanmine+PVA+PEG+thiourea"is the best modifier for MF resin.The test results show that the MF solution modified by"benzonquanmine+PVA+PEG+thiourea"is always transparent in 2h,the turbidity remains below 10NTU and the viscosity tends to be stable around 2000mPa·s.The effect of spinning and the morphology of MF microfiber whose diameter is about 4.5?m are both excellent.Melamine microfibers prepared by using the optimal modified solution in three spinning methods?centrifugal spinning,electrospinning and centrifugal electrostatic spinning?are compared for choosing the suitable spinning method in different fields in the future.The results demonstrate that the average diameter of fiber and the filling power of fiber assembly are from large to small to centrifugal spinning,centrifugal electrostatic spinning and electrospinning.The chemical structure,thermal property,surface relative element content and CO₂ adsorption capacity of MF fiber are measured by Fourier transform infrared spectroscopy?FTIR?,thermal gravimetric analyzer?TGA?,energy disperse spectroscopy?EDS?and specific surface area analyzer,separately.FTIR shows that the characteristic peaks of PVA,PEG and thiourea change because of setting off chemical reaction,and the characteristic peak of the benzene ring in benzonquanmine remains unchanged without occuring side effects.These indicate that the adding modifiers play a preconceived modification in the recation system.The TG and TGA curves show that the thermal performance of MF fiber don't decline rapidly after modification.The results measured by EDS shows that modifiers have small influences on the nitrogen content of fiber surface and the surface of fiber always maintains high nitrogen content.Finally,the CO₂ adsorption curves of the optimal modified MF fiber indicate that the amount of carbon dioxide adsorbed of fiber are only 0.11mmol/g and 0.06mmol/g at 0?and25?,respectively.It is far lower than the average level of the widely used products so that CO₂ adsorption performance of MF microfiber needs to be further improved.