Preparation And Properties Of Wet Spinning Of Phenolic Fibers

Phenolic fiber is a three-dimensional crosslinked organic flame retardant fiber prepared by spinning by the polymerization of phenol and aldehyde.Phenolic fiber has good flame retardancy,low smoke at high temperature,non-toxic,while the main products of phenolic fiber at high temperature carbonization are CO2 and H2 O,after carbonization,it still maintains the original morphology,large specific surface area,good adsorption and desorption.However,phenolic fiber has many problems in the application,its fiber forming difficulty is large,mechanical properties are poor,heat resistance is insufficient,and the resulting phenolic active carbon fiber has a high cost and is difficult to apply on a large scale.Therefore,it is necessary to modify phenolic fibers and study the spinning,carbonization and activation properties to improve the mechanical properties of phenolic fibers,improve the carbonization and activation process,and expand the application of phenolic fibers and their activated carbon fibers.In this experiment,boron(B)modified phenolic fibers with good performance were prepared by changing the proportion of raw materials in the process of synthesizing phenolic spinning stock solution,introducing boron modifier into phenolic.The prepared boron-modified phenolic fibers are carbonized and activated,and the boron-modified activated carbon fibers with the best performance are obtained by changing the conditions of carbonization and activation and the ratio of boron-modified phenolic fibers.1)By changing the content of polyvinyl alcohol(PVA)and boron modifier,the effect on the mechanical properties of boron-modified phenolic fiber was studied.The experimental results show that with the increase of PVA and boron modifier content,the elongation at break and breaking strength of fibers increase first and then decrease.Too low a PVA content is not conducive to the spinning of the fiber,but the more PVA content,the worse the stability,which will negatively affect the thermal properties of the fiber.Fibers with boron modifier content of 10% are more stable,with the highest residual carbon rate and the best heat resistance.When the PVA content is 5% and the boron modifier content is 10%,the boron-modified phenolic fiber has the best performance,the spinning viscosity of the spinning stock solution is 187.54 m Pa·s,the elongation at break is 8.02%,and the breaking strength is183 MPa.2)Boron-modified phenolic fibers prepared with a weight ratio of 5% PVA and 10%boron modifier were carbonized and activated.The effects of carbonization temperature,activation temperature and activation time on the adsorption performance of phenolic active carbon fibers were studied.The experimental results show that some pores will be formed after carbonization of the fiber,and the pores will increase after activation,and the adsorption capacity and adsorption speed will increase.When the carbonization temperature was 800℃,the activation temperature was 700℃ and the activation time was 1.5h,the residual carbon rate of boron-modified phenolic activated carbon fiber was 32%,the specific surface area was596.7m~2/g,the adsorption value of methylene blue was 492mg/g,and the adsorption value of iodine was 1772mg/g.3)The carbonization temperature was selected as 800℃,the activation temperature was700℃,and the activation time was 1.5h,and the effects of PVA and boron content on the properties of boron-modified phenolic active carbon fiber were studied.The experimental results show that with the increase of PVA content,the pores formed by the decomposition of PVA at high temperature increase,but the excessive pores also make the pore wall thin and disappear,and the carbon yield,specific surface area,and adsorption value of iodine and methylene blue of the fiber gradually decrease.With the increase of boron content,the carbon yield of fiber gradually decreased,and the specific surface area,adsorption value of iodine and methylene blue showed a trend of first increasing and then decreasing.When the PVA content was 5% and the boron content was 10%,the boron-modified phenolic activated carbon fiber had the best performance,the specific surface area was 596.7m~2/g,and the adsorption values of methylene blue and iodine were 492mg/g and 1772mg/g,respectively.