The Preparation And Properties Of Para-aramid/Polyphenylene Sulfide Composites By Wet Papermaking

With the development of science and technology,high performance paper-based materials have become the development direction and trend of special paper industry.The development of special paper with excellent mechanical properties is one of the hot topics in the field of special paper.The aramid paper-based material is generally prepared by aramid chopped fibers(ACFs)and fibrids fiber through modern wet paper process.They inherit a number of excellent properties of aramid fiber,and show good processability and redesign.There,it is widely used in rail transportation,electronics and electricity,aerospace,national defense and other high-tech fields.In addition,aramid paper-based materials also play an important role in the modern industry.Polyphenylene sulfide(PPS)has a very high bonding strength for aluminum,titanium,stainless steel,glass fiber and other metal materials.In the PPS ultrafine fiber prepared by melt-blown method,various fibers with different diameters form intersecting network structure.The obtained PPS ultrafine fiber has the advantages of small linear density,large specific surface area,excellent high temperature resistance and strong thermal stability.PPS bond aramid chopped fiber composite is a new type of structural composite fiber,which has excellent thermal stability,structural stability,water performance and dielectric properties.In this paper,the ACFs/PPS composites were prepared by wet paper making process and hot-pressing method,using para-aramid chopped fibers(ACFs)as the skeleton and PPS as the filler and binder.Specific research contents are as follows:(1)Preparation and properties of ACFs/PPS paper-based materials:in this paper,we combined the wet paper making and hot-rolling process to prepare ACFs/PPS composite paper-based materials.The influence of PPS content on the mechanical properties,microstructure and dielectric properties of the composite paper was investigated.Meanwhile,the thermal stability,water stability and folding resistance of the composite paper were investigated.The results showed that the best tensile strength,tensile strength and tear strength of ACFs/PPS composite paper were 97.1 N/cm,103.5MPa and 119.1 m N·m²·g^-1,respectively,when the content of ACFs was 70 wt%,the weight was 120 g/m²,the rolling speed was 0.2 M/min,the hot roll pressure was 0.2MPa,and the hot-pressing temperature was 310 ^oC.The isotropic mechanical properties of ACFs/PPS composite paper are excellent.The composite paper has good thermal properties and hydrophobic properties.After soaking in deionized water at 25 ^oC for 24h,the tensile strength of the composite paper only decreases by about 40%,which is better than most paper-based materials and has good water stability.ACFs/PPS composite paper has high breakdown strength,which is better than most polymer films.In addition,the dielectric constant is small due to a certain amount of porosity in the composite paper.(2)Recycling of waste ACFs/PPS composite paper:using waste ACFs/PPS composite paper,ANFs gel was prepared"from top to bottom"by combining beating and deprotonation method.In this paper,we characterize the relationship between the structure and properties of ANFs gel.The tensile properties and thermal stability of ANFs films were measured and characterized.FT-IR and SEM were used to characterize the structure and microstructure of ANFs,which showed that ANFs gel was successfully prepared.The tensile strength of ANFs membrane without any treatment after filtration and drying is about 20 MPa,which indicates that ANFs has excellent tensile properties.The transmittance of ANFs at 200-400 nm is about 5%,which indicates that ANFs gel,as a paper-based sizing agent,can effectively protect paper-based materials in extreme environments.(3)Preparation and application of ACFs reinforced PPS matrix composites:in this paper,we combined modern wet papermaking process and hot-pressing technology to prepare ACFs/PPS composites.The effects of different ACFs content on the mechanical properties,thermal stability,crystallization properties and dielectric properties of ACFs/PPS composites were systematically studied,and the fracture notch morphology was characterized.Mechanical performance test results show that ACFs/PPS composites tensile strength,elongation at break,bending strength,flexural modulus,interlaminar shear and impact strength to achieve the maximum values are 99.2 MPa,8.2%,181.4 MPa,13.1 GPa,8.8 MPa and 16.7 KJ/m²,respectively,when ACFs amount to 30 wt%,hot-pressing temperature is 310 ^oC,hot-pressing pressure is 30 MPa and hot-pressing time is 30 mins.Compared to the neat PPS,ACFs/PPS effectively enhanced the mechanical properties of composite materials and significantly enhanced the bending strength,which reaches to 181.4 MPa.Moreover,the TGA test results showed that the T_d10 of all composites exceeded 514.5 ^oC,which indicated the composites possessed high thermal stability.The obtained composites also showed low dielectric constant(3.3)and dielectric loss tangent(0.023)at 2 MHz.The study revealed that the dielectric constant of the composites exhibited weak frequency dependence from 50 k Hz to 2 MHz.The dielectric constant of the resin composite reinforced with one-dimensional material is also predicted using various theoretical models,and the results showed that the experimental value calculated using the Bruggeman equation was the one most consistent with the theoretical value.