Study On Preparation And Properties Of Para-aramid/Polyphenylene Sulfide Filter Material

Particulate matter（PM）air pollution has become a major environmental concern due to accelerating industrialization and urbanization in developing countries.According to the Institute for Health Metrics and Evaluation,air pollution affects human health.Long-term exposure to PM_2.5 pollution can cause serious health problems such as respiratory disease,cardiovascular disease,heart disease,and lung cancer.PM is typically produced by high temperature（>200°C）processes such as coal combustion,municipal solid waste incineration,and industrial pollution emissions.Therefore,effective control of high-temperature industrial dust is of great significance to environmental protection and human health.The existing high-temperature dust removal technology is mainly bag dust collector,and the dust filter bag is the core component that determines the performance of bag dust collector.Polyphenylene sulfide（PPS）fiber is one of the most widely used fiber filter media due to its excellent thermal stability and corrosion resistance.However,PPS fiber is prone to thermal cross-linking at high temperature,which leads to a significant decline in its mechanical properties.Relative to the PPS,PPTA fiber owns better thermal stability.PPTA fiber is also applied in the filter materials.It is very interesting to develop the PPTA filter with good thermal stability,higher filter performence,and low surface density.In view of this case,this paper carried out the following three aspects of research:In view of the above problems,this paper carried out the following three aspects of research:（1）Para-aramid short-cut fiber（PPTA）was combined into PPS ultrafine fiber by wet dissociation and dry thermal consolidation technology to construct a ultrafine fiber composite felt with PPTA as the skeleton and PPS ultrafine fiber as the binder.By virtue of the strong interfacial bonding force between microfused PPS fiber and PPTA fiber,the composite felt has excellent structural stability,and the introduction of PPTA fiber can further improve the thermal stability of composite felt.The test results show that:When the PPTA content of the filter felt is 70%,the thermal consolidation process is270°C,the pressure is 30 MPa,and the time is 10 min,The filtration efficiency of PPS/PPTA ultrafine fiber felt for PM_0.3,PM_0.5,PM_1.0,PM_2.5,PM_5.0,and PM₁₀ was89.02%,97.34%,99.85%,99.99%,100%and 100%,respectively,and the filtration resistance was 510 Pa.The quality factor of PM_2.5 was 0.0127.In addition,the PM_2.5filtration efficiency of PPS/PPTA ultrafine fiber felt can still be maintained above 99.73%after being placed at 230°C for 48 hours or immersed in strong acid-base solution for48 hours,showing excellent thermal and chemical stability.In addition,PPS/PPTA felt also had good structural stability.The tensile strength and tear index reached 32.93N/cm and 22.77 m N·m²/g,respectively.（2）PPS ultrafine fiber/PPTA fiber felt has excellent filtration,mechanical and thermal stability properties,but its filtration resistance is relatively high,which affects the practical application.In this paper,on the basis of the prepared PPS/PPTA ultrafine fiber felt,by introducing aramid pulp fiber（AP）,combined with high-temperature and rapid heat treatment process,the pore size of composite fiber felt was adjusted to reduce the filtration resistance of fiber felt.The test results show that:When the ratio of PPTA,AP and PPS is 6:1:3,and the heat treatment temperature is 300℃and the heat treatment time is 3 min,the comprehensive performance of PPTA/AP/PPS composite fiber felt is the best.The filtration efficiency of PM_0.3,PM_0.5,PM_1.0,PM_2.5,PM_5.0 and PM₁₀ was65.63%,83.81%,98.73%,99.99%,100%and 100%,respectively.The filtration resistance was 85 Pa,and the quality factor of PM_2.5 was 0.1079.The tensile strength was 37.56 MPa.The TGA test results showed that the T_d10%of the composites all exceeded 510°C,indicating that the composites had high thermal stability.After 24hours of 1 mol/L hydrochloric acid or sodium hydroxide acid-base corrosion,the PM_2.5filtration performance remained above 99.99%.It shows that the material has excellent acid and alkali corrosion resistance.（3）Cellulose fiber（CF）has the advantages of wide source and low cost.In the third chapter of this thesis,the PPTA/CFs/PPS composite fiber felt was prepared by using wet dissociation and dry thermal consolidation technology and high-temperature heat treatment technology.The PPTA/CFs/PPS composite fiber felt had excellent filtration efficiency,mechanical strength and high-temperature resistance,and further reduced the preparation cost.The results showed that:When the ratio of PPTA,CFs and PPS is6:1:3,and the heat treatment temperature is 300℃and the heat treatment time is 3 min,the comprehensive performance of PPTA/CFs/PPS composite fiber felt is the best.The filtration efficiency of PM_0.3,PM_0.5,PM_1.0,PM_2.5,PM_5.0 and PM₁₀ was 59.14%,82.14%,98.44%,99.99%,100%and 100%,respectively.The filtration resistance was 48 Pa,and the quality factor of PM_2.5 was 0.0864.The tensile strength was 30.67 MPa.The TGA test results showed that the T_d10%of the composites all exceeded 496°C,indicating that the composites had high thermal stability.After 24 hours of 1 mol/L hydrochloric acid or sodium hydroxide acid-base corrosion,the PM_2.5 filtration performance remained above 99.99%.It shows that the material has excellent acid and alkali corrosion resistance.