Performance and application of PPS filter bag materials-polyphenylene sulfide fiber
PPS filter bag (polyphenylene sulfide) fiber has excellent heat resistance, smoldering, corrosion resistance and mechanical strength similar to that of Nomex fiber; it is suitable for processing into high performance fibers. All these new properties are mainly determined by its fiber structure.PPS filter bags are widely used in coal fired boilers.
The structural formula of PPS is a large molecular chain formed by connecting sulfur atoms on the opposite side of the benzene ring. It is a linear polymer with a semi crystalline property. The crystallinity of the general PPS fiber is in 50%-60%. As a filter PPS fiber, the fiber section of the fiber basically round and three leaf types.
Physical properties of PPS fiber:
Because of high crystallinity, good mechanical properties and stable size, polyphenylene sulfide fibers have small deformation in the process of use, and can fully meet the requirements of use. The textile processing properties of PPS fibers are similar to most conventional textile fibers and are easy to weave and process.
Chemical stability of PPS fiber:
PPS fiber has good chemical stability and can maintain its original performance under extremely bad conditions. Its chemical stability is second only to polytetrafluoroethylene fibers. It is suitable for high end applications in harsh environment. At high temperature, PPS fibers can be placed in different inorganic reagents, and the original tensile strength can still be maintained after a week. After 2 weeks in 93 and 10% sodium hydroxide solutions, the strength of the solution did not change significantly. It also has good properties of organic reagents. Besides the slight influence of toluene at 93 C on its strength, in organic solvents such as carbon tetrachloride and chloroform, its strength can not change even at the boiling point for a week, and the strength of acid and acetic acid at temperature of 93 C has no effect on its strength.
To sum up, the chemical stability of PPS fiber is second only to the tetrafluoroethylene fiber, only under high temperature and strong oxidizing agent can the fiber be degraded, so the PPS fiber is suitable for the filtration of many strong corrosive chemical medium.
Temperature properties of PPS fiber:
PPS fiber has excellent thermal stability and excellent heat resistance. The melting point reaches 285 degrees C, which is higher than the other melt spinning fibers currently in industrial production. Therefore, it is more stable in the process of use. The products made by PPS fiber are very difficult to burn. Although it will burn in the flame, once the flame is removed, the combustion will immediately be burned. At the time of combustion, it is yellow orange flame and produces a small amount of black soot, which does not fall off and forms residual coke. It shows low delayed combustion and smoke density. The limit oxygen index can reach 34%-35%, and it will not burn under normal atmospheric conditions. For example, it is used as filter fabric for the bag filter chamber of coal fired boiler. In the wet acid environment, the long term use temperature of PPS fiber is 150-170 C, the maximum use temperature is 190 degrees C, and the service life of the fiber is about 3 years.