Experimental Research On Durability And Failure Process Of PPS

The air pollution problem increasingly become more and more serious with the rapid progress of industrialization,so as the wide application of bag filter which embodies the excellent characteristic of dust control effect.PPS filter materials has been widely applied in fuel gas treatment coal-fired power plants due to its advantages of high temperature resistance and strong chemical stability.The requirement on exhaust gas of burning coal boiler is very harsh and corresponding temperature stabilize at around 160-200 ?,which also contains corrosive gas such as Sox and NOx.Consequently studies on the failure process and durability of PPS is of great significance on economic and environmental protection.First of all,independently designed test decive and method on durability performance has been employed to study the property of PPS in this paper.Effect of temperature,time and filtration rate on PPS has been considered.The results indicated that its strength and elongation at break decrease and crystallinity increase,which means the embrittlement of PPS,with the increasing temperature.In addition,effect of filtration rate on properties of PPS is not significant.Effect of oxygen concentration on the failure process of PPS fiber also has been studied.The integral Coats-Redfern method based on single heating rate and the iso-conversional Flynn-Wall-Ozawa(FWO)and Kissinger-Akahira-Sunose(KAS)methods based on multiple heating rates were employed and the results indicated that only one stage occurred under pure nitrogen atmosphere while two stages occurred under oxidative atmosphere.Maximal mass loss rate and apparent activation energy of the first stage varies little and corresponding kinetic parameters of the second stage increase linearly with increasing oxygen concentrations.In addition,kinetic parameters calculated meet the kinetic compensation effect,initial temperature of second pyrolysis stage is greater than isokinetic temperature Ts and consequently apparent activation energy and pyrolysis rate of PPS increase with the increasing ocygen concentrations.Due to the compensation effects in the oxidative degradation process of PPS,pyro-lysis rate increases with the increasing actication energy when temperature is greater than Ts,correspondingly activation energy and pyrolysis rate increase with the increasing oxygen concentrations when temperature is less than Ts.Consequently combined effects of activation energy,pyrolysis rate and isokinetic temperature should be taken into consideration in the thermal stability evaluating process of PPS.Failure and damage reasons of PPS are multiple in practical application.According to experimental result,environmental factors for PPS should be controlled properly,temp-erature and oxygen concentration should not be exorbitant and service time ought to be controlled in a reasonable range.In addition,inspection and exchange of filter bag regularly is also needed.