Degradation rule and hydrolysis mechanism of polyester particles temporary plugging agents
The effects of mass concentration of hydrochloric acid and NaOH aqueous solutions and temperature on the degradation performance of polylactic acid(PLA),polyglycolide acid(PGA)and poly(butylene adipate-co-terephthalate)(PBAT)were investigated.The degradation rule and hydrolysis mechanism of polyester particles as acid pressure temporary plugging agent were analyzed by FTIR,XRD and SEM,with the blocking performance further evaluated.The results showed that larger mass concentration of hydrochloric acid or NaOH solution and higher temperature led to shorter degradation time of PLA,PGA and PBAT,and faster degradation of PLA,PGA and PBAT in NaOH aqueous solution than in hydrochloric acid at the same mass concentration.Under the same conditions,of the three kinds of temporary plugging agents,PGA exhibited the highest degradation rates,PLA the middle,while PBAT the lowest.At the initial stage of degradation,the ester group began to hydrolyze,leading to pores appearing on the particle surface and slight decrease in the particle volume.As degradation progressed,hydrolysis preferentially occurred in the amorphous region,with crystallinity increased,carbonyl index decreased,hydroxyl index increased,surface pores increased,and the volume decreased further.At the later stage of degradation,the crystallization zone began to hydrolyze,the crystallinity decreased,and the molecular chain of the polymer was broken in large numbers until it was completely degraded.The blocking performance(pressure capacity)was ranked as PLA>PGA>PBAT in descending order.The breakthrough pressure of PLA,PGA and PBAT with a solid-liquid ratio(g∶L)of polyester particle temporary plugging agent to water was 11.7,10.9 and 7.5 MPa,respectively.The temporary plugging agent of polyester particles with a larger solid-liquid ratio displayed denser plugging layer and stronger bearing capacity.
万方数据
维普
