Study on Preparation and Degradation of PLA/PGA Composite Fiber for Temporary Plugging Agent

Temporary plugging agent is an important material for increasing production in oil and gas exploitation. With the improvement of environmental protection requirements, biodegradable temporary plugging agent material has become the preferred material in current oil and gas exploitation. Polyglycolic acid is the simplest linear aliphatic polyester with the fastest degradation rate. The degradable temporary plugging knot made of polyglycolic acid has been applied in oil and gas exploitation. However, polyglycolic acid has some problems, such as fast degradation rate and short shelf life, which greatly limit its application. In this work, the sheath-core composite fiber with ' O' profile was prepared by composite melt spinning method with poly(lactic acid) as the sheath and poly(glycolic acid) as the core layer. The morphology, degradation, thermal properties and crystallinity of the composite fibers with different sheath/core ratios were studied. The results showed that the ' turning point' of the dissolution rate of composite fibers at 70 °C was at 6 h of degradation. Before this point, the dissolution rate of composite fibers was within 3wt%, and then, the dissolution rate of composite fibers was almost increased linearly. After, the dissolution rate of composite fibers with sheath/core ratio of 20/80 could reach 23. 2% after 24 h of degradation. The scanning electron microscope photos showed that after 24 h of degradation, the smaller the thickness of the polylactic acid layer, the higher the degree of fiber degradation. In the composite fiber with a sheath/core ratio of 20/80, the polylactic acid layers cracked, causing the polyglycolic acid in the core layer to degrade and break into small segments along the fiber axis. The results of thermal properties showed that the crystallinity of polylactic acid increased with degradation time, while the crystallinity of polyglycolic acid increased first and then decreased with degradation time. The results of wide-angle X-ray diffraction showed that the grain size of polyglycolic acid is small, especially the length of grain along c-axis was only about 34 nm. The strength retention rate of fibers and the pH value of the degradation solution are directly proportional to the thickness of the sheath layer. This work provides a new way to prepare temporary plugging agent. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.