The invention relates to a method for improving mechanical properties of an
aramid fiber in a
supercritical fluid through stretching orientation. A
supercritical carbon dioxide fluid is utilized for partially destroying interaction of a PPTA (poly-p-
phenylene terephthamide) molecular chain in the
aramid fiber under the action of certain tension, and the molecular chain is further oriented, so that the
aramid fiber with good properties is obtained. The method for improving the mechanical properties of the aramid fiber in the
supercritical fluid through stretching orientation mainly comprises the following steps: ensuring that the aramide fiber maintains certain tension in a closed container, introducing CO2 into the container at a certain temperature, so that the internal space of the closed container is in a supercritical CO2 state, carrying out swelling reaction for a period of time, and slowly releasing pressure, thus the highly stretching-oriented aramid fiber is obtained. The method for improving the mechanical properties of the aramid fiber in the
supercritical fluid through stretching orientation guarantees that the aramid fiber is in a stretched state in a reaction process, so that orientation degree and
crystallinity of a molecular chain are increased while stretching tension is changed,
crystal particles are largened, and crystals are more and more complete.