浸泡7天后，试件被从溶液中拿出，擦干表面溶液，记录质量为m7d, 样品

After immersing for 7 days, the test piece was taken out of the solution, and the surface solution was wiped dry. The recorded mass was m7d, the mass measurement accuracy of the sample was 0.001 g, and the mass change rate ((m7d- m0)/m0) can be calculated according to each solution Density can be calculated per unit mass volume change.

After 7 days of immersion, the test piece is taken out of the solution, drying the surface solution, the recorded mass is m7d, the quality measurement accuracy of the sample is 0.001 g, the mass change rate (m7d-m0)/m0) can be calculated according to the density of each solution unit mass volume change.

After soaking for 7 days, the specimen is taken out of the solution, the surface solution is wiped dry, and the recorded mass is m7d. The mass measurement accuracy of the sample is 0.001 g. the mass change rate ((m7d-m0) / M0) can be calculated, and the volume change per unit mass can be calculated according to the density of each solution.<br>