The effects of HPMC substitute type on the water penetration are concentrated on the initially short time, which is considered to be the time for HPMC to form a hydrogel.

• HPMC取代度类型对水渗透作用的影响集中表现在最初较短的一段时间内，这段时间是指HPMC形成水凝胶的时间。水凝胶形成后，水渗透进入凝胶的速率是恒定的。