How Swelling affects the anti-shrinkage effect of pvac resin

Why should a good dissolved PVAc should be put aside for a while before usage? If dissolves not so well, it will affect the pvac's effect of low shrinkage. 

PVAC will swell phenomenon in the process of styrene dissolved into the solution, this process is accompanied with the dissolution and homogenization; this process according to the dissolution apparatus and methods are different, generally need 4-72 hours; it also explains why PVAC solution after a period of time, the reason of the effect will be better.

Polyvinyl acetate PVAC (Polyvinyl Acetate) and styrene in solution after a period of time (usually 4-72 hours), in the infinite swelling, forming a homogeneous polymer solution, this time is applied to the SMC/BMC material, the anti shrinkage effect is the most significant.

There are two kinds of swelling: infinite swelling: linear polymers dissolved in a good solvent, unrestricted absorption of solvent until dissolved into homogeneous solution. Therefore, dissolution can also be regarded as the result of unlimited swelling of polymers. Example: natural rubber in gasoline; PS in benzene; PVAC dissolved in styrene limited swelling for crosslinked polymer and linear polymer in poor solvents, swelling only to a certain extent, after contact with a solvent regardless of how long, the amount of solvent inhalation increases no longer, and always maintain balance system two-phase state. The swelling degree Q (i.e., the swelling factor) was used to characterize this state, and was measured by equilibrium swelling method