Why is the PVA of partial alcoholized easy to generate foam and how to eliminate the foam?

Since the partially alcoholized PVA contains more acetate groups, and the volume of the acetate group is much larger than the hydroxyl group, there is a large steric hindrance, so that the partially alcoholized PVA cannot form a compact crystal structure. It can only form loose structures with large spaces between molecules, which can absorb more air.In the process of boiling size,because the size has a certain viscosity,it provents the small bubbles from escaping from the size surface,and forms the accumulation of small bubbles,which produces greater energy,thus making the size overflow the size mixing kettle.If there still is bubble in the sizing box,a foam layer will form form on the surface of the sizing,which will affect the operation of the worker and also affect the sizing quality.

The way to eliminatiing the foam is to add an antifoaming agent in the sizing box or the mixing kettle.The antifoaming agent is actually a sufactant with few hydrophilic groups,which can reduce the surface tension of the foam and rapidly break the foam,thereby reducing the accumulation of the foam and achieving the purpose of defoaming.