Polyvinyl acetal modified phenolic resin
The most widely used industrial application is the modification of phenolic resin with polyvinyl acetal, which can improve the resin's adhesion to glass fiber, improve the brittleness of phenolic resin, increase the mechanical strength of composite materials, and reduce the curing rate, thus reducing the forming pressure.
The modified phenolic resin is usually prepared by using ammonia or magnesium oxide as catalyst.
The modified polyvinyl acetal is a high polymer with different proportion of hydroxyl, aldehyde and acetyl side chains.
The relative contents of hydroxyl, acetyl and aldehyde in the polyvinyl acetals of uranide;
The chemical structure of the aldehyde in which the film was made.
The addition of pva reduced the concentration of phenolic resin in the resin mixture, slowed down the curing rate of the resin, made low pressure molding possible, but the heat resistance of the product decreased.
Polyamide modified phenolic resin