Review on Toughening of Phenolic Foams

Two methods of toughening the phenolic foam were summarized. One was physical blending toughening which introduced modifiers into the foam,such as the flexible polymer,nano-particles and fibers. The other method was chemical toughening which connected flexible chains with matrix resin through covalent bonds. Besides,preparation methods of low-acidity phenolic foams by improving the frothing technics or adding reactive curing agent were briefly introduced.