constrained layer damping structures are often based on viscoelastic layers of iso - octyl acrylate : acrylic acid or analogous copolymers . as the acrylic acid content is increased , the peak damping temperature also increases ; unfortunately , however , the copolymer becomes more brittle and susceptible to shock , especially at low temperatures . incorporating small amounts of rubbery polymer particles in the viscoelastic copolymer alleviates this problem .