AbstractA correlation has been made between dynamic mechanical properties and impact resistance of a multicoat paint system. It has been determined that the shear or rigidity modulus and damping of free primer films are some of the parameters that control the impact characteristics of the system. Those films of low modulus and high damping show the best chip resistance. A series of physical and chemical modifications were made on the primer and chipping results were compared with dynamic mechanical properties of free paint films. It was found that increasing cure temperature, addition of catalysts, decreasing the oil length of the resin, increasing the amount of pigmentation and increasing the tension and strain rate all led to increased paint chipping and increases in the modulus of rigidity. Two new primers were synthesized which incorporated the above results and were found to give increased gravel impact resistance.
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