Abstract: A co-injection molded air intake manifold shell comprises an inner and outer skin layer separated by a sound absorbing or sound insulation core. Each skin layer is composed of a polyamide resin which, optionally, contains glass fiber reinforcement and high specific gravity fillers such as barium sulfate or tungsten. The sound insulating core is composed of a high density material having a foam structure, such as a polyamide resin. Skin layers are provided with a plurality of pockets to permit distribution of localized lumped masses at predetermined locations tailored to increase noise transmission losses. A single layer air intake manifold shell having non-uniform thickness is also provided. The thickness of the single layer air intake manifold shell is larger over preselected noise sources of larger amplitude to maximize noise attenuation for a nominal air intake manifold shell thickness.

Abstract: A co-injection molded air intake manifold shell comprises an inner and outer skin layer separated by a sound absorbing or sound insulation core. Each skin layer is composed of a polyamide resin which, optionally, contains glass fiber reinforcement and high specific gravity fillers such as barium sulfate or tungsten. The sound insulating core is composed of a high density material having a foam structure, such as a polyamide resin. Skin layers are provided with a plurality of pockets to permit distribution of localized lumped masses at predetermined locations tailored to increase noise transmission losses. A single layer air intake manifold shell having non-uniform thickness is also provided. The thickness of the single layer air intake manifold shell is larger over preselected noise sources of larger amplitude to maximize noise attenuation for a nominal air intake manifold shell thickness.

Abstract: The invention relates to nylon compositions having improved surface aesthetics while maintaining its physical properties and to a method for preparing molded articles of from such nylon compositions. The nylon composition is composed of a substantially uniform blend of nylon 6,6,6 copolymer of from about 65 to about 75 parts by weight of caprolactam and from about 25 to about 35 parts by weight of hexamethylenediamine and adipic acid in a 1:1 ratio; together with a second polyamide which is nylon 6 homopolymer. The first polyamide is present in the overall composition in an amount of from about 7 to about 20 weight percent and said second polyamide is present in the overall composition in an amount of from about 80 to about 83 weight percent. The nylon compositions are useful to create injection molded articles having a good surface appearance and good performance at a low cost.