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Chemically and heat reactive, expandable sealants are used as “acoustical baffles” in the automotive industry. These acoustic baffles are used to impede noise, water and dust propagation inside of structural components and body cavities. Use of these sealant materials has grown significantly as the demands to improve vehicle acoustic performance has increased. Various test methods have been developed to quantify the performance of these materials through direct comparison of material samples. These investigations use standardized testing procedures to characterize the acoustic performance of a material sample on the basis of controlled laboratory test conditions. This paper presents a step in the progression of evaluating acoustic baffle performance in the vehicle. Standard experimental techniques are used to investigate the influence of the baffles on the vehicle acoustic performance.

A variety of expandable sealants are used to fill vehicle body cavities to impede noise, water, air, and dust from entering (and exiting) the passenger compartment. This paper compares three sealant technologies used for filling body cavities. The technologies are rubber-based elastomeric preformed parts; thermoplastic elastomeric preformed parts, and two-component polyurethane that is foamed-in-place directly in the vehicle body cavity. The following comparisons are made between the three technologies: application methods and issues, cost, material properties and acoustical performance.

Driven by global pressures of weight reduction and cost savings, suppliers of specialty sealing and bonding products to the automotive industry have responded by expanding the focus of their product development activities. OEM engineering practices have brought about significant changes within the specialty sealing and bonding supply base. The successful suppliers in this market have responded to these pressures and initiated changes in the processes through which their materials are developed and released into production. In an industry historically populated by chemists and manufacturing process engineers, new requirements have led to an increase in application engineers and technical specialists, providing the necessary vehicle development expertise to the sealant industry. To support these expanded roles, new research and development facilities and associated advanced technologies have become a critical requirement.