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Elastomeric modifiers have been commonly used in friction lining compounds to provide resilience, stability of frictional characteristics, reduced wear and improved fade resistance as well as providing some level of noise and vibration dampening. Thermal and frictional characteristics according to SAE J2430 will be compared between friction linings made with a virgin powder of Styrene Butadiene Rubber (P-SBR), a powder of reclaimed Styrene Butadiene Rubber (Tire Scrap) and a highly defined morphology powder of Nitrile Butadiene Rubber (DM-NBR). Unique performance advantages of friction linings made with higher loading levels of DM-NBR powder and reduced copper content will also be discussed.

Flexibility, oil resistance, and the need for heat resistance to 150°C-plus temperatures have traditionally limited automotive design engineers to two options - thermoset rubber or heat-shielding conventional thermoplastic elastomers (TPE). Both of these options present limitations in part design, the ability to consolidate the number of components in a part of assembly, and on total cost. This paper presents a class of high-performance, flexible thermoplastic elastomers based on dynamically vulcanized polyacrylate (ACM) elastomer dispersed in a continuous matrix of polyamide (PA) thermoplastic. These materials are capable of sustained heat resistance to 150°C and short-term heat resistance to 175°C, without requiring heat shielding. Recent advancements in blow molding and functional testing of the PA//ACM TPEs for automotive air management (ducts) and underhood sealing applications will be shown.

Compressive Stress Relaxation (CSR) testing is challenging due to the different sample geometries, fixtures, aeration, and temperature cycles. Ageing environments such as hot air, static fluids, and aerated fluids contribute significantly to this challenge. ASTM and Original Equipment Manufacturer (OEM) standards allow a fixture two hours to equilibrate after immersion in ageing medium before testing. Experience has shown that the sample may not be at room temperature thus leading to possible errors in force readings. The focus of this paper is to conduct thermal cycle testing on typical rubber gasket compounds in order to determine their properties in such environments. Various thermal cycling methods were performed in order to determine the influence on the compound properties.

Thermoplastic vulcanizates (TPVs) afford many advantages in terms of part design, processing methods, and part cost. Due to temperature and oil resistance limitations, current generation TPVs (including those based on ethylene-propylene rubber [EPDM] and polypropylene [PP]) and copolyester have had only limited applicability in many powertrain sealing, hot air duct, and boot applications. This paper will introduce a new class of heat and oil resistant TPVs. A polyacrylate (ACM)//polyamide based TPV representative of this class will be compared to current generation TPVs and typical thermoset rubber. When tested out to 1500 hrs at 150°C, the ACM//polyamide TPV will be shown to exhibit less than 50% loss of tensile strength and ultimate elongation.

The current method for testing and evaluating sealing material candidates is plagued with concerns, issues and problems. Compressive Stress Relaxation (CSR) testing is challenging to operate. There are at least four different intermittent fixture types (Jamak, Jones-Odem, Wallace and Wykeham-Farrance) and one continuous compressive stress relaxation, CCSR fixture (Elastocon). Complicating this are four different sample geometry types and the potential use of aeration. The focus of this paper is to address these issues and offer some comparisons of the new ACM (polyacrylate) polymers that have been developed for the increasing temperature requirements in an engine compartment.