Development of a Novel Polyolefinic Thermoplastic Vulcanizate for Fuel Line Covering Applications

Blends of Thermoplas™, a TPE based on blends of polypropylene and ethylene/α-olefin copolymers with various additives were prepared using a twin screw extruder. The mechanical, impact, rheological, thermal and chemical properties of the resultant blends and those of two commercially available TPE's (CTPE1 and CTPE2) used in fuel line covering applications were measured. Thermoplas™ had a percentage elongation at break of up to three times greater than both commercial materials, was more flexible, and had better impact strength at 25°C and -40°C. Thermoplas™ was less viscous than CTPE1 and CTPE2 in the shear rate range normally experienced during tube extrusion, when measured using capillary rheometry techniques. The lower viscosity of Thermoplas™ was also evident during cross-head extrusion trials, with line speeds for certain grades 50% greater than that achievable with CTPE1 and CTPE2. Thermoplas™ passed all heat aging and chemical conditioning tests to SAE J2027.