An Examination of the Crack Growth Behavior of an Ethylene-co-Vinyl Acetate Hose Compound
|Date Published||January 1, 2006|
Ethylene-co-vinyl acetate (EVM) copolymer is particularly suited for use as a covering in hose applications. According to ASTM D 2000, EVM is a EE material (up to 175°C heat resistance) and its oil resistance depends directly on the amount of vinyl acetate (40 to 90%) incorporated into the polymer chain. Its inherent ozone and high heat resistance along with its ease of processability for extrusion applications makes EVM an excellent material of choice for hose compounds. This study will investigate the crack growth properties of a basic EVM hose compound in which the filler type (carbon black or mineral filler) and peroxide concentration (crosslinking level) is varied. The rate of crack growth will be followed by use of a tear analyzer apparatus which can help to predict the average lifetime of the test samples as a function of deformation. It was found that carbon black fillers, in particular N550 type black, produced the lowest crack growth rates. Mineral fillers are not recommended for use due to high compression set and high crack growth rates. In light of the results, EVM for use as the tube and cover compound with aramid reinforcement is highly recommended in turbo charger systems.