COMPARISON OF TENSILE AND MORPHOLOGICAL PROPERTIES WITH ABRASION RESISTANCE OF URETHANE FILMS

A study was made of the relationship between abrasion resistance determined by gloss loss in a ball mill abrasion tester (BMAT) and tensile energy to rupture for a series of urethane films. As expected, there was no correlation of abrasion resistance with rupture energy at ambient, but abrasion resistance did correlate well with rupture energy determined at minus 10 degree C for films in the brittle and transition regions. It did not do so in the rubbery region. The reason was found by Scanning Electron Microscopy (SEM). This showed that there was a difference between the mode of failure in the abrasion test and the tensile test. In the transition region, films in tension show crazing long before failure. But in abrasion testing, these crazes cause cracks which reduce gloss. Rubbery films must go to complete failure before showing effects which reduce gloss.