1.1 This part of PS 4371 specifies a method of determining the force required to propagate a tear through a specified distance and from a specified slit, cut in a test specimen of thin flexible plastic sheeting or film, under specified conditions of loading.

The upper limit of thickness that can be tested depends on the tearing force of the material in relation to the capacity of the testing machine.

Materials that can be tested according to this method include flexible poly(vinyl chloride) (PVC) and polyolefin films, but variable elongation and oblique tearing effects on the more extensible films may cause poor reproducibility of test results. This method may not be suitable for testing more rigid materials such as rigid PVC, nylon and polyester films.

1.2 The tear resistance test specified by this method is applied to specimens cut from semi-finished and finished products. The test is suitable for the control of production and manufactured products as well as for acceptance or rejection testing under specifications for semi-finished and finished products, provided that it has been demonstrated that the data for a particular material are acceptably reproducible.

1.3 There is no direct linear relationship between tearing force and specimen thickness. Data from this method are expressed as tearing force in newtons, with specimen thickness also reported. Only data obtained at the same thickness should be compared because sets of data from specimens of dissimilar thickness are generally not comparable.