Elmendorf test

For both the tongue and Elmendorf test methods, it is important to observe the behavior of the specimen as the tear is propagated. In cases where the yams in the test direction are much stronger than the perpendicular yams, it is sometimes difficult or impossible to propagate the tear in the desired direction. In this case, a crosswise tear results. Tear resistance is primarily a function of fabric constmction. Loose, open weaves such as cheesecloth tend to resist tear, whereas tight weaves tend to tear easily. In the open weave, the concentrated force field at the point of tear is dissipated by the compliance of the fabric stmcture to accommodate the stress field, thereby distributing the force over a greater number of yams. 

The standard pendulum-type measurement of tear strength is known as the Elmendorf test. A schematic illustration of a typical instrument used in the pendulum-type measurement is shown in Figure 31. The geometry of the specimen, specified by the ASTM method, is illustrated in Figure 32. The specimen contains a precut slit and is so shaped that the tear must traverse a fixed distance... 

Testing of Fabrics for Tensile Properties. Unexposed and exposed pieces of L-4 Blue Wool fabrics were tested in the warp and fill direction for tearing strength by ASTM Method D-1424 on an Elmendorf tester (11). 

To determine whether or not changes in color were accompanied by fiber damage, unexposed fabric and several fabrics exposed to the xenon-arc source for 550 kj/m2 (AE from 1 to 3) were tested for tearing strength by the Elmendorf method (11). Before exposure, the tearing strength of the blue wool fabric was 2040 g in the warp and 1710 g in the fill direction. For all other fabrics tested after exposure to light, the... 

Mechanical Testing. Tensile strength tests were performed with an Instron tensile tester as per the American Society for Testing and Materials (ASTM) D-1682, and tear testing was done with an Elmendorf apparatus as per ASTM D-1424 at 21 °C and 65% rh, after conditioning the specimens for at least 24 h. Results reported are the average of three tests. 

ASTM D1922, usually known as the Elmendorf tear strength (related to test originally devised for paper and board), is carried out in the machine (MD) and cross (CD) direction of the material. Measured as kN/m. Test D689-44 also applies for films. 

An alternative approach is to apply a force by means of a pendulum, which is the basis of the widely used Elmendorf apparatus. Essentially, part of the energy stored in the pendulm is used to produce the tearing (and any deformation of the test piece), and the magnitude of this is indicated by the energy lost compared to there being no test piece. The incentive for this approach originally was probably to have a relatively simple and cheap stand-alone apparatus. 

Tear strength Elmendorf tear test ASTM D 5734... 

Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method, Elmendorf Tear. Primary Film Test Method ASTM D1922. Tear strength is the force necessary to eontinue tearing a sample after a nick has been made it is reported in grams. 

Elmendorf Tear testing can be performed on three types of standard samples however, the constant radius sample is the preferred test sample for plastic films. (See Fig. 2.) This sample provides a constant radius from the start of the tear strength measurement—useful for materials where the tear may not propagate directly up the sample as in-tended.f ]... 

In tests of 20-mil films blown from comparable melt index pol)miers, Dow Primacor copolymers showed clearly superior Elmendorf tear strength over EVA, and up to ten times the tear strength of the ionomer. In cast films, Dow Primacor copolymers can even offer more balanced tear strength than comparable linear low material... 

Testing of plastic films - Tear test using trapezoidal test specimen with incision Testing of paper - Determination of tearing resistance according to Elmendorf (single tear tester)(withdrawn replaced by ISO 1974 2012)... 

Intrinsic tear g Elmendorf A tear test using 86 345 63 300... 

To determine tear resistance (Elmendorf), a sample is torn with the help of a pendulum device starting from a predetermined cut. The work required for a tear of a given length is measured. The test is described in ISO 1974 (1990). 

As far as the mechanical properties are concerned, the tear (test name Elmendorf tear), impact (test name dart drop), and tensile strengths give an indication of the mechanical strength of the tubular film. Some of these properties and the effect the processing parameters have on them were discussed in Section 1.2. The amorphous as well as the crystalline orientation developments during the blowing process depend on... 

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