Gardner impact strength testing

Other impact strength tests that use gravity are the Gardner impact and Falling Dart tests. These are described in the following standards ... 

The relevant results of the tests are shown in Table 2. In our experience four parameters provide a very useful representation of the radiation tolerance of PP formulations. These are the color, tensile elongation at break, Gardner impact strength at 23°C, flexural deflection at peak load. 

Methods employed to determine the impact resistance of plastics include pendulum methods (Izod, Charpy, tensile impact, falling dart, Gardner, Dynatup, etc.) and instrumented techniques. In the case of the Izod test, what is measured is the energy required to break a test specimen transversely struck (the test can be done either with the specimen notched or unnotched). The tensile impact test has a bar loaded in tension and the striking force tends to elongate the bar (Chapter 5, Impact Strength). 

The strength properties more often specified for plastics materials are (1) tensile strength and elongation, (2) flexural strength, (3) Izod and Gardner impact, and (4) heat deflection temperature under load. Our purpose here is not to describe each test in detail but to point out some of the known effects that colorants and other formulation ingredients can have on these properties. Table 22.1 lists the ISO and ASTM test methods for most of the physical properties, and ref. 1 (pp. 7-112) describes each of the methods in detail. Table 22.2 lists typical values of the above cite four properties for selected thermoplastics. 

Nelson investigated the relationship between density and physical properties, e.g., flexural modulus, Gardner impact, heat distortion, ten-sile/flexural strength, coefficient of linear thermal expansion, dynamic mechanical testing, and creep testing. The specific gravity of the SRIM obtained was changed from about 0.3 to 1.2. 

One of the most important properties—impact resistance—has been tested in various conditions of acceleration of the impact weight (acceleration being recorded on an oscilloscope). In this way, the falling rate, impact strength, and kinetic energy transmitted to the film can be calculated by the Gardner test [41, 42],... 

Gardner light transmittance -77.1% haze - 12.6% gloss - 47% 108 96 Tensile strength retained is at yield impact is Izod 1/8 in Makrolon 3203 Miles Specimen Merlon M-50 UV stabilized, tinted tested, Makrolon 3203 is replacement... 

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