Test method tensile impact

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 materials and morphological parameters are usually studied as function of test temperature and test speed. The Izod method as function of temperature (9,10) is standard. Also studied is the Charpy impact behavior, both as a function of test temperature and test speed (12). With a notched tensile impact test, both test speed and test temperature can easily be varied (I, 2,13). 

Both the previous two methods require the test piece to be sufficiently rigid for buckling of the specimen under test to be negligible. For thinner section materials and for those exhibiting a high elongation before fracture, the tensile impact test may be the only viable... 

The method of instrumented notched tensile-impact testing is preferably used for elastomeric materials which cannot be tested under other impact-like loading conditions. However, also for thermoplastics, especially thermoplastic films, also the characterization of the fracture behaviour under impact loading can be necessary. Therefore, the following Tables show a summary of available data of fracture mecha-nics tests under impact-like loading conditions for thermoplastics and elastomers. 

The deterioration of mechanical properties is normally assessed by measurements of fracture resistance by pendulum impact test methods or slow speed flexural strength measurements and by ensuring that the surface of the specimens subjected to tensile stresses corresponds to the face exposed to the UV (or weathering) source. These tests are generally more meaningful than nondestructive tests, such as modulus measurements, since the chemical changes and the creation of fine cracks (often invisible to the naked eye) may involve only a very fine layer on the surface of the exposed samples. 

Tensile impact testing is used to determine the impact resistance of samples that are too thin or too flexible for impact beam or impact plaque testing but cannot be considered films. It involves strain rates that are intermediate between those used for impact beam testing and those used for conventional tensile testing. This procedure is performed according to ASTM Method D 1822. 

ISO 9653 1998 Adhesives - Test method for shear impact strength of adhesive bonds ISO 9664 1993 Adhesives - Test methods for fatigue properties of structural adhesives in tensile shear... 

Following are some properties of AECP explosion /emp(PA method) 305—10°(5 sec) impact test with 2kg wt—detonated at 12" bygroscopicity(% gain in wt at RT and 77% RH) 23% after 6 days and 22.3% after 13 days thermal stability—relatively stable at 85° for long periods of time but decomp extensively at 125° within a week tensile strength—decreases with increase in perchlorate content solubility—insol in common solvents, sometimes dissolved at elevated temps with decompn, swelled in some polar liquids dissociated to some extent in HaO compatibility with NC—incompatible... 

The impact of thermal shock on the properties of a ceramic or a CMC is assessed by means of both destructive and non-destructive testing methods. Flexural or tensile (mainly for CMCs) tests of suitably-sized thermally shocked specimens are usually employed to measure retained mechanical properties as a function of the temperature difference. The temperature differential for which a significant drop in property values is observed is the A A- For monolithic ceramics and particle- or whisker-reinforced CMCs the property under investigation is usually strength, whereas in fibre-reinforced CMCs a drop in Young s modulus is usually a better indication of the onset of damage. 

Test Method for Impact Strength of Adhesive Bonds Test Method for Tensile Properties of Adhesive Bonds Test Methods for Pressure Sensitive Adhesive Coated Tapes Used for Electrical and Electronic Applications... 

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. 

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