ASTM test methods impact resistance

Organic coatings are commonly evaluated using salt water immersion, salt fog or spray, modified salt exposure tests (e.g., salt fog with added SO2), and various cyclic exposure tests. Humidity exposure and water immersion, and, for many applications, physical resistance tests (adhesion, impact resistance, etc.) are widely used preliminary tests. Standard methods for most of these tests are given in compilations of standard tests such as the Annual Book of ASTM Standards (16). Test methods have been extensively reviewed (e.g., 17-23). 

ASTM Test Method Gen. Purpose Impact-Resistant Poly (methyl Methacrylate)... 

Source Reprinted from ASTM C 131, Standard test method for resistance to degradation of small-size coarse aggregate by abrasion and impact in the Los Angeles moch/ne. West Conshohocken, Pennsylvania, US ASTM International, 2006. With permission ( ASTM International). 

Table 3 compares properties of PTT, PET, and PBT (40). They were measured on injection-molded samples using ASTM test methods. Tensile strength, flexural modulus, and notched Izod impact of PTT fall in between those of PET and PBT. All three polymers have similar electrical properties except for PET which has lower volume resistivity. The lower moisture absorptions of PTT and PBT are due to the high crystallinities from fast crystallization. 

ASTM D2794-93, Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact), 2004. 

Methods of Test for Impact Resistance of Plastics and Electrical Insulating Materials, ASTMD 256-54T, ASTM Standards, Part 6, p. 182 (1955). Also ASTM D-256-56, ASTM Standards 1956. American Society for Testing Materials, Baltimore, 1955 and 1956. 

The most common test for impact resistance of plastics is the Izod pendulum method, ASTM D256, often used with rigid PVC. In this method, either the mass of the weight or the extent of arc can be used to specify failure. It is differentiated into notched and un-notched Izod the former, notably more severe, uses a sample with a cut notch of specific dimensions. With suitable instrumentation, Izod measurements can be extended to determination of low-temperature impact resistance. 

Tables 4—6 Ust ASTM methods used for the characterization of PB and PMP. A number of specialized methods were developed for testing particular articles manufactured from polyolefins several of these determine the performance of PB and PMP film, including the measurement of the film s dart impact strength and tear strength. Dart impact strength is measured by dropping a heavy dart with a round tip on a stretched film. Tear resistance, which reflects the film s resistance to tear propagation, is measured with the Ehnendorf tear tester. Two values for the tear strength are usually reported, one in the machine dkection of the film and the other in the transverse dkection. Pipes manufactured from PB are tested by pressurizing them internally with water the time-to-burst failure is determined at various temperatures (46). The standard test method for haze and luminous transmittance (ASTM D1003) is used for the measurement of PMP optical characteristics.

Testing. Various test methods are provided by ASTM (16). These iaclude pigment tests of importance such as chemical analysis, presence of oversize particles, oil absorption, particle size distribution, degree of dispersion, presence of soluble components, etc. Numerous tests are also given by ASTM for the properties of filled and unfilled polymers. These iaclude, for example, such properties as impact resistance, stiffness, viscosity, tear resistance, hardness, color, and electrical resistivity. 

ASTM D3029, Test Method for Impact Resistance of Rigid Plastic S heeting or Parts by Means of a Tup (Falling Weight), Vol. 8.02, ASTM, Philadelphia, Pa., 1993. 

Impact Test. Impact testing is of importance because adhesives, like most polymeric materials, are sensitive to high rates of application of force. The resistance of an adhesive to impact can be determined by ASTM D 950. This test is analogous to the Izod impact test method used for impact studies on materials. 

This test method was proposed by Senbetta16. Its original purpose was to evaluate the impact resistance of floor materials in terms of the capacity to resist surface disintegration due to repetitive low level impact. Instead of floor materials, this test was employed to measure the influence of plastic fillers on the concrete resistance to repetitive low impact. The specimens which were used in the test were nine 2-in. (50-mm) concrete cubes made with mix No. 2. The test uses the Los Angeles (LA) abrasion machine, which is traditionally utihzed to test aggregates according to ASTM C 131 and C 535 specifications. 

ASTM D256-05a Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics, p. 1-20, American Society for Testing and Materials, Philadelphia, 2005. 

There are standard test methods for testing the impact strength under ordinary conditions. In addition, there is an ISO Standard with respect to bullet resistance of protective clothing, but remarkably there is no ASTM Standard with respect to this topic. 

Test methods for determining the izod pendulum impact resistance of plastics. ASTM Standard ASTM D256-06a, ASTM International, West Con-shohocken, PA, 2007. 

Impact Resistance of Plastic Film by the Free-Falling Dart Method. Primary Film Test Method ASTM D1709 Additional Test Method ISO 7765-1. A weighted dart is dropped from a standard height onto a taut sample. Depending upon the expected impact strength of the test sample, either method A or method B is chosen. The method defines the dart size and the drop height for the dart. Test method A specifies a dart with a 38 mm diameter dropped from 0.66 m. Test method B specifies a dart with a 51 mm diameter dropped from 1.5 m. 

Pendulum Impact Resistance of Plastic Film. Primary Film Test Method ASTM D3420. 

ASTM D256 Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics. Used to determine the resistance of a plastic specimen to impact by a pendulum-type hammer. Specimens contain a milled notch and depending upon the test method, failure may be brittle or ductile. Test results are reported in terms of energy absorbed per unit of specimen width or per unit of cross-sectional area under the notch. 

ASTM D1709 Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method. 

ASTM D3420 Standard Test Method for Pendulum Impact Resistance of Plastic Film. Used to determine the resistance of film to impact-puncture penetration at ambient conditions. Also called Spencer Impact. 

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