ASTM tests impact strength

Mechanical Testing. Impact strength was measured using ASTM method D-250-56 and is reported in foot-pound per inch of notch. 

The routine compositional and functional testing done on the adhesives includes gas chromatographic testing for purity, potentiometric titrations for acid stabilizer concentrations, accelerated thermal stabiUty tests for shelf life, fixture time cure speed tests, and assorted ASTM tests for tensile shear strengths, peel and impact strengths, and hot strengths. 

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.

Impact resistance is related to impact strength. Two of the most utilized tests are the Izod (ASTM D-256) and Charpy (ASTM D-256) tests illustrated in Figure 14.16. 

Bis(2,3-dibromopropyl) fumarate has been used as a fourth monomer in nitrile rubber- and graft-type ABS materials giving flame-resistant polymers. At least 10% bromine incorporation is required to pass the Underwriters Laboratories Subject 94 test. The graft-type materials fail at 7-10% bromine only because of dripping. Both types pass the ASTM D-635 test with 7% or more bromine. For the impact strength to be equivalent to that of conventional ABS, the fourth monomer must be present in both the rubber and resin phases. Thermal stability is marginal but can be improved with typical PVC stabilizers. 

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. 

Fig. 22 Evolution of the E-modulus and Izod notched impact strength of composites based on PP (MFR 4.2 dg min 1) and increasing amounts of talc. Injection molded samples tested according to ASTM D790. Data taken from Fujiyama [40]...

E, ultimate tensile strength, Oy, yield strength, Oy, and ultimate elongation, e, were determined. In all cases, three to four specimens per sample were obtained that did not fail prematurely. Impact tests were conducted according to the ASTM test D-256-70, method B (Charpy type, notched). On the average, 4 to 5 specimens were tested. 

Tests may be on the basic plastic or the material available as a film, sheet, component or container. One test is the Charpy notched impact strength, DIN 53453 standard. This involves either un-notched or notched samples tested against impact over a range of temperatures. The resilience is measured as kg/cm. The test is carried out on samples 15x 10x2 mm. ASTM D256 ft lb/in notch is found as the Izod notched impact test. 

For polymer sheets, the notched Izod impact strength is often reported (ASTM D256). In this test, as well as the Charpy impact test in the same ASTM standard, the polymer sample is subjected to an impact from a falling hammer, and the... 

A variety of tests are available for determining film quality. Many are based on ASTM standards. For example, tests for permeation of oxygen, water vapor, or other substances may be carried out, and will be discussed in Chapter 14. Tests for impact strength, tensile strength, tear strength, and other mechanical properties are important for many applications. Tests particularly related to quality control in the film production process include those that relate in some fashion to the appearance of the film. 

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. 

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. 

Impact Strength - The impact behaviour of PES is good it is not as outstanding as that of Polycarbonate but it shows better impact perfoimance than that of nylons or acetals. PES cannot be broken in the unnotched Izod test, and a notched Izod (ASTM D 237) has a value of 1 6 ftlb/in notch it is particularly resistant to crack initiation and PES is ev a. tougher after it has absorbed its equilibrium amount of water. 

ASTM D 4508-98. Standard test method for chip impact strength of plastics. 

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