Flexural modulus test

The variation of the damping factor (tan 5) with temperature was measured using a Polymer Laboratories Dynamic Mechanical Thermal Analyzer (DMTA). The measurements were performed on the siloxanfe-modified epoxies over a temperature range of — 150° to 200 °C at a heating rate of 5 °C per minute and a frequency of 1 Hz. The sample dimensions were the same as those used for flexural modulus test specimens. 

TABLE 7.29 Flexural modulus test results (center-point load) with a Trex and GeoDeck samples and PTL... 

TABLE 7.31 Flexural modulus test results (third-point load) for Trex composite deck board... 

Table 7.37 shows lower values for flexural modulus determined by using 3-pt load compared to 4-pt load. On average, the difference is 9 + 7% in favor of third-point load compared to center-point load in terms of flexural modulus test values. The difference is very close to that (9 + 3%) for flexural strength values (see above). 

When experiments are necessary to determine mechanical properties, the tests should be designed and conducted according to ASTM standards. ASTM is an abbreviation for the American Society for the Testing of Materials. For example, the DMA test above is compared with the ASTM D.790 flexural modulus test in Sepe. °... 

Flexural modulus is the force required to deform a material in the elastic bending region. It is essentially a way to characterize stiffness. Urethane elastomers and rigid foams are usually tested in flexural mode via three-point bending and tite flexural (or flex ) modulus is obtained from the initial, linear portion of the resultant stress-strain curve. 

Elastomer samples are cast in molds, the size and shape of which depend on its purpose. Samples for physical properties can be produced using a custom-made book mold designed to create a thin sheet (0.1 in.) containing premolded test parts, such as those for die-C tear, flexural modulus, and so on. Alternatively, a flat plaque mold may be used to create a 6 x 6 x 0.1-in. sheet from which may be cut samples for testing. Thicker samples for hardness measurements may... 

Compare flexural and tensile modulus testing methods. Why is it reasonable to say that both methods describe the rigidity of a material ... 

Figure 5.75 Effect of gas cell size on the specific flexural modulus of 6-mm-thick polypropylene structural foam. Samples were tested at 23°C with and without their outer skins. Reprinted, by permission, from P. R. Hornsby, in Two-Phase Polymer Systems, L. A. Utracki, ed., p. 115. Copyright 1991 by Carl Hanser Verlag.

Tensile moduli were measured from standard dog-bone samples (2.0 mm thickness, 4.7 mm width, and 22.0 mm gauge length) in a Model 1122 Instron. Flexural modulus was determined using a testing apparatus which consists of two aluminium/steel pieces attached to the Instron which is fitted with a tensile load cell. This device effectively performs an inverted three-point bend the two side bars remain stationary above the sample as the central bar below the sample moves upward. Flexural samples measured ca. 52.0 x 1.7 x 13.1 mm and were tested using a 25.4 mm span (distance between the two side bars). Crosshead speed (CHS) for both flexural and tensile testing was 1.0 mm/min. 

Flexural Properties. Both flexural modulus and flexural strength values were obtained. These values were measured at 23 °C and also over a range of temperatures for the MBAS polymer (see Figure 4). In the flexural tests, a molded bar is tested as a simple beam, the bar resting on two supports, and the load is applied midway between. The test is continued until rupture or 5% strain, whichever occurs first. The test fixture is mounted in a universal tester, and the tester is placed in an appropriate temperature environment. 

Flexural modulus The ratio, within the elastic limit, of the applied stress on a test specimen in flexure to the corresponding strain of the specimen. 

Tensile strength and flexural modulus are generally increased and ultimate elongation is reduced in proportion to the amount of filler, when tested at room temperature. The reverse is generally true when the cured epoxy is tested at elevated temperatures. Impact strength is generally adversely affected by particulate fillers. 

This action eliminates the need for a costly mechanical roughening process that most other materials require. The depositing of a metal surface on plastic parts can increase environmental resistance of the part, also its mechanical properties and appearance. As an example a plated ABS part (total thickness of plate 0.015 in.) exhibited a 16% increase in tensile strength, a 100% increase in tensile modulus, a 200% increase in flexural modulus, a 30% increase in Izod impact strength, and a 12% increase in deflection temperature. Tests on outdoor aged samples showed complete retention of physical properties after six months. 

Mechanical Characterization of Sulfur-Asphalt. The serviceable life of a pavement comes to an end when the distress it suffers from traffic and climatic stresses reduces significantly either the structural capacity or riding quality of the pavement below an acceptable minimum. Consequently, the material properties of most interest to pavement designers are those which permit the prediction of the various forms of distress—resilient modulus, fatigue, creep, time-temperature shift, rutting parameters, and thermal coefficient of expansion. These material properties are determined from resilient modulus tests, flexure fatigue tests, creep tests, permanent deformation tests, and thermal expansion tests. 

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. 

ASTM D 1565, a specification, outlines a test method for dynamic flexing of flexible vinyl cellular materials. This test uses a flexing machine which oscillates at 1 Hz. A minimum of 250,000 flexes are applied. After alternate compression and relaxation the effect on the structure and thickness of the foam is observed. The percentage loss of thickness is reported. Flexural modulus of microcellular urethane is described in ASTM D 3489. This method uses the general procedure in ASTM D 790, Method I. ASTM D 3768 outlines a procedure for determining flexural recovery of microcellular urethanes. The method is used to indicate the ability of a material to recover after a 180° bend around a 12.7-mm (0.5 in.) diameter mandrel at room temperature. 

Following is a list of the kinds of operations performed drying the materials for at least 4 hours at 160°C in a dehumidyfying, recirculating oven injection molding in an Engel machine (barrel temperatures 274-288°C, mold temperature 52°C, overall cycle time 1 min.) mechanical testing (flexural modulus... 

Flexural strength Young s modulus in flexure 5.4 Flexural strength test ... 

Elongation and flexural modulus were measured on an Instron tester model number 1125 according to ASTM D-638 and ASTM D-790 tests respectively. 

For the three-point bending test of the sixth plys laminate panels, the flexural strength of the PTFE / FP composite was about 2.9 times higher than that of the PTFE composite. Moreover, the flexural modulus of the PTFE / FP... 

Table III shows the flexural properties of RX-PTFE composite with an EB dose of 500 kGy and SX-PTFE composite (fluorinated-pitch 1.8 wt% additive) with an EB dose of 500 kGy. For the three-point bending test of the sixth plys laminate panels, the flexural strength of SX-PTFE composite was about 1.1 times higher than that of the RX-PTFE composite. The flexural modulus of SX-PTFE composite was about 1.3 times higher than that of RX-PTFE composite. It was found that the flexural properties of SX-PTFE were improved, compared with RX-PTFE composite.

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