Mechanical tests tensile modulus

To assess the thermal stabihty of candidate polymeric absorber materials experiencing elevated temperatures associated with glazed collectors, mechanical propsties (tensile modulus and strength, and strain at break) arc measured as a function of time of thermal exposure to dry air and to heated deionized water. Samples are prqjared and tested as po- ASTM D638. Based on the cMculated sovice tempaature distribution, samples were tested for wet exposure at 60X 75X and 90 C. Measurements were made after 1, 3, and 6 months of exposure. 

The mechanical properties were obtained using a tensile machine at room temperature and for a strain rate of 1000%/h. Each reported value of the modulus was an average of five tests. The tensile modulus Et was taken as the slope of the initial straight line portion of the stress-strain curve. 

Characterization of Hydrogel Films. Mechanical testing was conducted in buffered saline on an Instron instrument, according to the modified ASTM D-1708 (tensile) and D-1938 (tear) and were reported in g/mm2 for modulus and g/mm for tear strength. The water contents and the amount of extractables were measured gravimetr ica1ly. 

Most physical tests involve nondestructive evaluations. For our purposes, three types of mechanical stress measures (Figure 14.7) will be considered. The ratio of stress to strain is called Young s modulus. This ratio is also called the modulus of elasticity and tensile modulus. It is calculated by dividing the stress by the strain ... 

As the previous sections have shown, there are a large number of low temperature tests in existence. Even when ad hoc bending tests are disregarded, together with the use of the normal range of physical tests, such as tensile modulus and resilience, and the automation of a mechanical test by thermal analysis, there remain several types of specially developed low temperature tests. The various tests do not all have equal relevance to a given product. A test, or tests, should wherever possible, be chosen to provide the information most relevant to the particular application, but for many quality control purposes a test is used simply as a general indication of low temperature behaviour. Whatever the relative merits of the different methods in any situation, the question of correlation between the methods is frequently asked. 

Dynamic-Mechanical Measurement. This is a very sensitive tool and has been used intensively by Nielsen (17) and by Takayanagi (18). When the damping curves from a torsion pendulum test are obtained for the parent components and for the polyblend and die results are compared, a compatible polyblend will show a damping maximum between those of the parent polymers whereas the incompatible polyblend gives two damping maxima at temperatures corresponding to those of the parent components. Dynamic mechanical measurement can also give information on the moduli of the parent polymer and the polyblend. It can be shear modulus or tensile modulus. If the modulus-temperature curve of a polyblend locates between those of the two parent polymers, the polyblend is compatible. If the modulus-temperature curve shows multiple transitions, the polyblend is incompatible. 

In the case of siloxane elastomers, the testing of mechanical properties is of particular importance. Elongation or tensile measurements are used almost to the exclusion of other types of mechanical tests, probably because of their simplicity. In this way, structural information is obtained about the networks, such as their degrees of cross-linking.92 Measurements of the ultimate strength (modulus at rupture), and the maximum... 

Simple continuum mechanical treatment of the behavior of uniform materials (isotropic) that are tested by pulling the ends of a long thin specimen in tension (uniaxial tension) leads to the following relationship between the shear modulus G, and E, the tensile modulus, where v is Poisson s ratio. 

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. 

The main experimental methodology used is to directly characterize the tensile properties of CNTs/polymer composites by conventional pull tests (e.g. with Instron tensile testers). Similarly, dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) were also applied to investigate the tensile strength and tensile modulus. With these tensile tests, the ultimate tensile strength, tensile modulus and elongation to break of composites can be determined from the tensile strain-stress curve. 

Mechanical Properties. Dynamic mechanical properties were determined both in torsion and tension. For torsional modulus measurements, a rectangular sample with dimensions of 45 by 12.5 mm was cut from the extruded sheet. Then the sample was mounted on the Rheometrics Mechanical Spectrometer (RMS 800) using the solid fixtures. The frequency of oscillation was 10 rad/sec and the strain was 0.1% for most samples. The auto tension mode was used to keep a small amount of tension on the sample during heating. In the temperature sweep experiments the temperature was raised at a rate of 5°C to 8°C per minute until the modulus of a given sample dropped remarkably. The elastic component of the torsional modulus, G, of the samples was measured as a function of temperature. For the dynamic tensile modulus measurements a Rheometrics Solid Analyzer (RSA II) was used. The frequency used was 10 Hz and the strain was 0.5 % for all tests. 

Mechanical Properties. The tensile properties of the cast specimens were determined using dog-bone-shaped specimens following ASTM D-638, at a crosshead speed of 0.2 in./min on a tensile testing machine (Instron 4505). The strain to failure of the specimens was measured using an exten-someter. The tensile strength and tensile modulus were also determined. 

Tensile testing is a widely used mechanical test from which not only tensile strength but elongation and modulus can be obtained. In the test a waisted or dumb-bell shaped sample is measured in the waisted region and then firmly gripped in machine jaws which draw away at a constant speed. 

PP/Montmorillonite (MMT) nanoclay based composite was prepared by melt compounding with MA-g-PP in a twin-screw extmder and an internal mixer. Test specimens were prepared by compression molding. Mechanical properties such as tensile modulus, tensile strengfli and maximum percentage strain were measured. The clay dispersion was investigated using WAXD and SEM. 

As mentioned earlier, the DMTA technique measures molecular motion in adhesives, and not heat changes as with DSC. Many adhesives exhibit time-dependent, reversible viscoelastic properties in deformation. Hence a viscoelactic material can be characterized by measuring its elastic modulus as a function of temperature. The modulus depends both on the method and the time of measurement. Dynamic mechanical tests are characterized by application of a small stress in a time-varying periodic or sinusoidal fashion. For viscoelastic materials when a sinusoidal deformation is applied, the stress is not in phase with displacement. A complex tensile modulus E ) or shear modulus (G ) can be obtained ... 

The test data are shown in Table III. The mechanical tests were performed at room and liquid nitrogen temperatures, with no apparent differences for the results at the lower temperature. The tensile strength on the composite was within 10% of the predicted value and the tensile modulus was within 20%, as calculated by the rule of mixtures, i.e., 96 vs. 117 GPa. The density of the composite was measured at 5.34 g/cm. ... 

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