Mechanical properties determination

Step 2. After a contact time t, the material is fractured or fatigued and the mechanical properties determined. The measured properties will be a function of the test configuration, rate of testing, temperature, etc., and include the critical strain energy release rate Gic, the critical stress intensity factor K[c, the critical... 

The testing of materials can be based on whether the tested material is chemically changed or is left unchanged. Nondestructive tests are those that result in no chemical change in the material which may include many electrical property determinations, most spectro-analyses, simple phase change tests (Tg and Tm), density, color, and most mechanical property determinations. Destructive tests result in a change in the chemical structure of at least a... 

We turn our attention now to some practical aspects of mechanical property determinations. The important quantities such as modulus, strength, and ductility are typically summarized in graphical form on a stress-strain diagram. The details of how the experiment is performed and how the stress-strain diagram is generated are described for some common types of applied forces below. 

In contrast to soft biologies, whose mechanical properties primarily depend upon the orientation of collagen fibers, the mechanical properties of mineralized tissues, or hard biologies, are more complicated. Factors such as density, mineral content, fat content, water content, and sample preservation and preparation play important roles in mechanical property determination. Specimen orientation also plays a key role, since most hard biologies such as bone are composite structures. For the most part, we will concentrate on the average properties of these materials and will relate these values to those of important, man-made replacement materials. 

Wood has been reacted with propylene oxide and mechanical properties determined [25]. Maple specimens were reacted to 20-22 WPG and subjected to standard ASTM tests. The following is a summary of the results comparing propylene oxide-modified specimens to controls. MOE was decreased by 14%, MOR decreased by 17%, fiber stress at proportional limit reduced by 9%, maximum crushing strength decreased by 10%, radial hardness increased by 5%, tangential and longitudinal hardness remained unchanged, and the diffusion coefficient increased by 29%. 

The dynamic mechanical properties are of direct relevance to a range of unique polymer applications concerned with the isolation of vibrations or dissipation of vibrational energy in engineering components (e.g. noise reduction). Applications concerned with creep and stress relaxation under static loading conditions in engineering components can be approximately estimated from the dynamic mechanical properties determined over wide ranges of frequency and temperature. 

International Organizationfor Standardization (ISO) (1999), ISO 13997Protective Clothing - Mechanical properties. Determination of Resistance to Cutting by Sharp Object, Geneve, Switzerland. 

ASTM D 4065-01, Standard Practice for Plastics Dynamic Mechanical Properties Determination and Report of Procedures ... 

Standard practice for plastics - Dynamic mechanical properties Determination and report of procedures... 

British Standards Institution. BS EN ISO 13997 1999, Protective clothing - mechanical properties - determination of resistance to cutting by sharp objects. London BSI 1999. 

As discussed, in Section 6.14.7.3, increasing interest has been devoted to amphiphilic materials containing PEO. The importance of controlling the structural parameters has been pointed out. This controlled tailoring of hydrophilidty, crystallinity, and mechanical properties determines the ultimate biological application of the materials. Breitenkamp investigated the ROMP... 

PC/LCP/ABS DSC/ C NMR/SEM/rheology/mechanical properties/determination of optimum transreaction vs. properties/phosphoms-containing LCP Chen et al. 2009... 

Figure 17.19 shows typical thermal expansion behavior of a PP/PP-g-MA/MMT/ elastomer nanocomposite from the first and second heating the thermal expansion is a nonlinear function of temperature when viewed over the wide range of —40 °C to 125 °C hence, CTE is reported in the temperature range of 0-30 °C so it can be related to the mechanical properties determined at room temperature (Lee et al. 2006a). For both extruder-made and reactor-made TPO nanocomposites, the CTE along the ED and the TD decreases, whereas CTE along the normal direction (ND) increases as the MMT content is increased. The increase in CTE in the ND is... 

The final mechanical properties determined on different completely postcured PU sheets after more than two months revealed the interesting fact that even if these samples were made and stored simultaneously under the same conditions, the final mechanical properties were not totally similar (Table 4.30). 

MPa) and other samples are into the rocks class with very high strength (50-160 MPa). The results of physical and mechanical properties determinations are given in Table 2. 

A series of mechanical property determinations was made to determine the reproducibility and spread of the tests results when materials of various levels of crystallinity were tested at cryogenic temperatures. It was found that there was a definite correlation between the crystallinity (as determined by the hardness test) of the samples and their low-temperature mechanical properties. As an example, samples of relatively low crystallinity were much stronger and more ductile at cryogenic temperatures than the highly crystalline samples. As a result of these determinations, it was found that a reasonably accurate set of low-temperature mechanical properties could be assigned to any fluoroplastic by performing this simple non-destructive room temperature hardness test. 

Dynamic mechanical properties, determined under tension, were complex [21]. The major features for PCL were a small loss of elastic modulus associated with the P-relaxation, a decrease in modulus (from 20 MPa to about 6 MPa) associated with the a-relaxation (from about -60 °C to -20 °C), a continuing loss in modulus with increasing temperature, to about 4 MPa and a major loss in modulus associated with T j from about 50 °C. PC showed a small loss in modulus associated with its P-relaxation at about -75 °C and a major loss of modulus, from about 15 MPa, associated with the a-relaxation at about 150 °C [21]. 

The structural changes at the level of crystalline and amorphous phases have been confirmed by the variation of the mechanical properties, determined for the stressed samples in the conditions previously described. As Table 3.104 shows, the effects of fatigue process are clearly evidenced both by the evolution of specific stress, i.e. elasticity, yield, and fracture limit, and the corresponding strains. 

Table 5.3 lists the principal experimental methods used in dynamic mechanical testing. Of the experiments considered below, the thermal scan mode (method 1) is the technique most commonly used by thermal analysts. Here typical applications in quality control or processing look for differences in material batches, thermal history, different grades, reactivity, and other characteristics. The stepped isotherm (or step isothermal) experiment (method 2) is used mainly in studies involving detailed mechanical property determination for structural analysis, vibration damping applications, and for determining time-temperature superposition master curves. Method 3 (fast scan or single isotherm) is application specific. 

Cones, whiskers, and GPC can bridge the nano- and microworlds and may have numerous applications, where sizes between nanotubes and carbon fibers are required. They may also have interesting electronic and mechanical properties determined by their geometry. However, although their structure has been well understood, very little is known about their properties. Properties need to be studied before their wide-scale applications can be explored. 

---