Mechanical properties definition

The mechanical properties of rigid foams vary considerably from those of flexible foams. The tests used to characterize these two classes of foams are, therefore, quite different, and the properties of interest from an application standpoint are also quite different. In this discussion the ASTM definition of rigid and flexible foams given earlier is used. 

Inorganic membranes (29,36) are generaUy more stable than their polymeric counterparts. Mechanical property data have not been definitive for good comparisons. IndustriaUy, tube bundle and honeycomb constmctions predominate with surface areas 20 to 200 m. Cross-flow is generaUy the preferred mode of operation. Packing densities are greater than 1000 /m. Porous ceramics, sintered metal, and metal oxides on porous carbon support... 

Mechanical history, heat, and impurities gready affect the mechanical properties. Pure zinc is ductile at room temperature and does not have a definite yield point as do most stmctural metals. Rather, it creeps under sufficient constant load. The impurities of commercial zinc and alloying metals are carefully controlled to achieve the desired mechanical properties. 

The most widely used plasticizers are paraffinic oils. Por appHcations that specify high use temperatures, or for peroxide cures, paraffinic oils of low volatihty are definitely recommended. However, since paraffinic oils exude at low temperatures from EPDM vulcanizates, or from high ethylene EPDMs, they are often blended with naphthenic oils. On the other hand, naphthenic oils interfere with peroxide cures. Aromatic oils reduce the mechanical properties of vulcanizates, and they also interfere with peroxide cures. Therefore, they are not recommended for EPM/EPDM. 

Mechanical Properties. The mechanical properties used for design shall be the minimum values allowed by the applicable material specification or shall be the minimum values determined by the manufacturer in accordance with the test procedures specified in ASTM A370 Methods and Definitions for Mechanical Testing of Steel Products, or by mill certification for mill products. The yield point shall be used in lieu of yield strength for those materials exhibiting a yield point. Yield strength shall be determined at 0.2% offset. 

Whether any of the formulation variables change the mechanical properties significantly upon aging cannot be answered due to the lack of definition of chemical composition parameters as discussed previously... 

The effect of temperature on the mechanical properties has definite place in specification of a material for any particular application. Some materials become dangerously brittle under arctic conditions, and all metals exhibit at elevated temperatures a phenomenon called creep. 

These examples indicate that it is necessary to keep the possible effect of point defects on bulk and mechanical properties in mind. Although less definitive than electronic and optical properties, they may make the difference in the success or failure of device operation. 

CNTs may consist of just one layer (i.e. single-walled carbon nanotubes, SWCNTs), two layers (DWCNTs) or many layers (MWCNTs) and per definition exhibit diameters in the range of 0.7 < d < 2 nm, 1 < d < 3 nm, and 1. 4 < d < 150 nm, respectively. The length of CNTs depends on the synthesis technique used (Section 1.1.4) and can vary from a few microns to a current world record of a few cm [16]. This amounts to aspect ratios (i.e. length/diameter) of up to 107, which are considerably larger than those of high-performance polyethylene (PE, Dyneema). The aspect ratio is a crucial parameter, since it affects, for example, the electrical and mechanical properties of CNT-containing nanocomposites. 

Welding is very difficult for PTFE and definitely alters mechanical properties. 

Definition of Terms Relating to the Non-Ultimate Mechanical Properties of Polymers... 

Definitions of terms relating to the non-ultimate mechanical properties of polymers (lUPAC Recommendations 199 ), Pure Appl. Chem. 70, 701-754 (1998). 

The engineering principles of thermodynamics, kinetics, and transport phenomena, as well as the chemistry and physics of molecnlar strncture, serve as the basis for the remaining topics in this book. In this chapter, we look at what for many applications is the primary materials selection criterion mechanical properties. As in the previous chapter, we focns primarily on the properties of materials, bnt discnss briefly the mechanics, both in the fluid and solid states, that give rise to the properties. There is a great deal of new terminology in this chapter, and it is cumnlative—take time to nnderstand all the definitions before proceeding to the next section. 

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