Mechanical properties ASTM standard

For physical, thermal, electrical, and mechanical properties, ASTM test methods are employed (28). Flammability ratings are often based on Underwriters Laboratories (UL) standards (29). UL flammabiUty ratings given ia this article are aot iateaded to reflect the hazards preseated by the resias uader use coaditioas. Typical properties are givea ia Table 3. More details and additional properties are given ia Refereaces 5 and 31—33. 

Dynamic techniques are used to determine storage and loss moduli, G and G respectively, and the loss tangent, tan 5. Some instmments are sensitive enough for the study of Hquids and can be used to measure the dynamic viscosity T 7 Measurements are made as a function of temperature, time, or frequency, and results can be used to determine transitions and chemical reactions as well as the properties noted above. Dynamic mechanical techniques for sohds can be grouped into three main areas free vibration, resonance-forced vibrations, and nonresonance-forced vibrations. Dynamic techniques have been described in detail (242,251,255,266,269—279). A number of instmments are Hsted in Table 8. Related ASTM standards are Hsted in Table 9. 

Because the mechanical properties of hydrophilic fibers are critically dependent on moisture regain, it is vital that such fibers be tested under constant conditions of temperature and humidity. Standard conditions used in the textile industry are 65% relative humidity and 21°C (1,2,21,96). ASTM D1909, D2118, and D2720 Hst accepted commercial moisture regain values used in the buying and selling of fibers. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

The American Society for Testing and Materials (ASTM) F4 Committee on Medical Materials and Devices has developed specifications for chemical composition, mechanical properties, and other factors. Standard test methods also are available from ASTM, 1916 Race Street, Philadelphia. The quaHty of castings is important for dental implants, and standards to define this would be useful. 

Determination of die mechanical properties of a cured polymer serves to characterize its macroscopic (bulk) features such as flexibility and hardness. Using standardized methods of the American Society for Testing and Materials (ASTM) and die International Standards Organization (ISO) allows direct comparison to otiier materials. The vast majority of polyurethane research and development is conducted in industry where mechanical properties are of vital importance because tins information is used to design, evaluate, and market products. General test categories are presented here with a few illustrative examples. 

When water is used as the immersion liquid, the test is essentially the ASTM Standard Test Method (D570) for Water Absorption of Plastics.( ) Determinations of the relative rate of water absorption are important in evaluating the effects of moisture exposure on such properties as mechanical strength, electrical resistivity, dielectric... 

The mechanical properties of tyrosine-derived poly(iminocarbon-ates) were investigated using the procedures described in ASTM standard D882-83 (Table 2). Solvent-cast, thin polymer films were prepared, cut into the required shape, and tested in an Instron stress strain tester. Since the films were unoriented, noncrystalUne samples, the results are representative of the bulk properties of the polymers. In order to put these results into perspective, several commercial polymers were tested under identical conditions. In addition, some literature values were included in Table 2. 

Mechanical Properties. The mechanical properties of thin, solvent-cast polymer films were measured on an Instron Tensile Tester according to ASTM standard D882-83. In all cases, tensile values were calculated from the average of at least four measurements obtained from four separate specimens per polymer sample. 

Besides the ASTM standard tests, a number of general reference books have been published on testing and on the mechanical properties of polymers and viscoelastic materials (2-7). Unfortunately, a great variety of units are used in reporting values of mechanical tests. Stresses, moduli of elasticity, and other properties are given in such units as MK.S (SI), cgs, and English units. A table of conversion factors is given in Appendix II. 

Despite the fact that inorganic membranes are, in general, more stable mechanically than organic membranes, available mechanical properties data for commercial inorganic membranes are sketchy and these are not yet standardized for comparing various membranes. It appears that the methods used for obtaining various mechanical strength data are based on those for solid (nonporous) bodies and most of them arc listed as ASTM procedures. 

ASTM D 4065-95, Standard Practice for Determining and Reporting Dynamic Mechanical Properties of Plastics, ASTM, West Conshohocken, PA, 1997. 

The study of the mechanical properties of a food is important for determining its strength, texture, and deformation characteristics. The geometry, size, and shape of a sample should conform to standards such as those set by the American Society for Testing and Materials (ASTM), or should meet assumptions for use in mechanical tests for formula development (Mohsenin,, 1970). 

ASTM (1998), Annual Book ofASTM Standards, ASTM Method D 790-97, American Society for Testing and Materials, Committee D20 on Plastics, Subcommittee D20.10 on Mechanical Properties, West Conshohocken, PA. 

The American Society for Testing and Materials (ASTM) provides standards, compatibility testing, and tests for mechanical properties, recommended practices and procedures as well as codes for polymeric materials. The various industry codes and standards are summarized in Table 4.95. 

Most mechanical properties reported in the United States are done according to standards described by the American Society of Testing and Materials (ASTM). The standard method for testing small, clear specimens of timber (ASTM D143) calls for the test to be conducted at 65% RH. Control specimens have a moisture content of approximately 9% (Table 3), whereas specimens reacted with acetic anhydride or formaldehyde have a moisture content of only about 4% and specimens reacted with butylene oxide 6%. This means that the standard test is run on specimens of different moisture contents. Because of the great effect of moisture content on mechanical properties (Table 1), it is misleading or even invalid, to compare strength properties of control and modified wood since they were tested at different moisture levels. 

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%. 

Tensile properties are one of the most important single indications of the strength of a material. Mechanical properties of polymeric materials are often measured using standard test sample configurations. In these studies, a tensile dumbbell-shaped test specimen which conforms to ASTM D638 was used for all measurements. 

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