Composite materials performance test methods

Some rubber compositions, for example those containing reactive chlorine, can promote the surface corrosion of metals in contact with them, and in certain applications this can be sufficient to impair component performance. To guard against the use of such materials, a test method is described in ISO 6505 (BS903. Part A37). The procedure is similar to that for contact stain, in that a. sandwich of rubber and test surface, in this case a specified metal, is stored under load in a temperature-controlled environment for a given period. The measurement is a visual one and includes an indication of the ease of separation of the test rubber and the metal at the conclusion of the test. 

Data for thermal movement of various bitumens and felts and for composite membranes have been given (1). These describe the development of a thermal shock factor based on strength factors and the linear thermal expansion coefficient. Tensile and flexural fatigue tests on roofing membranes were taken at 21 and 18°C, and performance criteria were recommended. A study of four types of fluid-appHed roofing membranes under cycHc conditions showed that they could not withstand movements of <1.0 mm over joiats. The limitations of present test methods for new roofing materials, such as prefabricated polymeric and elastomeric sheets and Hquid-appHed membranes, have also been described (1). For evaluation, both laboratory and field work are needed. 

An extensive survey of accelerated test methods for anticorrosive coating performance which emphasizes the need to develop more meaningful methods of testing has been pubUshed (129). The most powerful tool available is the accumulated material in data banks correlating substrate, composition, apphcation conditions, and specifics of exposure environments with performance. 

Evaluating composite performance requires test methods for mechanical properties of the constituent materials (fibers, tows, filaments, and matrices) as well as the composite materials themselves. The types and quantities of tests to be performed, and the selection of testing parameters, depends on the information desired. For material development, the tests may be much simpler and less numerous than those that would be chosen for design qualification, but may encompass a greater range of test parameters than would be expected in service. In the case of materials development, it is the trends in the data and the mechanisms by which failures occur which are most important, and it is crucial to examine the extremes of behavior. For component design and qualification, it is more important to know the reliability and reproducibility of the material under conditions which resemble the expected service conditions. 

A composite material made of zinc oxide and polyvinyl alcohol was prepared by a sonochemical method [135]. Annealing of the composite under air removed the polymer, leaving porous spheres of ZnO. This change was accompanied by a change in the surface area from 2 to 34 m g k The porous ZnO particles were used as the electrode material for dye-sensitized solar cells (DSSCs). They were tested by forming a film of the doped porous ZnO on a conductive glass support. The performance of the solar cell is reported. 

Calibration refers to the procedures used for correlating test method ontpnt or response to an amount of analyte (concentration or other quantity). The characteristics of a calibration fnnction and justification for a selected calibration model should be demonstrated dnring SLV and ILS stndies. The performance of a calibration technique and the choice of calibration model (e.g., first-order linear, cnrvifinear, or nonlinear mathematical function) are critical for minimizing method bias and optimizing precision. The parameters of the model are nsnally estimated from the responses of known, pnre materials. Calibration errors can result from failure to identify the best calibration model inaccnrate estimates of the parameters of the model errors in the composition of calibration materials or inadeqnately smdied, systematic effects from matrix components. This section focnses on the critical issne of the traceability and supply of materials used for calibration of marine biotoxin methods. 

There are no standard test methods specific for discontinuous fiber (or short fiber) reinforced thermoplastics. It is also not clear whether a geometry-independent fracture parameter can be measured for these nonuniformly inhomogeneous materials. However in spite of these reservations there has been considerable work conducted towards characterizing short fiber composites for fracture toughness using the standard and other procedures outlined in the previous sections. The investigators have recognized that fracture mechanics data provide much more reliable information than the customary alternative tests for material selection and also a service performance indicator for components. 

The introduction of commercial aircraft built with increas-ingly complex composite materials and configurations has led aircraft manufacturers, their suppliers and the Federal Aviation Administration (FAA) to review the test methods used to determine fire safet-y. A particular focus has been placed on reexamining the flammability performance cri-teria established by FAA 14 CFR 25.853, which governs mate-rials used in aircraft interiors. 

In 1999, the Plastic Lumber Trade Association reported that RPL was growing at a 30 percent annual rate. Growth of plastic lumber was been fueled by growing knowledge about performance properties of the material and how they relate to composition, as well as by the develcmment of performance standards such as the standard test methods developed by ASTM. By 2005, nine ASTM test methods for RPL had been established, along with two standards for plastic/fiber composites. However, growth of plastic lum-her has slowed, and the Association has not placed an annual report on their web site since 2002. 

Accelerator mass spectrometry (AMS) is useful to measure extremely low-abundance nuclides (isotope ratio of 10 to 10 relative to its stable isotope), such as Be, C, A1, C1, " Ca, and I, in natural samples. Small amounts of C and T can be measured by AMS on mg size samples of carbon and iodine extracted from 500-ml seawater samples (Povinec et al. 2000). Neutron activation analysis (NAA), radiochemical neutron activation analysis (RNAA), and inductively coupled plasma mass spectrometry (ICP-MS) are useful for the determination of ultra-trace Th and U in geological and cosmochemical samples, and for determination of the concentration of Pu and Pu. Reference marine-biological samples are necessary to test the performance of the analytical methods employed in surveying and monitoring radioactive materials in the sea. An ocean shellfish composite material containing 0.1% w/w Irish Sea mussel, 12% w/w White Sea mussel, and 87.9% w/w Japan Sea oyster has been prepared as the NIST SRM 4358 (The National Institute of Standards and Technology, SRM) in the natural-matrix, environmental-level radioactive SRM series (Altzitzoglou 2000). This NIST SRM 4358 sample will be useful for the determination of the activity of K, Cs, Pb, Ra, Th, and Am. 

In practice, only in very few cases do materials work in tensile mode more often they are subjected to flexure or impact. On the other hand, fiber-reinforced composites are usually applied as laminates with different orientation and alignment of the fibrous reinforcement. That is why the CPC laminates were used to study their flexural stiffness and impact resistance. The flexural tests were performed by the threopoint support test method used by Nunes et al, as shown in Figure 14.6 [74]. The support was mounted in the same Instron machine used for the tensile tests, this time operating in compression mode. Rectangular samples (155 x 100 mm) were cut out from the CPC MFC plates and placed upon the sup-... 

---