Testing of Polymeric Materials

Lack of standards in testing for refractories becomes apparent when one realizes that factors such as sample size and geometry, state of stress in the lining, thermal gradient, thermal cycling and duration are difficult to scale down to a laboratory scale to simulate service conditions. Accelerated tests involving severe conditions do not always conform to realistic conditions and may lead to unrealistic results. 

Crescent and Rigaud43 classified over 100 different experimental arrangements in 12 categories as follows  

Pill test Drip test Basin test 

Crucible test Cmcible test Horizontal rotary test 

Cone test Finger test Vertical rotary test 

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Cayard. M. (1990). Fracture Toughness Testing of Polymeric Materials." Ph.D. thesis. Texas A M University. 

Stress-Strain 335 20.4 Biocompatibility Testing of Polymeric Materials 341... 

ASTMF732-00(2011) Standard Test Method for Wear Testing of Polymeric Materials for Use in Total Joint Prostheses. 

ASTM F732-00. Standard test method for wear testing of polymeric materials used in total joint prostheses. ASTM Int 2006. West Conshohocken, PA. 

Fig. 1. Schematic of common specimen geometries used in fatigue testing of polymeric materials, (a) Tensile test specimen, (b) Flexural test specimen.

Cheremisinoff, N. P., Product Design and Testing of Polymeric Materials , Dekker, New York, 1990. The book reviews test methods and gives an evaluation of the physical and processing performance properties of polymeric materials. 

The paper discusses the application of dynamic indentation method and apparatus for the evaluation of viscoelastic properties of polymeric materials. The three-element model of viscoelastic material has been used to calculate the rigidity and the viscosity. Using a measurements of the indentation as a function of a current velocity change on impact with the material under test, the contact force and the displacement diagrams as a function of time are plotted. Experimental results of the testing of polyvinyl chloride cable coating by dynamic indentation method and data of the static tensile test are presented. 

Plastics testing encompasses the entire range of polymeric material characterizations, from chemical stmcture to material response to environmental effects. Whether the analysis or property testing is for quaUty control of a specific lot of plastic or for the determination of the material s response to long-term stress, a variety of test techniques is available for the researcher. 

When we consider the mechanical properties of polymeric materials, and in particular when we design methods of testing them, the parameters most generally considered are stress, strain, and Young s modulus. Stress is defined as the force applied per unit cross sectional area, and has the basic dimensions of N m in SI units. These units are alternatively combined into the derived unit of Pascals (abbreviated Pa). In practice they are extremely small, so that real materials need to be tested with a very large number of Pa... 

This second group of tests is designed to measure the mechanical response of a substance to applied vibrational loads or strains. Both temperature and frequency can be varied, and thus contribute to the information that these tests can provide. There are a number of such tests, of which the major ones are probably the torsion pendulum and dynamic mechanical thermal analysis (DMTA). The underlying principles of these dynamic tests have been covered earlier. Such tests are used as relatively rapid methods of characterisation and evaluation of viscoelastic polymers, including the measurement of T, the study of the curing characteristics of thermosets, and the study of polymer blends and their compatibility. They can be used in essentially non-destructive modes and, unlike the majority of measurements made in non-dynamic tests, they yield data on continuous properties of polymeric materials, rather than discontinuous ones, as are any of the types of strength which are measured routinely. 

Calmon-Deeriaud, A. Bellon-Maurel, V, Silvestre, K Standard Methods for Testing the Aerobic Biodegradation of Polymeric Materials, Vol 135, pp. 207-226. 

Publication NMAB 318-2. Fire Safety Aspects of Polymeric Materials, Vol. 2 - Test Methods, Specifications and Standards National Academy of Sciences Washington, D. C., Technomic Publishing Co., 1979. 

Zee, M.E. van der, Stoutjesdijk, J.H., Fell, H. and Feijen, J. (1998b). Relevance of aquatic biodegradation tests for predicting degradation of polymeric materials during biological waste treatment. Chemosphere, 36(3), 461 73. 

The frequency of failure (breakdown) of polymeric materials has decreased and will continue to decrease as polymer scientists and technologists recognize the importance of significant tests. In addition to knowing the glass transition temperature Tg and the melting point Tm, scientists must know the results of many other laboratory tests before a polymer can be recommended for a specific application. 

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