Test method plastic selection

This volume provides an overview of polymer characterization test methods. The methods and instrumentation described represent modern analytical techniques useful to researchers, product development specialists, and quality control experts in polymer synthesis and manufacturing. Engineers, polymer scientists and technicians will find this volume useful in selecting approaches and techniques applicable to characterizing molecular, compositional, rheological, and thermodynamic properties of elastomers and plastics. 

The strength properties more often specified for plastics materials are (1) tensile strength and elongation, (2) flexural strength, (3) Izod and Gardner impact, and (4) heat deflection temperature under load. Our purpose here is not to describe each test in detail but to point out some of the known effects that colorants and other formulation ingredients can have on these properties. Table 22.1 lists the ISO and ASTM test methods for most of the physical properties, and ref. 1 (pp. 7-112) describes each of the methods in detail. Table 22.2 lists typical values of the above cite four properties for selected thermoplastics. 

Materials and articles in contact with foodsmffs - Plastics - Part 1 Guide to the selection of conditions and test methods for overall migration... 

General information about how to determine specific migration is available in CEN document EN 13130-1 2004 Materials and articles in contact with foodstuffs - Plastics substances subject to limitation - Part 1 Guide to test methods for the specific migration of substances from plastics to foods and food simulants and the determination of substances in plastics and the selection of conditions of exposure to food simulants . CEN has also established methods for the determination of some specific migration. Table 5.4 is a list of components for which CEN methods are established. Another source of methods for the determination of specific migration can be found at http // cpf.jrc.it/smt/. At this website of the Joint Research Centre methods are collected and made public online. A summary of the methods available at the website of JRC is given in Table 5.5. 

Materials and articles in contact with foodstuffs - Plastics substances subject to limitation - Part 1 Guide to test methods for the specific migration of substances from plastics to foods and food simulants and the determination of substances in plastics and the selection of conditions of exposure to food simulants... 

Factors are discussed which need to be taken into account when evaluating and designing new biocides for use in plastics formulations. In addition to establishing compatibility with the polymer matrix, the antiniicrobial efficacy has to be tested. The selection of a suitable test method is discussed, together with advantages and disadvantages of traditional test methods. An alternative method based on a modified version of the Film Adherence Method for the evaluation of biocidal performance is presented, which is claimed to be more representative of the end use conditions. 

An important facet of materials development and proper materials selection is testing and standardization. The latter part of this chapter is therefore devoted to this aspect. It presents schematically (in simplified form) a number of standard test methods for plastics, highlighting the principles of the tests and the properties measured by them. 

Water-Vapor Transmission. Primary Film Test Method ASTM E96. The primary test method for the determination of water-vapor transmission through plastics less than 32 mm thick is ASTM E96. (See Fig. 4.) There are two basic methods the Desiccant Method and the Water Method. Agreement between the two methods should not be expected. The method selected should be the one which most nearly approaches the conditions of use. 

Chapter 1 has been updated to provide background to polymer chemistry and plastic formulations. It is an introductory chapter that summarizes the chemistry of making polymers, the formulation of plastics, testing and test methods, and plastic selection. 

A wide range of plastics test methods are available and routinely used to characterize plastics and rubber. Even a basic introduction to the common tests used is beyond the scope of this chapter. The following introductory discussion is on several selected test methods that will allow the reader to better understand the test data presented in other chapters. With most of these tests, there are an extensive theoretical foundation and numerous practical details on how to carry them out as well as the relevant standards that have been left out. With most tests described here, the experience of the operator in sample preparation, carrying out the tests, and analysis of data is critical to obtain rqtroducible results. 

The process of selection between different plastics can be quite bewildering. Copious information on materials is available from the manufacturers, but traditionally this tends to play down any reference to the defects, and to omit any meaningful comparison with alternative plastics. Nowadays there is a proliferation of databases, offering a facility for computerized selection from an impressive list of materials. Data have been compiled over a very wide range of properties, often with an unbiased presentation and uniform test methods and units. With such a huge bank of data now available, the problem is frequently reduced to being one of deciding which of the abundant properties really matter for the component in hand. 

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