Test method Gardner

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. 

In practice, however, the multiaxial stress applied in a falling dart test without a preferred direction, has to be expected. This is addressed by the Gardner test of ASTM, in which a falling dart strikes centrally on a flat surface (e.g. a circular disk). The results of both test methods are important polymer design considerations. 

ASTM D 4890-88 Standard Test Method for Polyurethane Raw Materials Determination of Gardner and Alpha Color of Polyols, 3 pp (Comm D-20)... 

ASTM D1544 Test Method for Color of Transparent Liquids (Gardner Color Scale)... 

New York. Tatton WH, Drew EW (1964) Industrial paint application. Van Nostrand Co. Inc., Princeton, NJ. Taubes F (1971) Painter s dictionary of materials and methods. The Watson-GuptiU Publications, New York. Sward GG (ed) Paint and Coating Testing Manual (Gardner-Sward Handbook) (1995) MNL 17, 14th edn. ASTM, Conshohocken, PA. 

The major collection of complete test methods for coatings is Physical and Chemical Examination of Paints, Varnishes, Lacquers, and Colors, by Gardner and Sward, Gardner Laboratory, Bethesda, Md. This has gone through many editions. 

Many empirical tests are used to test coatings. In most cases, they are more appropriate for quality control than performance prediction. ASTM tests of importance to the coatings field are in Volumes 06.01, 06.02, and 06.03 Paint—Tests for Formulated Products and Applied Coatings. Many people believe the tests are more precise than they proved to be in ASTM roimd robin tests (40). An excellent reference book is the Paint and Coating Testing Manual (Gardner-Sward Handbook) (41). It gives descriptions of test methods and summaries of each main class of properties. 

ASTM D5420, Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimen by Means of a Striker Impacted by a Falling Weight (Gardner Impact), 2004. 

ASTM D5420, Standard test method for impact resistance for flat rigid plastic specimens by means of striker impacted by a falling weight (Gardner impact), 2004. 

Gardner color scale is made of arbitrary glass standards numbered from 1 to 18. Measurements are made according to standardized method (ASTM D1544-04 (2010) Standard Test Method for Color of Transparent Liquids (Gardner Color Scale)). 

Methods employed to determine the impact resistance of plastics include pendulum methods (Izod, Charpy, tensile impact, falling dart, Gardner, Dynatup, etc.) and instrumented techniques. In the case of the Izod test, what is measured is the energy required to break a test specimen transversely struck (the test can be done either with the specimen notched or unnotched). The tensile impact test has a bar loaded in tension and the striking force tends to elongate the bar (Chapter 5, Impact Strength). 

Gardner, 1. A., and M. Greiner. 2006. Receiver-operator characteristic curves and likelihood ratios Improvements over traditional methods for the evaluation and application of veterinary clinical pathology tests. Veterinary Clinical Pathology 35 8-17. 

Gardner, I. A. and Greiner, M. ( 999) Advanced Methods for Test Validation and Interpretation in Veterinary Medicine. Freee University, Berlin and University of California, Davis, CA (report). 

The method detailed in ASTM D.S420 [87] is somewhat unusual compared to other impact standards in that the test piece, which is placed on a support plate having a circular hole of given size, has a striker resting upon it. and the striker is then impacted by the falling weight. This is the so-called Gardner impact test, and a number of variations in... 

---