Clash-Berg test

FFE-1, the blsphenol A/blsphenol fluorenone copolyester had a Tf (Indicative of glass transition) at 177 C. Polymer FPE-4 could not be molded into a Clash-Berg specimen. Therefore, a filter paper was coated by THF solution of sample FPE-4 and dried. Eight strips were compiled and made into one test specimen and the Clash-Berg test was run. A Tg of 270 C is indicated (Figure 9). This is the same value as that determined by thermal mechanical analysis. 

Clash-Berg test See test, stiSness, Clash-Berg, clasp See packaging clasp. 

Rigidity in torsion Clash Berg, Gehman tests... 

The compounds were mixed on a two-roll mill at 320°F. for 8 minutes, then molded into test plaques at 340°F. and 1500 p.s.i. Samples for mechanical testing, hardness, compatibility, and Clash-Berg temperature were 0.075 inch thick while carbon black volatility and extractions were performed on 0.010 inch films. All testing was in accordance with ASTM specifications, and results are summarized in Tables II through V. 

Creep testing was performed on a Clash-Berg Torsion Stiffness Tester. Silicone oil was used as the heat transfer medium. Temperatures were held constant to within + 1... 

The main torsional test method is the Clash and Berg test standardized in ISO 458. Parts I [156] and 2 [157], which are dual numbered in BS 2782 as Methods 153A [158] and B [159]. ASTM D1043 [160] is technically equivalent to Part 1. 

Clash-Berg point n. The rising temperature at which the apparent modulus of rigidity of a specimen fells to 931 MPa, the end point of flexibility as defined by Clash and Berg in their studies of low-temperature flexibility. In a similar test described in ASTM D 1043, the deciding shear modulus is one-third the C-B value. 

Low-Temperature Flexibility All plastics that are flexible at room temperature become less so as they are chilled, finally becoming brittle at some low temperature. This property is often measured by torsional tests over wide ranges of temperature, from which apparent moduli of elasticity are calculated. See also Brittleness Temperature and Clash-Berg Point. Some relevant ASTM tests are D 1043, D 3295, D 3296, D 3374 (Section 07.02), and D 1055 (Section 09.01). 

Torsional Stiffness - Torsional stiffness tests measure the modulus of rigidity of an elastomer composition over a broad temperature range. Two widely-used tests are ASTM D-1043, which uses the Clash-Berg Tester, and the ASTM D-1053, which uses the Gehman Torsional Stiffness Tester. In both tests, the sample is chilled to a preset temperature, then twisted with a known force. The amount of twist is measured and related to the stiffness (modulus of rigidity) of the sample. The test temperature is then changed and the test is repeated, until a complete curve of stiffness vs. temperature is plotted. The temperature which produces a stiffness of 69 MPa (10000 psi) is sometimes taken as the Stiffness Temperature. 

These tests relate to the temperature-dependence of the properties of a polymeric material. Common tests include softening behaviour (particularly of thermoplastics) and low-temperature flexibility, for example Vicat softening point, heat-deflection temperature and Gehmann, Clash and Berg apparatus testing. 

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