Cone test piece

A SERC project (1982-1983) [1,2] produced a new arrow-head test piece that allows the benefits of the cone test piece with no tip sensitivity and the added benefit of the ability to calculate the fracture energy of the bond. The failure generated with this... 

An instrument for measuring the resilience of rubber by dropping a flattened steel cone vertically on the test piece and measuring the rebound. 

A "tension" method using conical metal end pieces is standardised in ISO 460011. BS 903 Part A4012 is identical and ASTM D429, Method C3 is very similar. The test piece diameter is 25 mm and the cone angle 45° but the distance between the tips of the cones is 12 1 mm in ISO and 11.5 1.2 mm in ASTM. An earlier draft of ISO 5600 had the tolerance as 0.1 mm which perhaps implies that this dimension is critical. The grip separation rate is 50 mm/min (or 0.83 mm/s in ASTM) and the result is simply expressed as the maximum force recorded. 

The advantages of cone penetration include the simplicity of the test that the test piece can be used without any previous deformation (which would affect the value of cry) and that the deformation time (of the order of a second) is about the same as during the spreading of margarine. Altogether, the test results correlate well with the subjectively evaluated spreadability. 

The stress distribution is not even, with this test piece, and the action is not pure tension but involves peel and shear forces. The test was investigated by Painter [11] who showed that the stress is concentrated at the tips of the cones. He found that failure occurred at the interface rather than in the rubber, and the measured strengths were lower than with a plain disc test piece of similar diameter, more in line with the results of peel tests. It is probable that the result is sensitive to geometry, particularly the cone... 

The energy absorbed when an object strikes a surface is related to the hardness of the surface the harder the surface, the less the energy absorbed, and the greater the rebound height of the object after impact. Several methods have been developed to measure hardness in this way. The most common method uses a Shore scleroscope, in which the hardness is determined fi om the rebound height after the impact of a diamond cone dropped onto the surface of the test piece. Typical values of Scleroscope hardness together with the Rockwell M values (in parentheses) for some common plastics are as follows PMMA 99 (M 102), LDPE 45 (M 25), polystyrene 70 (M 83), and PVC 75 (M 60). 

Zinc borate gave good performance as a smoke suppressant in the cone calorimeter, but was not as effective as either ZHS or AOM in reducing rates of heat release. Also it had no effect on time to ignition. It was not found to affect the heat stability of rigid PVC, unless used in combination with ATH. The grade of zinc borate used gave a reduction in whiteness of the test pieces and a reduction in impact of 7 kJ/m. ... 

In this test, a 25-nun diameter cylinder of rubber is moulded around two cone-shaped test pieces such that the tips of the test pieces are separated by 10 mm (ASTM D 429, Method C). It has the distinct advantage that the shape of the test piece tends to concentrate the stress towards the rubber-substrate interface. Results are sensitive to the tip radius of the cone, which must be carefully controlled. 

The arrowhead test was suggested by Aubrey et al as incorporating some of the advantages of the cone while being easier to prepare. The test piece consists of a flat arrowhead. 

Test Cone. A test-piece cut or moulded from a sample of refractory material that is to be tested for refractoriness or P.C.E. (q.v.). The shape is that of a pyramid on a triangular base the dimensions vary according to which national specification is being followed. Tetracalcium Aluminoferrite. See brownmillerite. 

In each experiment with the cone calorimeter one piece of sample. 20 cm x 20 cm. was tested. During the test period three pieces of each type of sample were tested. The results presented in Table IV are therefore the average integrated amount of gases generated during sets of three experiments. 

Dissolve 9 3 S of aniline in 30 cc of cone, hydrochloric acid and 100 cc of water. Then pieces of ice are added to the solution to reduce the temperature to 0°C. Prepare sodium nitrite solution by adding 7 2 g of sodium nitrite to 35 cc of water. Add this solution to the aniline solution slowly, and diazotization occurs. Test the solution with potassium iodide starch papers, to avoid excess of sodium nitrite solution. The point is determined by the colour change of the test paper to a slight blue. Add pieces of ice to the solution during the diazotization to keep the temperature at about 5 C. On the other hand, dissolve 15 g of sodium hyroxide in 200 cc of water and then dissolve g of fi naphthol in this... 

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