Vulcanized mechanical tests

Most testing of rubber and rubber compounds is conducted to determine processing characteristics or to measure physical properties after vulcanization. Processability of a rubber compound is dependent on the compound s viscosity and elasticity. Generally, the physical properties of vulcanized rubber compounds are measured by static and dynamic mechanical tests designed to simulate the mechanical conditions of finished rubber products. Following are the test procedures and instruments most widely used to measure and evaluate processability and finished properties. 

R. J. Moseley, R. A. Amos and J. R. Scott, Physico-Mechanical Testing of Unvulcanized and Vulcanized Rubbers , MacLaren, London, 1962. 

The results of mechanical tests, presented in Figure 5, show that the tensile strength of vulcanized latex films surpasses considerably that of analogous vulcanized rubbers (30-35 kg/cm ). This fact, already determined repeatedly for other types of rubber, can be explained in terms of the peculiarity of network of latex films distribution. 

Dynamically vulcanized thermoplastic elastomer (TPV)/organoclay nanocomposites based on EPDM/PP containing 2, 4, 6% of organically treated montmorillonite were prepared by using EPDM-g-MA and PP-g-MA as compatibilizer. Dicumylperoxide (DCP) and triallyl cyanurate (TAC) were employed as crosslinking system. X-ray diffraction (XRD) analysis has been performed to evaluate the extent of the intercalation.. In this study, attempts have been made to exclusively reinforce rubber dispersed phase. Rheological behavior and melt viscoelastic properties of the samples such as elastic modulus, and elastic response expressed in terms of relaxation time distribution, H (A), were studied. The results were also supported by differential scanning calorimetry (DSC) and mechanical tests. 

The principal mechanism of reinforcement of tear resistance of vulcanized filled rubber is associated with the phenomenon of knotty tearing. In knotty tearing the tear deviates almost perpendicularly from the intended tear path and the knot looks approximately like a semi-circular arc on the torn test-piece (in the unstrained state) as shown in Figure 5.4. 

The activity of the carbon supports needs to be evaluated for each catalyst material to be tested. An important finding was that metal-free Vulcan XC-72R (i.e., carbon black only) cathodes produced significant currents (Ppeak = 22mWcm and Vqc = 0.88 V with Solvay ADP at 50°C). Carbons reduce O2 primarily through a 2e mechanism at high pH producing hydroperoxide anions (HO2 ), which may form highly reactive hydroxyl radical species. 

Some details of the equipment are illustrated by Fig. 16. The upper die can be raised to separate it from the lower die. A sample of uncured rubber compound can be then introduced and the upper die lowered into place as in the illustration. In this work, the dies were first heated and controlled at an elevated temperature (e.g., 90°C), then the temperature of the dies and sample can then be quite rapidly changed to a desired temperature for testing or for vulcanizing the sample. The sample can be introduced at one temperature, measurements of dynamic mechanical properties (e.g., storage shear modulus G and loss shear modulus G ) can then be made at the same temperature or at another temperature. Then, if desired the sample can be heated to a vulcanization temperature and vulcanized (with the recording of a cure curve, i.e., modulus versus time) and then the temperature can be changed and dynamic mechanical properties can then be measured again. 

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