Heat buildup

Heat buildup is closely related to resilience and a low tan (8) value. The design of the part is vital to allow heat that is built up to dissipate successfully. Ether-based materials have a lower heat buildup than esters. 

This method measures the heat buildup of a sample inside an insulated wooden box under a 250 W heat lamp. Thermocouples are placed beneath the samples, which are least 3x Bin size. A carbon black reference is also measured. The equilibrium temperature for each is recorded, and the temperature differences above ambient are used to predict theoretical heat buildup of the sample according to Eq. (24.4). The maximum external heat buildup for the black sample (ATc) is 41 °C for vertical orientation and 50 °C for horizontal orientation. The method is defined for PVC but can be applied to other colored objects. While the test does not measure solar reflectance, it does provide useful information on the expected performance of the object in the end application. The practical nature of this test makes it an effective tool for demonstrating the difference between objects colored with and without high-performance pigments. It is important to note that the method clearly states that while the test provides data on relative heat buildup, it cannot predict actual temperatures the object will experience in its service hfe. The ambient conditions of the test are controlled, and the field conditions have numerous factors (incident sunlight angle, weather, insulation) that will affect 

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Permanent set and low hysteresis properties depend on minimizing the viscous or plastic component of modulus. Because cross-linking increases elasticity, a high state of cure typically provides the best compression set and heat buildup properties. 

AH three systems give similar tensile strength, elongation, and hardness properties. Hysteresis (heat buildup) measured by tan 5 shows an advantage for conventional and semi-EV systems and unaged fatigue follows the expected pattern. 

HBU = heat buildup, a measuie of tempeiatuie lise and lesistance to fatigue (ISO 4663/3). 

In the same way that natural mbber is predominandy used in blends, it is also predominandy used in tire manufacture. Its excellent building tack, low heat buildup, low rolling resistance, and good low temperature performance make it the polymer of choice for many parts of tire constmction, for both passenger and tmck vehicles. The effects of radiali2ation and demand for low rolling resistance and good low temperature performance have all tended to benefit natural mbber, especially in tmck tire constmction, as shown in Table 9. 

Car manufacturers and intermediaries offer various forms of rail-car leases, ranging from short-term, full-maintenance rentals to long-term leases requiring outside financing (3). Many chemical shippers have substantial investments or lease commitments in tank cars and similar rail equipment, including cars constmcted of or lined with special materials for particular products. Other cars may be thermally insulated to prevent excessive heat buildup in transit or for protection against fire. 

During some mol ding and extmsion operations, knit line failures, incomplete mold fill, die drag, and excessive heat buildup, ie, scorch, are problems. Many of these problems are reduced or eliminated by the addition of internal lubricants such as low mol wt polyethylene or Vanfre AP-2 Special, a product of R. T. Vanderbilt. 

Natural rubber was the only polymer for elastomer production until the advent of synthetics. Natural rubber, however, continues to maintain its competitive edge due mainly to the gain in properties such as high resilience, low hysteresis, low heat buildup, and excellent tack with mechanical properties achieved through the process of vulcanization [114-115]. The industry is said to be self-sufficient with a good technological base and is expected to compete successfully with synthetics because of the edge in properties mentioned above [116,117]. 

The rate dependence of fatigue strength demands careful consideration of the potential for heat buildup in both the fatigue test and in service. Generally, since the buildup is a function of the viscous component of the material, the materials that tend toward... 

Viscoelastic damping The same approach can be used in designing power transmitting units such as belts. In most applications it is desirable that the belts be elastic and stiff enough to minimize heat buildup and to minimize power loss in the belts. In the case of a driver which might be called noisy in that there are a lot of erratic pulse driven forces present, such as an impulse operated drive, it is desirable to remove this noise by damping out the impulse and get a smooth power curve. 

The key performance properties of conveyor belts, particularly belt cover compounds, are flex resistance, abrasion resistance, and low heat buildup. The effect of l,3-bis(citraconimidomethyl) benzene on these key properties, in addition to cure characteristics and tensile properties, has been evaluated in a typical, NR-based belt cover formulation listed in Table 14.49. 

The essential performance properties for an engine mount are low heat buildup and low dynamic compression set. These have been determined for a typical engine mount compound based on NR, with and without Perkalink 900—Table 14.50. 

FIGURE 14.19 Goodrich flexometer heat buildup at 100°C after 30 min (load 108 N, stroke 4.45 mm, frequency 30 Hz). 

The important vulcanizate properties demanded by this application, low heat buildup, and low dynamic set have been determined in the Goodrich Flexometer test. The compound containing the antireversion agent exhibits a marked decrease in heat buildup and dynamic permanent set (Figures 14.21 and 14.22). 

Perkalink 900 is also active in compounds based on blends of NR with the synthetic elastomers SBR and BR. An evaluation in a tank pad formulation has provided evidence of reduced heat buildup on overcure overcure is a common problem in the manufacture of these relatively bulky components. The control and test formulations, in which two levels of the antireversion agent have been evaluated, are fisted in Table 14.52. Cure characteristics are given in Table 14.53. 

Although httle advantage is observed with regard to vulcanizate physical properties (Table 14.54), a benefit is apparent in terms of reduced heat buildup (Figure 14.23). In addition, the antireversion agent provides greater thermal stability in terms of blow-out resistance... 

Goodrich heat buildup shows some discrimination between the QDI-containmg compounds and the others under both mild and oxidative mixing conditions. Figure 16.4 shows the delta temperature... 

Final Mooney viscosity versus heat buildup 95% CLdf=8... 

FIGURE 16.4 A general trend toward higher heat buildup as a function of lower Mooney viscosity is observed. 

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