Ball rebound

Possible Answer Perhaps the gas put in the balloon consists of a collection of small particles that rebound from the wall of the balloon just as billiard balls rebound from the cushions of a billiard table. As the gas particles rebound from the balloon wail, they push on it. When more gas particles are added, the number of such wall collisions per second increases, hence the outward push on the balloon wall increases. The balloon expands. 

This discussion of threshold energy causes us to wonder what energies are possessed by molecules at a given temperature. We have already compared the molecules of a gas with billiard balls rebounding on a billiard table. When billiard balls bounce around, colliding with each other, some of them move rapidly and some slowly. Do molecules behave this way Experiment provides the answer. 

Falling-ball rebound test, 244 Ferrocene-containing polybenzimidazole, 315... 

Another parameter, A, derived from ball-rebound values, has also been used in conjunction with txF and surface area measurements to characterize carbon blacks in terms of vulcanizate properties ... 

High-Resilient Foam (HR Foam). HR foam is characterized by high ball rebound, low hysteresis loss and high sag factor. HR foam can be produced either as slabstock or as molded foam. 

Covers density, indentation-force deflection, compressionforce deflection, constant deflection, compression set, tension, tear resistance, air-flow, resilience (ball rebound), static-force loss at constant deflection, dynamic fatigue, steam autoclave aging, and dry-heat aging. 

The distance between aggregates is a value which correlates with many properties of filled rubber. Figure 7.35 gives an example of the correlation with tanb. " Other applications were made with these properties ball rebound, effect of graphitization on properties of carbon black and parameters of carbon black which characterize structure. 

The ball is released within a vertical clear plastic tube of internal diameter 38 mm so that it falls without rotation. The drop height is 500 mm, and the tube is marked at 25 mm intervals with a full circle. Rebound resilience is reported in percent. For a discu.ssion on ball rebound resilience see Ref. 2. 

Tables 1.38 and 1.39 provide the physical property comparison for the 55 kg/m MDI flexible moulded formulations XXV-XXXIV. The data clearly demonstrates that physical properties are maintained, and in several cases improved, compared to the control formulations, depending on the formulation. For example, the data in Table 1.38 illustrates that all physical properties are matched to the control formulation (XXV) at an index of 105 with the exception of a slightly lower ball rebound for the full non-fugitive catalyst package. At an index of 105, all physical properties for the experimental non-fugitive catalysts formulations were determined to be similar to the control (XXX). When Dabco NE1060/BL-11 is used as a low emission catalyst package (XXXHI), all physical properties at the index of 105 are comparable to the control foam. At an index of 105 (XXXHI), airflow, elongation and Japanese wet sets and HACS are improved over the control (XXX) and 50% dry compression sets are slightly elevated.

This test, also known as the ball rebound test, is very useful in evaluating the resilience of foams. The test consists of dropping a steel ball onto a foam specimen and noting the height of rebound. The apparatus, as shown in Figure 14-9, consists... 

Figure 11.3 Cover page of US Patent 3,431,323, with plots of apparent glass point and ball rebound with respect to % C2 side chain (parts a and b) and tensile strength with respect to % C2 side chain at 75 °C (part c) and 100 °C (part d). The % C2 side chain is equivalent to the 1-butene content in the hydrogenated polybutadiene block.

Two visco-elastic foam samples were selected for this investigation and were designated as VE foam 1 and 2. VE foam 1 is a toluene diisocyanate (TDI) based and VE foam 2 is a methylene diphenyl diisocyanate (MDI) based viscoelastic foam. Some basic material characterizations were run to characterize these two foams such as density, air flow, compression set (90%) according to the ASTM 395 B standard, resiUency (ball rebound), and resiliency (BASF recovery). 

---