Rebounding

Rebound flexible foam Rebound hardness test Receptor... 

Recovery, Rebound, or Nerve. Uncured latex stock tends to recover its previous shape after being roUed or extmded during processing. 

North American HF production capacity has declined since the early 1980s and several smaller producers, such as Harshaw and Essex, have closed plants. Production is expected to continue to decline in the short term because of chlorofluorocarbon (CPC) cutbacks, but is expected to rebound later in the 1990s as replacement hydrochlorofluorocarbons are introduced to the marketplace. 

Many types of hardness tests have been devised. The most common in use are the static indentation tests, eg, Brinell, Rockwell, and Vickers. Dynamic hardness tests involve the elastic response or rebound of a dropped indenter, eg, Scleroscope (Table 1). The approximate relationships among the various hardness tests are given in Table 2. 

Mohs hardness values may vary Shore hardness number is derived from rebound height of standard steel ball when dropped on material from standard height. 

The coefficient of restitution is defined as the ratio of the vertical components of the impact and rebound velocities resulting when a bad is dropped or thrown onto a playing surface. The velocities or related rebound heights may be measured photographically. Criteria such as bad inflation pressure, air temperature, and other detads must be specified. 

Small tire chips have also been utilized as a soil amendment to improve athletic playing fields (see Recreational surfaces). A patented process marketed under the trade name Rebound (fai Tire) combines cmmb mbber from scrap tires with composted organic material to reduce soil compaction, resulting in better athletic playing surfaces (52). Installations have been made in Florida, California, Colorado, Hawaii, Maryland, Michigan, Missouri, Nevada, Virginia, and Wisconsin. 

The property of polybutadiene of most interest to the mbber compounder is excellent abrasion resistance coupled with excellent resilience. The polymer has very high rebound and low heat generation. With a few exceptions, such as the core of soHd golf balls, the polymer is blended with other polymers to take advantage of its excellent abrasion and rebound. Uses in North America are as follows tires, 500,000 t (74%) plastic modification,... 

Filler loading Volume, parts Mooney viscosity Optimum cure (at 141°C), min Modulus (at 300%), MPa Tensde strength, MPa Elongation, % Hardness, Shore A NBS abrasion (ASTMD1630) Rebound, %... 

When clonidine is withdrawn abmpdy, patients may experience a rebound hypertensive phenomenon, whereia blood pressure rises rapidly to a level higher than the predmg level. These patients may experience symptoms of headache, tachycardia, agitation, and nervousness. If rebound hypertension occurs, resumption of clonidine therapy or adrninistration of phentolamine reduces the blood pressure. For clonidine withdrawal, the dose should be reduced gradually over a two-week period. The principal side effects are sedation, dry mouth, drowsiaess, di22iQess, and fatigue. 

The forecasts made in 1985 (77) of 8—8.5% worldwide aimual growth have not materialized. The 2 x lOg + /yr engineering plastic production reported for 1985—1986 has remained fairly constant. Whereas some resins such as PET, nylon-6, and nylon-6,6 have continued to experience growth, other resins such as poly(phenylene oxide) have experienced downturns. This is due to successhil inroads from traditional materials (wood, glass, ceramics, and metals) which are experiencing a rebound in appHcations driven by new technology and antiplastics environmental concerns. Also, recycling is likely to impact production of all plastics. 

D. Critical hmit of granule size cm in energy required for rebound ... 

Rotor Impactors The rotor of these machines is a cylinder to which is affixed a tough steel bar. Breakage can occur against this bar or on rebound from the walls of the device. Free impact breaking is the principle of the rotor breaker, and it does not rely on pinch crushing or attrition grinding between rotor hammers and breaker plates. 

FIG. 20-68 Mechanisms of granule coalescence for low- and high-deformability systems. Rebound occurs for average granule sizes greater than the critical granule size D. K = deformability. 

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