Ring-Hip

With a batch process, such as hot isostatic compaction (HIP), heat exchange as used in a continuous reactor is not possible, and it is common practice to provide a furnace within the pressure vessel which is thermally insulated to ensure that the temperature of the vessel does not rise above 300°C. Most HIP operations involve gas pressures in the range 70—200 MPa (10—29,000 psi) and temperatures of 1250—2000°C, occasionally 2250°C (74). The pressure vessel may have a bore diameter from 27 to 1524 mm (75) and is nearly always provided with threaded closures sealed with O-rings made of elastomer provided the temperature is low enough. 

X-ray photograph of a hip joint, a rectangular piece of foam ceramics, a round glass reinforced with titanium fibers and a ring made of metal and ceramics (picture by J Bormans). 

Polymers derived from polystyrene but having alkyl or aryl groups substituted at the benzene ring were synthesized in an effort to improve some of polystyrene properties such as the impact resistance and obtain qualities similar to those achieved using copolymers with 1,3-butadiene (high impact polystyrene or HIPS). The polymers included In this class are poly(3-methylstyrene), poly(4-methylstyrene) CAS 24936-41-2, poly(4-phenylstyrene) CAS 25232-08-0 [115], as well as poly(2-vinylnaphthalene) CAS 28406-56-6. Some of the reports regarding thermal decomposition of these polymers are summarized in Table 6.2.10. 

Table 6.4 gives the output of Program 5 under certain conditions. We see that for a layer thickness z/ = 2.5 x 10" cm, Program 5 finds a value of Hip close to that obtained by other techniques [Table 6.4(a)]. Orthogonal collocation is used to simulate rotating ring disk electrodes and cyclic voltammetry for CE and EC mechanisms. Furthermore orthogonal collocation is used to characterize diffusion at microelectrodes and microelectrode arrays. ... 

Ring P.A. 1968. Complete replacement arthroplasty of the hip by the ring prosthesis. / Bone Joint Surg 50 720-731. 

Penman, H.G. and Ring, P.A. (1984) Osteosarcoma in association with total hip replacement. J. Bone Joint Surg. 66B, 632-634. 

The key is the ethane bridge between the aromatic rings, versus an oxygen atom in decabromodiphenyl ether (decaBDPE). The spatial arrangement of the rings does not allow easy bond formation of the type necessary to produce dioxin or furan structures. EBP is a direct replacement for decaBDPE in many applications such as HIPS for electrical and electronic (E E)... 

With a density of 1.04 to 1.06g.cm 3, PS sinks slowly in water. When heated in a flame, softens and burns readily with a sooty, yellow flame produces a lot of smell, smoke and soot. Burning droplets are also formed. Characteristic smell of styrene which is even more noticeable if the flame is extinguished. At temperatures above approximately 90° C (194° F), the material becomes rubbery and then gradually melts decomposes at approximately 320° C (608° F) to give a styrene-smell and a neutral condensate. Moldings are brittle and emit a ringing sound if dropped on a hard surface (so does TPX). Does not cut easily or cleanly with a knife. A common feature of all styrene plastics is their resistance to aqueous media such as salt solutions, acids of medium concentration and alkalis. Aliphatic hydrocarbons, for example, heptane and cyclohexane, readily attack PS and HIPS but... 

---