Technological rigidity

Tests of the relationship between novelty and technological rigidity provided especially interesting results. The most novel... 

Today s plants are, however, not as technologically rigid as they may seem. Customers ask for tailor-made products, often in small quantities, and delivered as soon as possible. This increases the need for flexibility in plants and processes. Added-on safety usually decreases flexibility because it involves additional safety artifacts such as neutralizing baths, shut-off valves, and bypass piping, whereas inherently safer technologies can increase flexibility because the processes used are often simpler and in any event do not require added-on technology that constrain future modifications. 

All these technologies rigidly obey Newton s laws and the laws of thermodynamics. Students who learned cookbook techniques for solving problems in 1954 were not well prepared for the technologies that appeared during the next 10 years, but those who learned the basic, ideas and how to apply them could adapt to any one of them. There is little reason to believe that the pace of technological change will be slower in the future. If we... 

The most innovative photohalogenation technology developed in the latter twentieth century is that for purposes of photochlorination of poly(vinyl chloride) (PVC). More highly chlorinated products of improved thermal stabiUty, fire resistance, and rigidity are obtained. In production, the stepwise chlorination may be effected in Hquid chlorine which serves both as solvent for the polymer and reagent (46). A soHd-state process has also been devised in which a bed of microparticulate PVC is fluidized with CI2 gas and simultaneously irradiated (47). In both cases the reaction proceeds, counterintuitively, to introduce Cl exclusively at unchlorinated carbon atoms on the polymer backbone. 

While these different pohcies vaiy broadly in form, their objective is essentially the same to substitute flexible economic-incentive systems for the current rigid, technology-based regulations that specify exactly how companies must comply. These market mechanisms have made regiilating easier for EPA and less burdensome and costly for industiy. 

The bulk properties of a polymer ean often be altered considerably by the incorporation of additives. Probably the most well-known examples of this occur in rubber technology where variations in the choice of additives can produce such widely differing products as tyres, battery boxes, latex foam upholstery, elastic bands and erasers. It is also possible to achieve variations as extensive as this amongst plastics materials, in particular with PVC from which rigid rainwater piping, baby pants, conveyor belting, footballs and domestic insulating flex may all be prepared. 

Sandwich panels of rigid polyurethane - HCFC- 141b, HCFC-22, blends of HCFC-22 and -141b, pentane, and HFC-134a are now used as alternatives to CFCs in this application. In the long term, HFCs and carbon dioxide/water will be the replacement technologies. 

Rigid polyurethane pipe construction - CFCs in this application are being replaced by carbon dioxide/water, HCFC-22, blends of HCFC-22 and -142b, HCFC-141b, and pentanes. Long-term alternatives will include HFCs and carbon dioxide/water. For district central heating pipes, pentane and carbon dioxide/water are the preferred technologies. 

Hence, the main aim of the technological process in obtaining fibres from flexible-chain polymers is to extend flexible-chain molecules and to fix their oriented state by subsequent crystallization. The filaments obtained by this method exhibit a fibrillar structure and high tenacity, because the structure of the filament is similar to that of fibres prepared from rigid-chain polymers (for a detailed thermodynamic treatment of orientation processes in polymer solutions and the thermokinetic analysis of jet-fibre transition in longitudinal solution flow see monograph3. ... 

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