Polymer, ageing

With the inception of smart materials and stmctures, the world is on the brink of a new material age. Within this century the polymer age and the composite age have been experienced. These have now been foUowed by the smart material age. The implementation of smart materials into smart stmctures describes the smart material age more accurately. 

Fig. 7. Voigt model analysis of (a) lateral contact stiffness and (b) the response time, t, for a silicon nitride tip vs. poly(vinylethylene) as a function of frequency and polymer aging times. Reprinted with permission from ref [71].

The hydrolysis of Pu+lt can result in the formation of polymers which are rather intractable to reversal to simpler species. Generally such polymerization requires [Pu] > 10-8 M but, due to the irreversibility, dilution of more concentrated hydrolysis solutions below this value would not destroy the polymers. The rate of polymerization has been found to be third order in Pu concentrations and has a value of 5.4 X 10-5 moles/hr at 50°C and [Pu+I ]T t 0.006 M, [HNO3] s o.25 M (13). Soon after formation, such polymers can be decomposed readily to simple species in solution by acidification or by oxidation to Pu(Vl). However, as the polymers age, the decomposition process requires increasingly rigorous treatment. The rate of such irreversible aging varies with temperature, Pu(IV) concentration, the nature of... 

Polylactides, 18 Poly lactones, 18, 43 Poly(L-lactic acid) (PLLA), 22, 41, 42 preparation of, 99-100 Polymer age, 1 Polymer architecture, 6-9 Polymer chains, nonmesogenic units in, 52 Polymer Chemistry (Stevens), 5 Polymeric chiral catalysts, 473-474 Polymeric materials, history of, 1-2 Polymeric MDI (PMDI), 201, 210, 238 Polymerizations. See also Copolymerization Depolymerization Polyesterification Polymers Prepolymerization Repolymerization Ring-opening polymerization Solid-state polymerization Solution polymerization Solvent-free polymerization Step-grown polymerization processes Vapor-phase deposition polymerization acid chloride, 155-157 ADMET, 4, 10, 431-461 anionic, 149, 174, 177-178 batch, 167 bulk, 166, 331 chain-growth, 4 continuous, 167, 548 coupling, 467 Friedel-Crafts, 332-334 Hoechst, 548 hydrolytic, 150-153 influence of water content on, 151-152, 154... 

Materials and their development are fundamental to society. Major historical periods of society are ascribed to materials (e.g.. Stone Age, Bronze Age, Iron Age, Steel Age, Polymer Age, Silicon Age, and SUica Age). However, scientists will open the next societal frontiers not by understanding a particular material, but by optimizing the relative contributions afforded by a combination of different materials. 

The fundamental bilayer characteristics (two-dimensional ordering, phase transition, and phase separation, etc.,) are mostly maintained in the immobilized films with and without polymers. Aging or thermal treatment on the as-cast films improve the film properties because... 

Polymers, 20 389-412. See also Ethylene-propylene polymers Filled polymers Higher olefin polymers Polymerization Polysaccharides Shape-memory polymers (SMPs) SiC>2 polymer Special polymers Sulfur-containing polymers Thermosetting reactive polymers Water-soluble polymers aging of, 20 167... 

At the end of 1950, America had really arrived at the Polymer Age and progress has continued, as will be seen in the talks that will be given later in this Symposium. 

Polymers Aging Oxidation Cracking (Dil/Con) (Dil/Con) Hydrocarbons Hydrocarbons... 

Since most chemists, biochemists, and chemical engineers are now involved in some phase of polymer science or technology, some have called this the polymer age. Actually, we have always lived in a polymer age. The ancient Greeks classified all matter as animal, vegetable, and mineral. Minerals were emphasized by the alchemists, but medieval artisans emphasized animal and vegetable matter. All are largely polymeric and are important to life as we know it. 

Over 100 billion pounds (50 million tons) of synthetic polymers is produced annually in the United States (Tables 1.5 through 1.8), and the growth of the industry is continuing at a fast rate. There is every reason to believe that this polymer age will continue as long as petroleum and other feedstocks are available and as long as consumers continue to enjoy the comfort, protection, and health benefits provided by elastomers, fibers, plastics, adhesives, and coatings. The 100 billion pounds of synthetic polymers consumed each year in the United States translates to over 300 pounds for every man, woman, and child in the United States. This does not include paper and wood-related products, natural polymers such as cotton and wool, or inorganic polymers (Table 1.8). 

Amino-1,2,4-dithiazole-5-thione may be used for corrosion inhibition of Cu-)-Zn powder mixture <86Mi 413-03) or for inhibition of polymer ageing <85URPl 142485) A-alkoxy derivatives inhibit corrosion of iron <91URP1650683,82MI413-06,82MI413-07). 1,2,4-Dithiazolidines (247 = H,... 

Polymer immobilization. Mo-peroxide, 427 Polymerization agents, 621, 622 peroxide value, 661, 662 peroxycarboxyUc acids, 698 radical polymerization, 697, 707 styrene, 697, 720 sulfonyl peroxides, 1005 thermochemistry, 155 Polymers aging, 685 autoxidation, 623 hydroperoxide determination, 685 Poly(methacrylonitrile peroxide)... 

This is made particularly difficult in the case of water-soluble polymers for reasons of their chemical nature. The phenomenon of polymer aging should also be mentioned in this connection (see Sect. 6.3.2). 

A Basic Kinetic Model to Begin the Study of Polymer Aging... 

Using TPM as described in Section 10.2 on swollen polymers can give access to the mesh size distribution (MSD) in the swollen state. The ability of the polymer to swell is connected to the reticulation level, which in turn can vary greatly during polymer aging. 

J. Verdu, X. Colin, B. Fayolle, and L. Audouin, Methodology of lifetime prediction in polymer aging. J. Testing Eval., 35(3), 289-296 (2007). 

We now well appreciate, of course, that polymers are virtually everywhere. Some of them occur naturally, and we continue to better understand their compositions, structures, and properties. Many of these materials have been used since the dawn of human existence, for food, obviously. Cellulose alone has been essential for clothing, fire, shelter, tools, weapons, writing, and art. Leather is probably the result of the first synthetic polymer reaction, essentially the crosslinking of protein (elastin). How we progressed over time to the Polymer Age is a fascinating series of stories, some of which are well worth recounting here. 

Polymer Age, 46 Polymer blends, 71, 98 Polymer Chemistry Innovations, Inc., 189 Polymer cycle, 178-179, 179 Polymer science future of, 203-219 history of, 45-79 relationships of, xxiv... 

We have been living in the Polymer Age for quite some time. My fervent belief, shared by my many colleagues, is that we must increase everyone s awareness of these essential materials, not just that of the chemists and engineers who will be working with them professionally. I hope this book will facilitate that educational process in some small way. 

All polymers age in the same way, their relaxation times increasing proportionally to the ageing time. Proposition 6 is illustrated by Fig. 13.51. 

Special attention Nikolai M. Emanuel paid to the problem of chemical physics of polymer ageing and stabilization. Results obtained at that time were summarized in monograph by N.M. Emanuel and A.L. Buchachenko [1]. 

N.M. Emanuel, A.L. Buchachenko, Chemical physics of polymers ageing and stabilization, Moscow Nauka (1982) (in Russian). 

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