Rubbery solid

The solidity of gel electrolytes results from chain entanglements. At high temperatures they flow like liquids, but on cooling they show a small increase in the shear modulus at temperatures well above T. This is the liquid-to-rubber transition. The values of shear modulus and viscosity for rubbery solids are considerably lower than those for glass forming liquids at an equivalent structural relaxation time. The local or microscopic viscosity relaxation time of the rubbery material, which is reflected in the 7], obeys a VTF equation with a pre-exponential factor equivalent to that for small-molecule liquids. Above the liquid-to-rubber transition, the VTF equation is also obeyed but the pre-exponential term for viscosity is much larger than is typical for small-molecule liquids and is dependent on the polymer molecular weight. 

Some Outstanding Problems in the Mechanics of Rubbery Solids... 

We conclude that high internal stresses are generated by simple shear of a long incompressible rectangular rubber block, if the end surfaces are stress-free. These internal stresses are due to restraints at the bonded plates. One consequence is that a high hydrostatic tension may be set up in the interior of the sheared block. For example, at an imposed shear strain of 3, the negative pressure in the interior is predicted to be about three times the shear modulus p. This is sufficiently high to cause internal fracture in a soft rubbery solid [5]. 

Nevertheless, through scrupulous purification of the reaction components and rigorous control of the reaction conditions it is possible to isolate the polymer in a state of good purity, by the reaction of potassium pyrrolide with (NPC 2)x in tetrahydrofuran at room temperature (Equation l). Addition of water to the reaction mixture precipitates the polymer as a white rubbery solid which hardens on drying. A 3IP NMR spectrum of a typical reaction product is given in Figure 2. 

Bell, L.N., Bell, H.M., and Glass, T.E. 2002. Water mobility in glassy and rubbery solids as determined by oxygen-17 nuclear magnetic resonance Impact on chemical stability. Lebensm. 

Thioetherification of PECH is feasibly performed in DA-solvents as already described in the patent (20J. For example, the highest substitution was obtained by the reaction of P(ECH-EO)(1 1 copolymer of epichloro-hydrin and ethylene oxide) and equimolar thiophenoxide in HMPA at 100°C for 10 h as DS 83% for sodium and 93% for potassium salts. The DS in our nucleophilic substitution was estimated by the elemental analysis as well as the titration of liberated chloride ion with mercuric nitrate (21). In the latter method, reacted medium was pretreated with hydrogen peroxide when the reductive nucleophiles which can react with mercuric ion were used. As described before for PVC, thiolation was also achieved conveniently with iso-thiuronium salt followed by alkaline hydrolysis without the direct use of ill-smelling thiolate. The thiolated PECH obtained are rubbery solids, soluble in toluene, methylene chloride, ethyl methyl ketone and DMF and insoluble in water, acetone, dioxane and methanol. 

An amorphous material such a polystyrene does not solidify sharply. It goes from a viscous liquid to a rubbery solid, then to a leathery solid. Finally, it becomes a glassy solid. This last change is a sharper one and the temperature at which it occurs is called the glass transition temperature, Tg. Or upon heating a polymer, it is the temperature at which the polymer loses... 

In plastisol propellants, however, all polymerization reactions are complete before propellant manufacture begins. Solidification is accomplished through solvation (or solution) of the solid resin (or polymer) particles in the nonvolatile liquid, which has been selected to be a plasticizer for the resin. Solvation or curing is accomplished by heating to a temperature at which the resin particles dissolve rapidly (within a matter of a few minutes) in the plasticizer to form a gel which on returning to room temperature has the characteristics of a rubbery solid. 

Viton-A (copolymer of hexafluoropropylene and vinylidene fluoride) Rubbery solid used as a binder... 

He gave the project to an assistant, who tried all sorts of reaction conditions — to no avail. Then one weekend he left one of his experiments sitting in a flask and discovered on Monday morning that it had turned into a rubbery solid. Analysis showed that residual hydrochloric acid had reacted with the vinylacetylene to make a synthetic rubber. Neoprene... 

XTX-8003 (eXTrudable explosive). Los Alamos National Scientific Laboratory (LASL) designation for an extrudable expl contg PETN (80 wt% 69.9 vol %) coated with a low-temp vulcanizing silicone resin, Sylgard 182 (20 wt % 30.1 vol %) atomic compn Ci. 8<>H3.64N , 0103 3 jSi0.27 white putty curable to rubbery solid d, TMD 1.556g/cc, nominal 1.50-1.53g/cc mp 129-135°. XTX-8003 is used in special applications that require expls with small detonation failure diameters... 

Physical properties, which depend on molecular weight, the nature of the alkyl group, the nature of the initiator, stereospecificity, and crystallinity, range from viscous liquids, through sticky liquids and rubbery solids, to brittle solids. Polyetliers with long alkyl side chains are waxy, however, as the alkyl group in such cases dominates physical properties,... 

Aminoethylpolyurethane(AEPU). A white, rubbery solid contg ca 30.6% N was obtained by treating 1 g of polyurethane(dis solved in 25 ml of toluene) with 10 ml ethyleneimine and 0.1 mi benzyl chloride in a sealed tube at 100° for 43 hours. Material remaining in-sol in ° reac ion ynivt cuacViA/1... 

Most addition polymers are thermoplastics that is, they are hard at room temperature but soften and eventually melt as they are heated. At low temperatures there is very little motion of the molecules and the polymer is glasslike and brittle. As the temperature of the polymer is raised, it passes through its glass transition temperature (Tg). Above J , more motion of the chains is possible and the polymer is a rubbery solid. Eventually, the polymer passes through its crystalline melting point (Tm) and melts to form a viscous liquid. Many semicrystalline polymers are most useful at temperatures between Tg and Tm. Both Tg and Tm increase as the crystallinity of the polymer increases and as the strength of the intermolecular forces between the polymer chains increases. The total intermolecular force increases as the length of the polymer chains increases. 

II. Mollielasts (Elastomers) Soft and flexible rubbery solids T > Tg 0 Tow Polybutadiene... 

The highest sonic damping is obtained in transition zones. The glass transition can be used for this purpose if cross-linked polymers are applied, with a rubbery solid state until far above Tg. Very interesting work in this field was done by Sperling and his coworkers (1987,1988) who studied the damping behaviour of homopolymers, statistical copolymers and interpenetrating networks (IPNs) of polyacrylics, polyvinyls and polystyrenes. 

The product was a white rubbery solid which swelled strongly in methanol, gradually de-compd at ca 150° and melted when placed on a block at 300P. When 3 0 g of this product was perchlorated widi 70% perchloric acid in methanol, the AETDIP was obtained in a low yield(4.7 g instead of the calcd 7.0 g) but the perchlorate burned readily leaving only a small residue... 

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