Plasticized systems

Plastisols are often mixed and then stored rather than processed immediately (Fig. 5). It is of great importance in this case for the plasticizer to show htde or no paste thickening action at the storage temperature, and clearly it is not advisable to use a plasticizer of too great an activity, since grain sweUing, leading to plastisol viscosity increase, can occur at low temperatures for some active plasticizer systems. 

These pigments are recommended for most plastic systems because of their excellent stabiUty to chemicals, bleeding, and light. They are widely used in vinyls, polyethylene, polypropylene, and ceUulosic plastics. The Colourindex classes are Hsted as PR 123, 149, 179, and 190. 

The ability of some plastic systems to do this may be useful in schemes for handling the radiation output of nuclear devices, including the radiation from the fusion power machines under development. Obviously the application is not for shielding, which the heavy metals do much better, but rather for an energy level reduction system that would convert the high energy radiation to forms which would be more useful in power distribution. 

In the reinforced RIM (RRIM) process a dry reinforcement preform is placed in a closed mold. Next a reactive plastic system is mixed under high pressure in a specially designed mixing head. Upon mixing, the reacting liquid flows at low pressure through a runner system to fill the mold cavity, impregnating the reinforcement in the process. Once the mold cavity is filled, the plastic quickly completes its reaction. The complete cycle time required to produce a molded thick product can be as little as one minute. 

At the high polymer concentration used in plasticized systems the viscosity of amorphous polymer is given by the modified Rouse theory at low molecular weight, M - 2Mr [from equation (47)] and by the modified Doi-Edwards equation at high molecular weight. In the first case... 

Biggs (Ref. 21) discusses responses of simple dynamic systems in great detail, including the important intermediate case of elastic, perfectly-plastic systems. He also presents dimensionless response curves for various levels of elastic-plastic response, and for several different regular pulse shapes. 

Figure 16. P -I Diagram for Blast Loaded Rigid-Plastic System.

In many cases pigment-plasticizer pastes are also used for coloring PVC. Because of the mixing or embrittlement gap in the PVC-plasticizer system, which ranges from 5 to 18% for dioctyl phthalate for example, such pastes have little or no suitability for unplasticized PVC compounds. In this concentration range, which is specific for each plasticizer, no plasticizing effect is achieved, on the contrary the additive causes embrittlement of the PVC. 

Splay is a common term for surface imperfections that occur on injection-molded parts. Like the term gels for films, splay can occur from several root causes. Many of the root causes originate from the plasticating system and are related to moisture in... 

Gel polymer lithium-ion batteries replace the conventional liquid electrolytes with an advanced polymer electrolyte membrane. These cells can be packed in lightweight plastic packages as they do not have any free electrolytes and they can be fabricated in any desired shape and size. They are now increasingly becoming an alternative to liquid-electrolyte lithium-ion batteries, and several battery manufacturers. such as Sanyo. Sony, and Panasonic have started commercial production.Song et al. have recently reviewed the present state of gel-type polymer electrolyte technology for lithium-ion batteries. They focused on four plasticized systems, which have received particular attention from a practical viewpoint, i.e.. poly(ethylene oxide) (PEO). poly (acrylonitrile) (PAN). ° poly (methyl methacrylate) (PMMA). - and poly(vinylidene fluoride) (PVdF) based electrolytes. ... 

If one may consider the environment of a system as a stmcturally plastic system, the system and its environment must then be located in the intricate history of their stnictural transformations, where each one selects the trajectory of the other one. 

In the plastisol propellant process, it is essential that the resin particles not solvate too rapidly at processing temperature since a rapid increase in viscosity of the propellant mix interferes with the mixing and casting operation. There must be adequate pot life of the mixed propellant. The resin-plasticizer system itself is the dominating influence on pot life, and for this reason certain combinations cannot be used in the plastisol process. 

In addition to the effects on physical properties, an effect on ballistic properties may also be observed. If the polymer does not fill the entire space not occupied by the solids, when ignited the flame front may proceed by connected voids to yield an uncontrolled combustion condition. A porous condition can have an effect on the sensitivity to detonation as discussed in Chapter 10. The attractive forces between polymer and solids are probably the major contributing factor that causes differences in physical properties of propellant and causes one polymeric or polymer-plus-plasticizer system to be preferred over another. 

When plasticized polymers are in contact with the mother polymers, plasticizers are likely to migrate to mother polymers and the extent of their migration depends on a number of factors such as polymer-plasticizer system, polarity of polymer and plasticizer, crosslink density of polymer, molecular weight of plasticizer etc. 

Ree,T., Eyring,H. Theory of non-newtonian flow. I. Solid plastic system. J. Appl. Phys. 26,793-800(1955). 

Internally plasticized systems consisting of simple random copolymers, designed for use in flexible plastic articles, generally have an unsatisfactorily narrow use temperature range, since they soften more sharply than analogous externally plasticized systems or polyblends (mixtures of two or more polymers). 

Flory-Huggins /u. The Flory-Huggins n value measures the interaction between polymer and solvent (plasticizer). It derives from the so-called lattice theory, which represents a statistical approach to the behavior of polymer molecules in solution (10, 14, 75, 16, 22). The n value may be experimentally determined for any polvmer-plasticizer system (where the plasticizer can dissolve the polymer) by osmotic pressure measurements according to the relation ... 

This approach is very useful for polymer-plasticizer systems, and especially for cases where polymeric plasticizers, which evidently cannot be treated as volatile liquids, are being considered. 

Viscosity Measurements. Although in typical polymer-plasticizer systems, the polymer is the major component, it is possible to use the viscosity of dilute polymer solutions as a measure of the solvent power of the liquid for the polymer. Thus, liquids with high solvent power for the polymer cause a stretching out of the chain molecules, whereas a liquid of poor solvent power causes the chains to coil up. This is because, in the liquid with poor solvent power, the segments of the polymer chain (the monomer units) prefer to stay close to each other, while in a good solvent, interaction between polymer segments and solvent molecules is preferred. 

Where w again represents weight fraction M is molecular weight and subscripts 1 and 2 refer to polymer and plasticizer, respectively. We use the notation, cp here to indicate that the constant may vary from one plasticizer to another. Figure 1 shows a plot of Tg vs. 1/ Mn for several polystyrene-plasticizer systems. If Mi is very much larger than M2, Equation 7 becomes... 

Plasticized Polymers. As mentioned above the glass transition temperature Tg is lowered by adding certain organic liquids, the so called plasticizers. The illustration of polymers above T0 by means of a model remains valid also for plasticized systems. The configuration that is built up at the transition from the melt to the glass, in this case, remains below the glass temperature, too. Thus, we have an extended structure containing holes. ... 

The behavior of plasticizers in a polymer has already been examined by Wiirstlin (16) with dielectric measurements. However, this method is not sensitive enough to detect the plasticizer behavior in the system at small plasticizer concentrations. Luther and Weisel (12) have also pointed out this fact as a result of their DC measurements of PVC-plasticizer systems. The following measurements deal with the behavior of plasticizers in polystyrene. 

We shall conclude with some remarks on the structure of glassy polymers. If one frequently speaks of glass structures, this does not mean that there exists one definite glass structure similar to a crystal. In a macromolecular solid-e.g., the polystyrene-plasticizer system, entirely different glasses are obtainable, the macroscopic composition of which is always the same (8). In Figure 10 the full... 

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