Glass plasticizers effect

Physical and ionic adsorption may be either monolayer or multilayer (12). Capillary stmctures in which the diameters of the capillaries are small, ie, one to two molecular diameters, exhibit a marked hysteresis effect on desorption. Sorbed surfactant solutes do not necessarily cover ah. of a sohd iaterface and their presence does not preclude adsorption of solvent molecules. The strength of surfactant sorption generally foUows the order cationic > anionic > nonionic. Surfaces to which this rule apphes include metals, glass, plastics, textiles (13), paper, and many minerals. The pH is an important modifying factor in the adsorption of all ionic surfactants but especially for amphoteric surfactants which are least soluble at their isoelectric point. The speed and degree of adsorption are increased by the presence of dissolved inorganic salts in surfactant solutions (14). 

Aluminum Foil. Studies of various foods wrapped in aluminum foil show that food products to which aluminum offers only fair resistance cause little or no corrosion when the foil is in contact with a nonmetallic object (glass, plastic, ceramic, etc.) The reactions, when found, are essentially chemical, and the effect on the foil is insignificant. However, when the same foods are wrapped or covered with foil that is in contact with another metallic object (steel, tinplate, silver, etc.), an electrochemical or galvanic reaction occurs with aluminum acting as the sacrificial anode. In such cases, there is pitting corrosion of the foil, and the severity of the attack depends primarily on the food composition and the exposure time and temperature. Results obtained with various foods cov-... 

The increase in the length of the side chain results normally in an internal plasticization effect caused by a lower polarity of the main chain and an increase in the configurational entropy. Both effects result in a lower activation energy of segmental motion and consequently a lower glass transition temperature. The modification of PPO with myristoyl chloride offers the best example. No side chain crystallization was detected by DSC for these polymers. 

The so called plasticization effect, i.e., the depression of the glass transition temperature is also an important feature the sorbed gas acts as a kind of lubricant , making it easier for chain molecules to slip over one another, and thus causing polymer softening. 

The model of Condo permits the determination of the limiting pressure at which the glass state exists, on the basis of a reduced number of parameters (only the glass transition temperature of the pure polymer is needed to calibrate the energy parameter) for this reason, it seems particularly useful for the prediction of the plasticizing effects. 

The data in Fig. 13 show that the glass transition temperatures of all materials is reduced by the absorption of water. This seems to be due to the plasticizing effect of the water on the binder. There is a marked difference between the elastic states of the dressed and undressed foams, the latter becoming much more plastic after immersion in water. Increased plasticity is due to the loss of adhesion between the binder and the filler, indicating that water absorption by syntactic foams is multistaged. 

Guo and coworkers (29) examined the chemical stability of lyophilized quinapril HC1 as a function of initial solution pH. Lyophilization of different quinapril solutions produces mixtures of amorphous quinapril and its neutralized form, with glass transition values between the Tg values of quinapril and neutralized quinapril. As the fraction of quinapril increases the rate of chemical degradation increases relative to that of quinapril HC1 alone. This is most likely caused by the plasticizing effects of neutralized quinapril. 

For miscible blend phases, these parameters need to be described as a function of the blend composition. In a first approach to describe the behavior of the present PPE/PS and SAN/PMMA phases, these phases will be regarded as ideal, homogeneously mixed blends. It appears reasonable to assume that the heat capacity, the molar mass of the repeat unit, as well as the weight content of carbon dioxide scale linearly with the weight content of the respective blend phase. Moreover, a constant value of the lattice coordination number for PPE/PS and for SAN/PMMA can be anticipated. Thus, the glass transition temperature of the gas-saturated PPE/SAN/SBM blend can be predicted as a function of the blend composition (Fig. 17). Obviously, both the compatibilization by SBM triblock terpolymers and the plasticizing effect of the absorbed carbon dioxide help to reduce the difference in glass transition temperature between PPE and SAN. 

Although sedative antihistamines do not potentiate the effect of alcohol, they should be avoided in excess quantity. Overdose of astemizole can be treated with gastric lavage and supportive measures.86 Coadministration of astemizole and ter-fenadine with antiarrhythmics, antipsychotics, cisapride, and diuretics should be avoided. Chlorpheniramine maleate has been found to be incompatible with phe-nobarbitone sodium, kanamycin sulfate, and calcium chloride. Cyclizines have been used alone or with opioids in tablets or in injectable form for euphoric effects. Cyproheptadine has shown dependence in long-term use. Diphenhydramine is reported to be incompatible with amphotericin, cephalothin sodium, and hydrocortisone sodium succinate. Diphenhydramine and pheniramine maleate are sometimes used as drugs of abuse. Studies have shown that promethazine is adsorbed onto glass, plastic containers, and infusion systems.87... 

A reduced treatment of the plasticizer effect starts with the equation developed by Bueche (1962), who gave the following equation for the glass transition temperature of a plasticized polymer... 

Doping a neat glass forming system with smaller molecules leads to a reduction of the glass transition temperature Tg.176 In polymer research, this behavior is well known as polymer/plasticizer effect. However, it applies to any mixture provided that the Tg value of the additive is significantly lower than that of the main component. 

The plastic deformation exhibited by nonductile crystalline ceramics is not significant enough for deformation processes to be of much use in the fabrication of bulk articles. Noncrystalline materials (e.g. glasses) deform by the same mechanism as liquids, viscous flow. However, in a glass the effect is only pronounced at temperamres elevated enough to decrease the viscosity. 

Figure 7.2. Glass transition of amorphous monosaccharides and some food materials as a function of water activity (Reproduced with permission from Roos and Karel, 199 Id, Plasticizing effect of water on thermal behavior and crystallization of amorphous food models, J. Food Sci. 56, pp. 38-43, Institute of Food Technologists.)...

Figure 10 Effect of phototherapy (blue) light, Intralipid tat emulsion, and storage container composition on the vitamin A levels in admixtures, (o) Glass, Intralipid (x) plastic. Intralipid ( ) glass. Intralipid+light (+) plastic. Intralipid+light (A) glass ( ) plastic (A) glass+light ( ) plastic+light. Source From Ref. 92.

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