Solvent-induced stress

Additives that eliminate internal strains, such as lubricants, plasticizers, etc., or that may affect the crystallization of crystalline polymers, such as finely powdered fillers or miscible elastomers (PIB in PE), will overcome solvent-induced stress corrosion. 

Table 2. Solvent-Induced Stress Crazing of Polyimide 4 Crosslinked by Crosslinker 1,2, and 3 at 300 °C...

This form is useful in the study of forces applied to solutes or to groups in proteins in aqueous solutions. The first term is referred to as the direct force and the second term as the solvent-induced forces. (Note that the gradient operates only on U R, R ), as we have stressed by the square brackets.)... 

If a solute A approaches a water molecule w in the gaseous phase, it has the same probability of attaching to any region on the surface of w. (This is not precisely the case for real molecules. However, we make this assumption to stress the new effect of the solvent-induced interaction in producing the orientational preference discussed below.)... 

Solvent-induced or detergent-induced failure frequently occurs without applied stress, as a result of residual stresses from the initial molding process. Thus, it is possible to clean one acrylic piece with alcohol and experience no problem, while a second piece may craze or disintegrate due to residual stress at a corner. The liquid need not attack the bulk of the polymer, it only acts on the strained region at the tip of a crack. 

Commercial uses of chlorinated solvents cause serious stresses on the stability of the solvent. These stresses include heat, hydrolysis (reaction with water), metal contact, and air induced oxidation. The addition of selected organic inhibitors (stabilizers) to the solvent helps ensure solvent stability in the most stressful applications. The organic inhibitors used in proprietary chlorinated solvents include antioxidants, acid acceptors, and metal stabilizers. The unsaturated solvents like trichloroethylene and perch loroethylene require amine or phenolic-type antioxidants to minimize the potential oxidative degradation. Acid acceptors are low... 

The first one is based on the deposition of conposite films made of powder particles dispersed in a sol-gel matrix. Upon solvent evaporation and subsequent film firing, the sol-gel matrix acts to bind the powder phase, while the latter acts to decrease the sol-gel matrix stiffness, in order to relax capillary and thermally induced stresses. This method was adapted to pneumatic AASG deposition of thick films, followed by heat-treatment in the range 300—450°C, for electrical insulation on steel substrates (Olding, 2001), or wear protection on metallic alloys (Wilson, 2001). 

Diffusion of solvent in the polymeric material may induce swelling causing changes in its internal structure if there are heterogeneities which induce stresses between more or less swollen areas. These areas may be amorphous (relatively accessible) or crystalline (relatively inaccessible). This swelling can also occitr when the kinetics of diffusion of the solvent create concentration gradients. 

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