Amorphous catastrophic failure

Solubility and Solvent Resistance. The majority of polycarbonates are prepared in methylene chloride solution. Chloroform, i7j -l,2-dichloroethylene, yy -tetrachloroethane, and methylene chloride are the preferred solvents for polycarbonates. The polymer is soluble in chlorobenzene or o-dichlorobenzene when warm, but crystallization may occur at lower temperatures. Methylene chloride is most commonly used because of the high solubiUty of the polymer (350 g/L at 25°C), and because this solvent has low flammabiUty and toxicity. Nonhalogenated solvents include tetrahydrofuran, dioxane, pyridine, and cresols. Hydrocarbons (qv) and aUphatic alcohols, esters (see Esters, organic), or ketones (qv) do not dissolve polycarbonates. Acetone (qv) promotes rapid crystallization of the normally amorphous polymer, and causes catastrophic failure of stressed polycarbonate parts. 

Solubility and Solvent Resistance. The majority of polycarbonates are prepared in methylene chloride solution Chloroform, eir-1,2-dichlorocthylcnc, rym-tclrachlorocthanc. and methylene chloride arc the preferred solvents for polycarbonates. Flydrocarbons and aliphatic alcohols, esters, or ketones do not dissolve polycarbonates. Acetone promotes rapid crystallization of the normally amorphous polymer, and causes catastrophic failure of stressed polycarbonate parts. 

These ductile features of these glasses may be observed microscopically in Fig. 3.18a and b, respectively. However, the stress—strain curves of these Zr-based amorphous glasses did not display appreciable macroscopic plastic deformation prior to catastrophic fracture, rather they mainly deformed elastically, followed by catastrophic failure along their shear bands. Examination of the fracture regions... 

---