What is solvent induced crystallization?
Solvent-induced crystallization can occur during the transport process in PET at low temperature. The important effect of changing the surrounding medium to solvent molecules is to reduce the glass transition temperature. This phenomenon is called “plasticization”.
What is induced crystallization?
Strain crystallization occurs when the chains of molecules in a material become ordered during deformation activities in some polymers and elastomers. In order to induce strain crystallization, the polymer or elastomer is stretched while its temperature is kept above its glass transition temperature.
What is stress induced crystallization?
This stress induced crystallization (change of atomic structure) is the first dominant mechanism of plastic deformation of the amorphous material. During the stress induced crystallization process, the flow stress stays at a constant level.
What is solvent diffusion?
Solvent diffusion is a prerequisite for the crystallization process. It is needed to plasticize the amorphous polymer in order for the macromolecular chains to be able to rearrange.
Why does crystallinity improve the strength of a polymer?
Crystallinity: The crystallinity of the polymer increases strength, because in the crystalline phase, the intermolecular bonding is more significant. Hence, the polymer deformation can result in the higher strength leading to oriented chains.
Are rubbers crystalline?
An amorphous solid is a solid that lacks an ordered internal structure. Examples of amorphous solids include glass, rubber, and plastics. The physical properties of amorphous solids differ from those of crystalline solids.
How does solvent affect diffusion?
Solvent density: As the density of a solvent increases, the rate of diffusion decreases. The molecules slow down because they have a more difficult time getting through the denser medium. If the medium is less dense, diffusion increases.
When a solution is separated from the pure solvent by a semipermeable membrane?
When a solution is separated from the pure solvent by a semipermeable membrane, the solvent molecules pass through it from pure solvent side to the solution side.
How does crystallinity affect modulus?
Crystallinity increases as a result of chain scission, so the Young’s modulus and strength may be expected to increase during degradation. This effect is offset by the fact that as crystallinity increases, molecular weight reduces, which in turn reduces the values of Young’s modulus and strength.
What happens when crystallinity increases?
Crystallinity defines the degree of long-range order in a material, and strongly affects its properties. The more crystalline a polymer, the more regularly aligned its chains. Increasing the degree of crystallinity increases hardness and density.
Is quartz crystalline or amorphous?
Quartz is a very hard crystalline substance, which is composed of one mole of Silicon and two moles of oxygen, which is Silicon dioxide or ….
| AMORPHOUS | CRYSTALLINE |
|---|---|
| Have an irregular arrangement of atoms in the solid. | Have regular arrangement of atoms in the crystal. |
Is glass amorphous or crystalline?
Glass is an amorphous solid. Although the atomic-scale structure of glass shares characteristics of the structure of a supercooled liquid, glass exhibits all the mechanical properties of a solid.