What is glassy state in polymers?
Strictly, any amorphous polymer is glassy at temperatures below its Tg, but in practice a glassy polymer refers to those polymers which are in their glassy state at room temperature, thus to amorphous polymers with a glass transition temperature above room temperature, in contrast to rubbery polymers, which have a Tg …
What is a glassy state?
The first improved definition is: “Glass is a nonequilibrium, non-crystalline state of matter that appears solid on a short time scale but continuously relaxes towards the liquid state.” This is an intuitive description for the general public and young students.
What is glassy and solid crystalline?
To clarify, we use the terms “glass” or “glassy state” to refer to a non-crystalline state obtained specifically by supercooling a liquid and the term “amorphous” to discuss non-crystalline solids obtained by any other means4.
What are the differences between glassy and rubbery polymers?
Rubbery polymers generally have higher diffusion coefficients than glassy polymers. Diffusion selectivity advantage of glassy polymers is more modest than suggested. Rubbery polymers have modestly low dependence on diffusion selectivity. Glassy polymers dominate the upper bound due to higher solubility coefficients.
What is degree of polymerization in chemistry?
The degree of polymerization, or DP, is the number of monomeric units in a macromolecule or polymer or oligomer molecule. The degree of polymerization or chain length is then 1000 by the first (IUPAC) definition, but 500 by the second.
What is glass and glassy state?
THE GLASSY STATE. Glass is a state of matter. Glasses combine some properties of crystals and some of liquids but are distinctly different from both. Glasses have the mechanical rigidity of crystals, but the random disordered arrangement of molecules that characterizes liquids.
What are the properties of glass?
The main characteristics of glass are transparency, heat resistance, pressure and breakage resistance and chemical resistance. The surface of glass is affected if it is exposed for a long time to alkalis (and ammonia gases in damp air) in conjunction with high temperatures.
How is glass non crystalline?
Glass is an amorphous (noncrystalline) solid material, due to the short range order, i.e., there is no regularity in the arrangement of its molecular constituents.
What is the glass transition temperature?
Glass transition temperatures are very variable ranging from 140 °C to 370 °C according to the grades, curing process and the moisture content: For a defined grade, the glass transition temperature increases from 50 °C during post cure.
Is PVC a glassy polymer?
Polymer Properties In glassy polymers, D0 has been shown to decrease enormously (by up to ten orders of magnitude) with increasing permeant size expressed as van der Waals volume15 as shown in Figure 5 for poly(vinyl chloride) (PVC).
What is rubbery state?
The rubbery state lends softness and flexibility to a polymer. You may have experienced the glass transition of chewing gum. At body temperature the gum is soft and pliable, which is characteristic of an amorphous solid in the rubbery state.
What is xn in polymers?
The Degree of polymerization (DP or Xn) is defined as number of repeating monomer units in the polymers. The Degree of a polymerization is calculated by taking ratio of molecular weight of the polymer and molecular weight of the repeat unit.
https://www.youtube.com/watch?v=5lH_Xt2KUjA