Table of Contents
- 1 Why do we take average molecular weight of polymers?
- 2 Why plastics have high molecular weights?
- 3 What is average molecular weight of polymer?
- 4 What is the average weight and molecular mass of polymers?
- 5 How do you find the average molecular weight of a polymer?
- 6 What are some properties that depend on the average molecular weight?
- 7 What is the MW of a polymer?
Why do we take average molecular weight of polymers?
When studying a polymer, the most relevant average depends on the property being investigated: for example, some properties may be more affected by molecules with high molecular weight than those with low molecular weight, so the weight average is chosen since it highlights the presence of molecules with high molecular …
Why plastics have high molecular weights?
Because of the structure of the molecules, polymeric materials have different properties compared to other materials, like metals. Specifically, the relatively high molecular weight and long polymer chain length result in entanglement, and the lack of covalent intermolecular bonds facilitates polymer chain mobility.
What is the significance of average molecular weight?
The average molecular weight is distribution of values of weights of the polymer and is a useful statistical method to characterize polymers. For example, polymers molecular weight is not one molecular weight or size but a distribution of weights.
What is average molecular weight of polymer?
Most of the practically useful polymers have a DP between 200 to 2000, corresponding to a molecular weight range from 20,000 to 200,000.
What is the average weight and molecular mass of polymers?
The distribution of molecular weights in a polymer sample is often described by the ratio of the weight average molecular weight to the number average molecular weight. In this case the ratio is 531,600/500,000 = 1.063….
| Number of Molecules | Mass of each Molecule |
|---|---|
| 20 | 500,000 |
| 13 | 450,000 |
| 10 | 400,000 |
| 8 | 350,000 |
Why does the polymer have average molecular weight rather than single absolute molecular weight?
The MW is determined by summing the mass of all of the individual atoms in a molecule. The molecular weight of a polymer is expressed as an average, rather than an absolute figure, because polymer samples contain a mixture of chains of atoms of differing lengths.
How do you find the average molecular weight of a polymer?
The number average molecular weight Mn is calculated as. Mn = ∑ iNiMi ∑ iNi. where Mi is the molecular weight of a chain, Ni is the number of chains of that molecular weight, and i is the number of polymer molecules [24]. View chapter Purchase book. Read full chapter.
What are some properties that depend on the average molecular weight?
A classic example of property that depends on weight average molecular weight is light scattering. where Mi is the molecular weight of a chain, Ni is the number of chains of that molecular weight, and i is the number of polymer molecules [25].
What is the molecular weight of polyester resin?
The general-purpose unsaturated polyester (UP) resin is a linear polymer with the number average molecular weights in the range of 1200–3000 g/mol. Depending on the chemical composition and molecular weight, they can be viscous liquids or solids.
What is the MW of a polymer?
Weight average molecular weight (M w) measuring system includes the mass of individual chains, which contributes to the overall molecular weight of the polymer. It is based on the fact that bigger molecules contain more mass than smaller molecules.