What is weight-average degree of polymerization?

What is weight-average degree of polymerization?

The weight-average degree of polymerization is a weighted mean of the degrees of polymerization, weighted by the weight fractions (or the overall weight of the molecules) of the species. It is typically determined by measurements of Rayleigh light scattering by the polymer.

How do you calculate the average degree of polymerization?

Divide the molecular weight of the polymer by the molecular weight of the monomer unit to calculate the degree of polymerization. If the molecular mass of tetrafluoroethylene is 120,000, its degree of polymerization is 120,000 / 100 = 1,200.

What is the molecular weight of PVC?

The number-average molecular weight (M_n) of polyvinyl chloride (PVC) is 21, 150 g/mol.

What type of polymerization is involved in PVC?

PVC is produced by polymerization of vinyl chloride monomer (VCM). The main polymerization methods include suspension, emulsion, and bulk (mass) methods. About 80% of production involves suspension polymerization.

What is Z average molecular weight?

Finally, we can calculate the Z-average molecular weight by introducing yet another term for the weight of each player. This is done by multiplying the number of players of each weight by their weight three times. This average strongly emphasizes the largest members of the team to the exclusion of the smaller players.

What is degree of polymerization of cellulose?

The degree of polymerization of cellulose is calculated from the intrinsic viscosity of solutions prepared by dissolving cellulose in a suitable solvent, such as CED or cadoxen. The viscosity of pulp using the capillary viscometer method can be used for conventional pulps with up to 4% lignin.

Why is PVC toxic?

PVC contains dangerous chemical additives including phthalates, lead, cadmium, and/or organotins, which can be toxic to your child’s health. These toxic additives can leach out or evaporate into the air over time, posing unnecessary dangers to children.

What is the repeating unit of PVC?

The repeating unit or monomer of PVC is vinyl chloride.

Is PVC thermoplastic or thermosetting plastic?

Polyvinyl Chloride is a “thermoplastic” (as opposed to “thermoset”) material, which has to do with the way the plastic responds to heat.

What is the difference between molecular weight and formula weight?

The formula mass (formula weight) of a molecule is the sum of the atomic weights of the atoms in its empirical formula. The molecular mass (molecular weight) of a molecule is its average mass as calculated by adding together the atomic weights of the atoms in the molecular formula.

How is the weight-average degree of polymerization calculated?

The weight-average degree of polymerization is a weighted mean of the degrees of polymerization, weighted by the weight fractions (or the overall weight of the molecules) of the species.

When does rapid polymerization of PVC take place?

Rapid polymerization takes place at 62 – 75 °C to give 60µm aggregated spherical flocs composed of 0.1 µm primary particles, which form the basis for seeds in the final PVC grain. Conversion is taken to 7 – 12 % in about 30 min, by which time the initiator used is exhausted and the unreacted monomer is recycled.

How are the molecular weights of polymers different?

The molecular weights of polymers are much larger than the small molecules usually encountered in organic chemistry. Most chain reaction and step reaction polymerizations produce chains with many different lengths, so polymers also differ from small molecules in that the polymer molecular weights are average values.

How long does it take to convert prepolymeriser to PVC?

Conversion is taken to 7 – 12 % in about 30 min, by which time the initiator used is exhausted and the unreacted monomer is recycled. The slurry from the prepolymeriser is discharged in a 12 – 50 m3 autoclave, with fresh initiator and more VCM. In more recent plant designs the autoclave is replaced by a vertical reactor equipped with stirrers.